scientificamerican--2020-09-23--COVID-19 Testing Lab Shows How Colleges Can Reopen Safely

In a vast , unintentional public health experiment , millions of U.S. college students have descended on campuses to begin their fall semester with an unwelcome new arrival : the novel coronavirus .
Severe COVID-19 outbreaks have already forced some campuses to close and move instruction online .
Others have been fending off a surge in cases by relentlessly testing students and staff and isolating anyone whose results are positive .
In order to safely reopen , institutions of higher learning need the capacity to conduct a massive amount of coronavirus tests and get results back quickly .
The Broad @ @ @ @ @ @ @ and Harvard University offers a program that can help meet this need .
More than 100 colleges and universities in the U.S. Northeast have already contracted with the nonprofit biomedical research institution , whose expertise in high-volume genome sequencing allowed it to pivot to offering COVID-19 assays earlier this year .
The Broad Institute is capable of providing results within 24 hours at a price of $ 25 per test ( the prices of commercial laboratory assays vary but average around $ 130 ) .
As of mid-September , the institute had conducted @ @ @ @ @ @ @ million of them for colleges—with a positive rate of about 2 percent .
Representatives of several colleges and universities contracting with Broad told Scientific American they have so far been pleased with its testing efficiency , which—coupled with contact tracing and isolation of people who test positive—has helped keep case rates low .
Although these are still early days , this type of rapid testing could be a model for reopening colleges and other institutions nationwide .
In March the Broad Institute quickly retooled its state-of-the-art facility to process COVID-19 tests from nursing @ @ @ @ @ @ @ area .
It has also developed its own test , which has received emergency use authorization from the U.S. Food and Drug Administration .
In May several local colleges and universities reached out to the institute about the possibility of it providing large-scale testing .
Broad worked with them to figure out how such a program would work .
“ This wasn ’ t just , ‘ We 'll do a test , ’ ” says Stacey Gabriel , senior director of the institute ’ s genomics platform , who is overseeing the @ @ @ @ @ @ @ have to figure out how you ’ re going to basically onboard and teach these colleges how to order the test , how to do a nasal swab , how to label a tube .
We set up couriers [ to shuttle test collection kits between colleges and Broad ] .
There was a whole ecosystem that had to be created.
” Colleges working with Broad have been testing students when they arrive on campus .
And most of them will be tested twice a week throughout the semester .
Faculty and staff @ @ @ @ @ @ @ twice a week , depending on how often they are in contact with students .
Tufts University , which straddles Massachusetts ’ s cities of Medford and Somerville , is one of the 108 institutions currently contracting with Broad .
Tufts is a member of the Association of Independent Colleges and Universities in Massachusetts , which approached Broad about testing in May .
The university ’ s president Anthony Monaco is a geneticist himself : he used to run the Wellcome Trust Center for Human Genetics , a University of Oxford–based organization similar @ @ @ @ @ @ @ he was confident that Broad could handle the volume of college COVID-19 testing .
The institute had analyzed large quantities of genetic material for the Human Genome Project , so “ I just thought they were probably the best place in the world to do this , ” he says .
“ And it turned out to be true .
They ’ ve kept to the turnaround times , and they ’ ve been a joy to work with.
” Tufts , where classes began on September 8 , required students to quarantine @ @ @ @ @ @ @ they arrived on campus , and they could only leave to get a test , according to Monaco .
Students from outside the region of New York , New Jersey and New England ( as well as those from Rhode Island ) were required to have three negative assays before ending their quarantine .
Those who came from the region only needed one .
The test involves individuals swabbing each their own nostrils under a health care worker ’ s supervision and then sealing the swab in a tube , which is later @ @ @ @ @ @ @ .
Results are returned in an average of 24 hours .
If a student tests positive , that person is moved to an isolation unit and contact tracing begins .
As of September 19 , Tufts had had 29 positive cases out of a total of 47,100 tests—a rate of 0.6 percent .
Fewer than half of Tufts ’ s classes are being held in person , Monaco says .
The university has several operational status levels that it can adopt , according to the shifting COVID-19 situation , and Tufts is monitoring @ @ @ @ @ @ @ There are three [ scenarios ] that we really are going to be watching carefully , ” Monaco says .
One is a spike in the general infection rate at the campus itself .
“ We ’ ll be watching that very carefully and saying , ‘ Okay , at what point do we say that the rate is going up , and we ’ re not comfortable with it , and we want to change operations to try to reduce it ?
’ ” he says .
Another scenario is an outbreak @ @ @ @ @ @ @ an on-campus dorm or off-campus housing .
If contact tracing finds the transmission rate is above a certain level , that result would trigger another level of operation , Monaco says .
The third situation would be an outbreak in the wider community outside the campus .
“ The whole district might decide to curtail activities , or the state may decide , ” Monaco says .
“ Even if it ’ s not something we ’ re experiencing , we would react with the whole community to help.
” There is not @ @ @ @ @ @ @ would trigger a complete shutdown because that decision would have to incorporate factors such as the capacity of isolation units , he adds .
“ We ’ re not going straight from where we are now to sending everyone home , ” Monaco says .
Bowdoin College in Brunswick , Me.
, is also contracting with the Broad Institute .
“ If we were going to reopen and bring any students back , we needed to make sure that we would have three pieces , ” says Mike Ranen , Bowdoin ’ s @ @ @ @ @ @ @ of residential and student life , who works as its COVID-19 resource coordinator .
“ We would need community standards around social distancing , facial coverings and hygiene .
We would need a robust contact-tracing program and be able to isolate positive students , as well as students who are in close contact and need to go into quarantine .
And [ we require ] a robust testing protocol so we can quickly isolate students , ideally before they are able to spread [ the disease ] to other people .
Students returned @ @ @ @ @ @ @ as August 29 , and only about 40 percent of the college ’ s total student body is on campus , Ranen says .
During the first two weeks of class , students were tested three times per week .
And they will be tested twice a week as the term progresses .
Faculty and staff who have frequent contact with students take assays twice a week , and others do so once a week .
Most of the college ’ s classes are remote , and students can attend them from a @ @ @ @ @ @ @ tents set up around the campus .
As of September 18 , Bowdoin has had three positive cases ( one of whom tested positive before arriving on campus ) among 5,982 student tests and no positives out of 5,270 employee tests .
Like Tufts , Bowdoin has a system of status levels based on the number of COVID-19 cases , usage of its isolation and quarantine facilities , and transmission in the surrounding area .
“ We don ’ t have an exact number for when we would either place a campus in @ @ @ @ @ @ @ the campus .
There ’ s going to be more of a holistic approach , ” Ranen says .
One consideration in shutting down the campus is whether it is safe to send students home .
“ We do n't want people ... bringing the virus to their hometowns and their home communities , ” he says .
It is not only private colleges that have partnered with the Broad Institute : the University of Massachusetts Amherst , a public research institution , also contracted with the nonprofit to provide testing .
“ @ @ @ @ @ @ @ fit , based on the turnaround time and based on the cost , which is obviously a big thing as well .
The Broad Institute just became a really great partner for us , ” says Jeffrey Hescock , UMass Amherst ’ s executive director of environmental health and safety and emergency management .
The university has converted its basketball arena into a Public Health Promotion Center where , which Hescock co-directs .
There students and staff come to get tested either once or twice a week , depending on whether they live @ @ @ @ @ @ @ their own nasal swabs under supervision—often by students from the university ’ s College of Nursing and its School of Public Health and Health Sciences , Hescock says .
As of September 17 , the university had had 17 positive cases out of 41,716 tests .
“ We have a team every day made up of [ epidemiologists ] that meets at 10 in the morning to discuss the day before ’ s activities , ” Hescock says .
If someone tests negative , that person gets an e-mail .
If someone test @ @ @ @ @ @ @ to that individual and obtain a list of his or her close contacts .
The nurse will then either follow up on those contacts or pass them off to a student contact tracer .
“ We 've been extremely pleased with working with [ the Broad Institute ] and the turnaround time of the test results , ” Hescock says .
Not all colleges and universities have been able to offer this kind of frequent testing , however .
And even with testing , COVID-19 outbreaks have already erupted at many institutions across @ @ @ @ @ @ @ parts of the country , the Northeast has benefitted from a lower rate of community transmission in recent months .
But Gabriel says Broad ’ s testing program would not be hard to replicate elsewhere .
“ I do n't think it ’ s unrealistic at all , ” she says , adding that some colleges and universities ( such as Boston University and the University of New Hampshire ) have been conducting their own testing .
“ Honestly , it ’ s just deciding to do it , which I think is @ @ @ @ @ @ @ the coronavirus outbreak from Scientific American here .
And read coverage from our international network of magazines here .

In a vast, unintentional public health experiment, millions of U.S. college students have descended on campuses to begin their fall semester with an unwelcome new arrival: the novel coronavirus. Severe COVID-19 outbreaks have already forced some campuses to close and move instruction online. Others have been fending off a surge in cases by relentlessly testing students and staff and isolating anyone whose results are positive.
In order to safely reopen, institutions of higher learning need the capacity to conduct a massive amount of coronavirus tests and get results back quickly. The Broad Institute of the Massachusetts Institute of Technology and Harvard University offers a program that can help meet this need. More than 100 colleges and universities in the U.S. Northeast have already contracted with the nonprofit biomedical research institution, whose expertise in high-volume genome sequencing allowed it to pivot to offering COVID-19 assays earlier this year. The Broad Institute is capable of providing results within 24 hours at a price of $25 per test (the prices of commercial laboratory assays vary but average around $130). As of mid-September, the institute had conducted more than two million tests—at least one million of them for colleges—with a positive rate of about 2 percent.
Representatives of several colleges and universities contracting with Broad told Scientific American they have so far been pleased with its testing efficiency, which—coupled with contact tracing and isolation of people who test positive—has helped keep case rates low. Although these are still early days, this type of rapid testing could be a model for reopening colleges and other institutions nationwide.
In March the Broad Institute quickly retooled its state-of-the-art facility to process COVID-19 tests from nursing homes and other institutions in the Massachusetts area. It has also developed its own test, which has received emergency use authorization from the U.S. Food and Drug Administration. In May several local colleges and universities reached out to the institute about the possibility of it providing large-scale testing. Broad worked with them to figure out how such a program would work. “This wasn’t just, ‘We'll do a test,’” says Stacey Gabriel, senior director of the institute’s genomics platform, who is overseeing the COVID-19 testing program. “You also have to figure out how you’re going to basically onboard and teach these colleges how to order the test, how to do a nasal swab, how to label a tube. We set up couriers [to shuttle test collection kits between colleges and Broad]. There was a whole ecosystem that had to be created.”
Colleges working with Broad have been testing students when they arrive on campus. And most of them will be tested twice a week throughout the semester. Faculty and staff will also be tested either once or twice a week, depending on how often they are in contact with students.
Tufts University, which straddles Massachusetts’s cities of Medford and Somerville, is one of the 108 institutions currently contracting with Broad. Tufts is a member of the Association of Independent Colleges and Universities in Massachusetts, which approached Broad about testing in May. The university’s president Anthony Monaco is a geneticist himself: he used to run the Wellcome Trust Center for Human Genetics, a University of Oxford–based organization similar to the Broad Institute, and says he was confident that Broad could handle the volume of college COVID-19 testing. The institute had analyzed large quantities of genetic material for the Human Genome Project, so “I just thought they were probably the best place in the world to do this,” he says. “And it turned out to be true. They’ve kept to the turnaround times, and they’ve been a joy to work with.”
Tufts, where classes began on September 8, required students to quarantine in their dorm rooms as soon as they arrived on campus, and they could only leave to get a test, according to Monaco. Students from outside the region of New York, New Jersey and New England (as well as those from Rhode Island) were required to have three negative assays before ending their quarantine. Those who came from the region only needed one. The test involves individuals swabbing each their own nostrils under a health care worker’s supervision and then sealing the swab in a tube, which is later collected and sent to Broad for analysis. Results are returned in an average of 24 hours. If a student tests positive, that person is moved to an isolation unit and contact tracing begins. As of September 19, Tufts had had 29 positive cases out of a total of 47,100 tests—a rate of 0.06 percent.*
Fewer than half of Tufts’s classes are being held in person, Monaco says. The university has several operational status levels that it can adopt, according to the shifting COVID-19 situation, and Tufts is monitoring early indicators of potential outbreaks. “There are three [scenarios] that we really are going to be watching carefully,” Monaco says. One is a spike in the general infection rate at the campus itself. “We’ll be watching that very carefully and saying, ‘Okay, at what point do we say that the rate is going up, and we’re not comfortable with it, and we want to change operations to try to reduce it?’” he says. Another scenario is an outbreak of infections at, for example, an on-campus dorm or off-campus housing. If contact tracing finds the transmission rate is above a certain level, that result would trigger another level of operation, Monaco says. The third situation would be an outbreak in the wider community outside the campus. “The whole district might decide to curtail activities, or the state may decide,” Monaco says. “Even if it’s not something we’re experiencing, we would react with the whole community to help.” There is not an exact threshold of case numbers that would trigger a complete shutdown because that decision would have to incorporate factors such as the capacity of isolation units, he adds. “We’re not going straight from where we are now to sending everyone home,” Monaco says.
Bowdoin College in Brunswick, Me., is also contracting with the Broad Institute. “If we were going to reopen and bring any students back, we needed to make sure that we would have three pieces,” says Mike Ranen, Bowdoin’s associate dean of student affairs and director of residential and student life, who works as its COVID-19 resource coordinator. “We would need community standards around social distancing, facial coverings and hygiene. We would need a robust contact-tracing program and be able to isolate positive students, as well as students who are in close contact and need to go into quarantine. And [we require] a robust testing protocol so we can quickly isolate students, ideally before they are able to spread [the disease] to other people.
Students returned to Bowdoin to resume classes as early as August 29, and only about 40 percent of the college’s total student body is on campus, Ranen says. During the first two weeks of class, students were tested three times per week. And they will be tested twice a week as the term progresses. Faculty and staff who have frequent contact with students take assays twice a week, and others do so once a week. Most of the college’s classes are remote, and students can attend them from a dorm room or one of several outdoor tents set up around the campus. As of September 18, Bowdoin has had three positive cases (one of whom tested positive before arriving on campus) among 5,982 student tests and no positives out of 5,270 employee tests.
Like Tufts, Bowdoin has a system of status levels based on the number of COVID-19 cases, usage of its isolation and quarantine facilities, and transmission in the surrounding area. “We don’t have an exact number for when we would either place a campus in more of a strict lockdown or close the campus. There’s going to be more of a holistic approach,” Ranen says. One consideration in shutting down the campus is whether it is safe to send students home. “We don't want people ... bringing the virus to their hometowns and their home communities,” he says.
It is not only private colleges that have partnered with the Broad Institute: the University of Massachusetts Amherst, a public research institution, also contracted with the nonprofit to provide testing. “We just thought it was a great fit, based on the turnaround time and based on the cost, which is obviously a big thing as well. The Broad Institute just became a really great partner for us,” says Jeffrey Hescock, UMass Amherst’s executive director of environmental health and safety and emergency management.
The university has converted its basketball arena into a Public Health Promotion Center where, which Hescock co-directs. There, students and staff come to get tested either once or twice a week, depending on whether they live or work on campus. Individuals collect their own nasal swabs under supervision—often by students from the university’s College of Nursing and its School of Public Health and Health Sciences, Hescock says. As of September 17, the university had had 17 positive cases out of 41,716 tests. “We have a team every day made up of [epidemiologists] that meets at 10 in the morning to discuss the day before’s activities,” Hescock says. If someone tests negative, that person gets an e-mail. If someone test positive, a nurse will reach out to that individual and obtain a list of his or her close contacts. The nurse will then either follow up on those contacts or pass them off to a student contact tracer. “We've been extremely pleased with working with [the Broad Institute] and the turnaround time of the test results,” Hescock says.
Not all colleges and universities have been able to offer this kind of frequent testing, however. And even with testing, COVID-19 outbreaks have already erupted at many institutions across the U.S. Compared with most other parts of the country, the Northeast has benefitted from a lower rate of community transmission in recent months. But Gabriel says Broad’s testing program would not be hard to replicate elsewhere. “I don't think it’s unrealistic at all,” she says, adding that some colleges and universities (such as Boston University and the University of New Hampshire) have been conducting their own testing. “Honestly, it’s just deciding to do it, which I think is half the battle.”
Read more about the coronavirus outbreak from Scientific American here. And read coverage from our international network of magazines here.
*Editor’s Note (9/23/20): This sentence has been edited after posting to correct an error in the positive coronavirus test rate for Tufts University.


scientificamerican--2020-09-23--The First-Ever Image of a Black Hole Is Now a Movie

The historic first image of a black hole unveiled last year has now been turned into a movie .
The short sequence of frames shows how the appearance of the black hole ’ s surroundings changes over years as its gravity stirs the material around it into a constant maelstrom .
The images show a lopsided blob of light swirling around the supermassive black hole at the centre of the galaxy M87 .
To create them , the Event Horizon Telescope ( EHT ) collaboration — which harnesses a planet-wide network of observatories — exhumed old data on the black @ @ @ @ @ @ @ model based on the image released in April 2019 , to show how the surroundings have evolved over eight years .
Although it relies partly on guesswork , the result gives astronomers rich insights into the behaviour of black holes , the intense gravity of which sucks in matter and light around them .
“ Because the flow of matter falling onto a black hole is turbulent , we can see that the ring wobbles with time , ” says lead author Maciek Wielgus , a radio astronomer at Harvard University in Cambridge @ @ @ @ @ @ @ appeared on 23 September in The Astrophysical Journal , offers a taste of what the team might be able to do in the near future , as its techniques improve .
“ In a few years , it could really start to look like a movie , ” Wielgus says .
The black-hole image that the EHT collaboration unveiled last year made the front pages of newspapers around the world .
It portrayed M87* , the supermassive black hole at the centre of the M87 galaxy , some 17 megaparsecs ( 55 million @ @ @ @ @ @ @ constructed the picture by combining radio-frequency signals they had collected from observatories across Earth over two nights in April 2017 .
Their feat has been compared to resolving the shape of a doughnut on the surface of the Moon from Earth .
Although blurry , the image matched the predictions of Albert Einstein ’ s general theory of relativity for what the immediate neighbourhood of a black hole should look like .
In particular , it gave researchers the first direct evidence of the shadow of an event horizon , the surface of @ @ @ @ @ @ @ black hole from its surroundings .
This darker disk was set against a ring of light emitted by superheated matter just outside the event horizon .
Strikingly , one side of the ring appeared brighter .
This was expected , owing to a combination of effects in the complex dynamics around a black hole .
In particular , matter falling into the void should spiral at a high velocity outside the black hole ’ s equator , forming what astrophysicists call the accretion disk .
The lopsided look is in part to do @ @ @ @ @ @ @ side of the disk that rotates towards the observer , the motion of the matter boosts the radiation , making it look brighter ; the opposite happens on receding side .
On the basis of those results , Wielgus wanted to go back and look at the older data from EHT telescopes to see whether he could reinterpret them , using the 2017 picture as a guide .
The EHT had been observing M87* since 2009 , initially using telescopes at just three locations .
As the team added more observatories to the @ @ @ @ @ @ @ observations improved .
In 2017 , the collaboration involved eight observatories that spanned the globe from Hawaii and Chile to Europe , reaching for the first time the level at which the EHT could produce an actual image .
The older data consisted of four batches , collected in 2009 , 2011 , 2012 and 2013 , two of which had remained unpublished .
“ To a degree , they were forgotten , because everyone was super excited about the 2017 data , ” Wielgus says .
With a group of other EHT @ @ @ @ @ @ @ found them to be consistent with the results of the 2017 campaign , including the presence of a dark disk and a bright ring .
And although , by themselves , the 2009–13 data batches did not have sufficient resolution to produce pictures , the team was able to generate synthetic images for each of the years by combining the limited data available with a mathematical model of the black hole built from the 2017 data .
And the results turned out to contain more information than Wielgus expected .
Like the 2017 @ @ @ @ @ @ @ of the ring was brighter than the other — but the bright spot moved around .
This could be because different regions of the accretion disk became brighter or dimmer , which could enhance or sometimes even cancel out the Doppler brightening .
This was not unexpected , the authors say : although the M87* black hole itself does not change from year to year , the environment around it does .
On a scale of several weeks , strong magnetic fields should stir the accretion disk and produce hotter spots that then @ @ @ @ @ @ @ , a separate team reported evidence of a blob of hot gas circling Sagittarius A* , the Milky Way ’ s central black hole , over the course of around 1 hour .
Because M87* , at 6.5 billion times the mass of the Sun , is more than 1,000 times the size of Sagittarius A* , the dynamics around M87* take longer to unfold .
The EHT collaboration attempts to observe M87* and Sagittarius A* every year , in late March or early April .
That is when weather conditions are most @ @ @ @ @ @ @ many sites in its network .
The 2020 campaign had to be scrapped because of restrictions owing to the COVID–19 pandemic , but the team hopes to have another chance in 2021 .
If all goes well , more observatories — including one in Greenland and one in France — will join the effort .
The team also hopes that next year ’ s campaign will include its first global observations using shorter-wavelength radiation .
Although more challenging to see through Earth ’ s atmosphere , this would improve the resolution of the @ @ @ @ @ @ @ even closer to that black-hole shadow , and get sharper images , ” says EHT member Sara Issaoun , a radio astronomer at Radboud University in Nijmegen , the Netherlands .
This article is reproduced with permission and was first published on September 23 2020 .

The historic first image of a black hole unveiled last year has now been turned into a movie. The short sequence of frames shows how the appearance of the black hole’s surroundings changes over years as its gravity stirs the material around it into a constant maelstrom.
The images show a lopsided blob of light swirling around the supermassive black hole at the centre of the galaxy M87. To create them, the Event Horizon Telescope (EHT) collaboration — which harnesses a planet-wide network of observatories — exhumed old data on the black hole and combined these with a mathematical model based on the image released in April 2019, to show how the surroundings have evolved over eight years. Although it relies partly on guesswork, the result gives astronomers rich insights into the behaviour of black holes, the intense gravity of which sucks in matter and light around them.
“Because the flow of matter falling onto a black hole is turbulent, we can see that the ring wobbles with time,” says lead author Maciek Wielgus, a radio astronomer at Harvard University in Cambridge, Massachusetts.
The work, which appeared on 23 September in The Astrophysical Journal, offers a taste of what the team might be able to do in the near future, as its techniques improve. “In a few years, it could really start to look like a movie,” Wielgus says.
Wobbling ring
The black-hole image that the EHT collaboration unveiled last year made the front pages of newspapers around the world. It portrayed M87*, the supermassive black hole at the centre of the M87 galaxy, some 17 megaparsecs (55 million light years) away. The researchers constructed the picture by combining radio-frequency signals they had collected from observatories across Earth over two nights in April 2017. Their feat has been compared to resolving the shape of a doughnut on the surface of the Moon from Earth.
A series of images constructed from observational data and mathematical modelling show the evolution of the black hole at the center of the M87 galaxy from 2009 to 2017. Credit: M. Wielgus, D. Pesce & the EHT Collaboration
Although blurry, the image matched the predictions of Albert Einstein’s general theory of relativity for what the immediate neighbourhood of a black hole should look like. In particular, it gave researchers the first direct evidence of the shadow of an event horizon, the surface of ‘no return’ that separates a black hole from its surroundings. This darker disk was set against a ring of light emitted by superheated matter just outside the event horizon.
Strikingly, one side of the ring appeared brighter. This was expected, owing to a combination of effects in the complex dynamics around a black hole. In particular, matter falling into the void should spiral at a high velocity outside the black hole’s equator, forming what astrophysicists call the accretion disk. The lopsided look is in part to do with the Doppler effect: on the side of the disk that rotates towards the observer, the motion of the matter boosts the radiation, making it look brighter; the opposite happens on receding side.
Revisiting data
On the basis of those results, Wielgus wanted to go back and look at the older data from EHT telescopes to see whether he could reinterpret them, using the 2017 picture as a guide. The EHT had been observing M87* since 2009, initially using telescopes at just three locations. As the team added more observatories to the EHT network, the quality of the observations improved. In 2017, the collaboration involved eight observatories that spanned the globe from Hawaii and Chile to Europe, reaching for the first time the level at which the EHT could produce an actual image.
The older data consisted of four batches, collected in 2009, 2011, 2012 and 2013, two of which had remained unpublished. “To a degree, they were forgotten, because everyone was super excited about the 2017 data,” Wielgus says. With a group of other EHT researchers, he reanalysed the data and found them to be consistent with the results of the 2017 campaign, including the presence of a dark disk and a bright ring. And although, by themselves, the 2009–13 data batches did not have sufficient resolution to produce pictures, the team was able to generate synthetic images for each of the years by combining the limited data available with a mathematical model of the black hole built from the 2017 data.
And the results turned out to contain more information than Wielgus expected. Like the 2017 picture, they revealed that one side of the ring was brighter than the other — but the bright spot moved around. This could be because different regions of the accretion disk became brighter or dimmer, which could enhance or sometimes even cancel out the Doppler brightening.
Dynamic disk
This was not unexpected, the authors say: although the M87* black hole itself does not change from year to year, the environment around it does. On a scale of several weeks, strong magnetic fields should stir the accretion disk and produce hotter spots that then orbit the black hole. In 2018, a separate team reported evidence of a blob of hot gas circling Sagittarius A*, the Milky Way’s central black hole, over the course of around 1 hour. Because M87*, at 6.5 billion times the mass of the Sun, is more than 1,000 times the size of Sagittarius A*, the dynamics around M87* take longer to unfold.
The EHT collaboration attempts to observe M87* and Sagittarius A* every year, in late March or early April. That is when weather conditions are most likely to be good simultaneously at the many sites in its network. The 2020 campaign had to be scrapped because of restrictions owing to the COVID–19 pandemic, but the team hopes to have another chance in 2021. If all goes well, more observatories — including one in Greenland and one in France — will join the effort.
The team also hopes that next year’s campaign will include its first global observations using shorter-wavelength radiation. Although more challenging to see through Earth’s atmosphere, this would improve the resolution of the EHT images. “We would get even closer to that black-hole shadow, and get sharper images,” says EHT member Sara Issaoun, a radio astronomer at Radboud University in Nijmegen, the Netherlands.
This article is reproduced with permission and was first published on September 23 2020.


scientificamerican--2020-09-23--Watch a Robot AI Beat World-Class Curling Competitors

Artificial intelligence still needs to bridge the “ sim-to-real ” gap .
Deep-learning techniques that are all the rage in @ @ @ @ @ mastering cerebral games , including chess and Go , both of which can be played @ @ @ @ @ translating simulations to the physical world remains a bigger challenge .
A robot named Curly @ @ @ @ @ learning ” —making improvements as it corrects its own errors—came out on top in three @ @ @ @ @ human opponents from South Korean teams that included a women ’ s team and a @ @ @ @ @ wheelchair team .
( No brooms were used ) .
One crucial finding was that @ @ @ @ @ ability to adapt to changing ice conditions .
“ These results indicate that the gap @ @ @ @ @ real world can be narrowed , ” the joint South Korean-German research team wrote in @ @ @ @ @ .

Artificial intelligence still needs to bridge the “sim-to-real” gap. Deep-learning techniques that are all the rage in AI log superlative performances in mastering cerebral games, including chess and Go, both of which can be played on a computer. But translating simulations to the physical world remains a bigger challenge.
A robot named Curly that uses “deep reinforcement learning”—making improvements as it corrects its own errors—came out on top in three of four games against top-ranked human opponents from South Korean teams that included a women’s team and a reserve squad for the national wheelchair team. (No brooms were used).
One crucial finding was that the AI system demonstrated its ability to adapt to changing ice conditions. “These results indicate that the gap between physics-based simulators and the real world can be narrowed,” the joint South Korean-German research team wrote in Science Robotics on September 23.


scientificamerican--2020-09-23--Is There Life on Venus? These Missions Could Find It

For decades , scientists have treated Venus as Earth ’ s estranged sister gone bad .
Once considered a promising planetary destination because of its near equivalence to our own world in size and mass , robotic scouts revealed Venus to be a pressure-cooked globe inimical to life—and to any further efforts to explore it .
Now , however , hints of a possible Venusian biosphere are strengthening a surge of interest in our sister world .
On September 14 an international team of researchers , led by Jane Greaves of Cardiff University in Wales , announced the detection of @ @ @ @ @ @ @ planet ’ s atmosphere where temperatures and pressures are relatively balmy .
Here on Earth , phosphine is only made industrially or by microbes that flourish in oxygen-free environments—meaning it could be a potential “ biosignature ” indicative of life .
If confirmed , the finding would point to either of two possibilities : bizarre and wholly unexpected geochemistry on a lifeless Venus or the presence of some form of aerial alien biology in the planet ’ s clement cloud decks .
The bombshell announcement elicited excitement around the world , including from @ @ @ @ @ @ @ , he called the discovery “ the most significant development yet in building the case for life off Earth ” and concluded with a recommendation to “ prioritize Venus ” in planning for future interplanetary missions .
The lively news from Venus—and Bridenstine ’ s apparent endorsement of further exploration there—comes at an auspicious time .
Under its Discovery Program , for instance , NASA is considering four space missions for launch later this decade , and two of them would be orbiters meant to scrutinize the cloud-shrouded rocky world .
The DAVINCI+ @ @ @ @ @ @ @ Gases , Chemistry , and Imaging Plus ) mission consists of an orbiter that would , as part of its investigations , dispatch an instrumented probe to the Venusian atmosphere .
Its competitor , the “ truth-seeking ” VERITAS ( Venus Emissivity , Radio Science , InSAR , Topography , and Spectroscopy ) orbiter , does not presently include an atmospheric probe .
Instead the spacecraft would focus on radar scanning to help ascertain the planet ’ s geologic history .
NASA ’ s announcement of its choice among these competing missions and @ @ @ @ @ @ @ .
Beyond the current Discovery-class candidates , a newly completed Venus Flagship Mission study lays out a much more ambitious all-in-one venture that would send an orbiter , lander , two small satellites and a variable-altitude aerobot to scout our sister world .
Such a mission , its proponents say , could set sail in June 2031 , place its five science platforms at Venus in 2034 and culminate in a landing on the surface in May 2035 .
NASA is not the only space agency with Venus in its sights .
The @ @ @ @ @ @ @ considering a planet-scanning radar probe of its own , dubbed EnVision , that could launch in 2032 .
In addition , Russia ’ s proposed Venera-D mission could perhaps lift off as early as 2025 .
The mission was initially billed as a projected joint venture with the U.S. Roscosmos , Russia ’ s space agency , now says that while it is not refusing to work with that country , it is avoiding “ wide international cooperation.
” This assertion reflects that Russia , more than any other spacefaring nation , has @ @ @ @ @ @ @ to preserve its preeminence there .
“ We think that Venus is a Russian planet , so we shouldn ’ t lag behind , ” Roscosmos chief Dmitry Rogozin recently said .
Consequently , a comprehensive Russian-charted Venus research program consisting of several missions is reportedly in the works .
Marking the calendar for nascent , yet to be funded space-agency missions to unravel Venus ’ s lingering mysteries is , thankfully , not the only option available .
There are other opportunities to grab up-close observations of the planet in the offing—including @ @ @ @ @ @ @ October 2018 , ESA ’ s BepiColombo spacecraft is headed for the planet Mercury .
But to reach its target , the craft ’ s trajectory includes two speed-boosting flybys of Venus , first in mid-October and then in August 2021 .
Some of BepiColombo ’ s instruments that were designed to study Mercury can also be utilized to reconnoiter Venus ’ s atmosphere , the mission ’ s scientists say .
“ While the first flyby is already planned , there is a possibility of configuring the second flyby to look for @ @ @ @ @ @ @ Mount Holyoke College , who chairs NASA ’ s Venus Exploration Analysis Group .
Even so , Dyar adds that to place the phosphine discovery in a planetary context , she and other researchers must know more about Venus ’ s present-day habitability via measurements of atmospheric water vapor and “ hydrated ” minerals on the surface .
“ Because water is the key to habitability , at least for life as we know it , following the water is what is really important here , ” she says .
The reality is @ @ @ @ @ @ @ remain unsolved until several critical pieces of information are in hand , says Kandi Jessup , a senior research scientist at the Southwest Research Institute ( SwRI ) .
“ Definitive statements about biosignatures in Venus ’ s atmosphere are dependent on how well we understand the chemistry occurring within the clouds , the rate of active volcanism at Venus , and any links that may exist between Venus ’ s active volcanism and current cloud chemistry , ” she says .
All of the proposals for new Venus missions are designed to @ @ @ @ @ @ @ understanding of the planet ’ s environment .
But none are likely to individually answer the critical question of whether our sister world actually harbors life .
If subsequent scouting of Venus ’ s atmosphere reveals further indications of biosignatures and habitability , there is one possibility that could single-handedly deliver definitive proof of life : a sample return mission to gather potential organic material from plausibly habitable Venusian cloud layers and ferry it back to Earth .
With a few caveats , that is the view of astrobiologist Dirk Schulze-Makuch , an @ @ @ @ @ @ @ Schulze-Makuch says that for microbes to flourish in Venus ’ s clouds , where sulfuric acid is abundant and water is scarce , they would have to be adapted to endure conditions beyond those encountered by Earth ’ s microorganisms .
“ But that doesn ’ t mean they couldn ’ t exist , ” he adds .
Indeed , Schulze-Makuch maintains , finding further evidence of life on Venus could free astrobiologists from the “ arrogance ” of assuming that adaptations to extreme conditions exhibited by Earth life will always be the @ @ @ @ @ @ @ there are only a few localities with hyperacidity and none as extreme as on Venus , so there would not be much motivation for Earth life to evolve such adaptations , ” Schulze-Makuch says .
“ On Venus , however , life might have had up to one billion years ’ time to evolve such adaptations ” as a runaway greenhouse effect gradually pushed the once temperate world into its present hellish state .
In the meantime spotting a potential biosignature on Venus is spurring a private-sector response .
For example , Breakthrough @ @ @ @ @ @ @ effort , is sponsoring a study by top-tier specialists that will seek to clarify the parameters of primitive life dwelling within Venus ’ s hostile skies .
The group is led by Sara Seager , an astrophysicist at the Massachusetts Institute of Technology and a collaborator on the phosphine-discovery studies .
Its charge is “ to push the envelope to try to understand what kind of life could exist in the very harsh Venus atmosphere and what further evidence for life a mission to Venus could search for , ” she says .
@ @ @ @ @ @ @ private American aerospace manufacturer and launch service for small satellites that is slated to conduct its first deep-space mission next year : sending a NASA payload to the moon .
That lunar foray will only be a prelude to an even more ambitious endeavor : a pint-sized Venusian atmospheric probe to seek additional evidence for or against potential life there .
Riding on one of the company ’ s Electron rockets onboard its small , proprietary Photon spacecraft , the mission could lift off as early as 2023 .
“ I 'm completely @ @ @ @ @ @ @ Lab ’ s founder and chief executive Peter Beck .
“ There is so much we can learn about a planet that is so analogous to Earth .
We understand life as it exists here on Earth , but life on Venus could be something really at odds with everything we know .
If we can prove life exists off Earth , then it ’ s fair to assume it could be prolific throughout the universe.
” Moreover , beyond the search for life , Beck says , Venus could offer another message @ @ @ @ @ @ @ amount we can unpack about climate change from studying Venus , ” he says .
“ Venus was once possibly not to dissimilar to Earth , with oceans and water .
Then it was enveloped in a shroud of carbon dioxide that drove a runaway greenhouse effect , pushing temperatures to extremes and turning the planet into the hellscape it is today .
By taking a closer look at Venus , we might just be able to provide a glimpse into what could lay ahead for Earth in the case of runaway climate @ @ @ @ @ @ @ and See The purported phosphine detection is indeed interesting , says Chris McKay , an astrobiologist at NASA ’ s Ames Research Center .
But he questions whether phosphine could actually be considered a biosignature .
The claims of phosphine on Venus hinge on the interpretation of a single feature , a dip in a spectrum of the planet ’ s atmosphere that was attributed to the gas ’ s presence .
Researchers saw the phosphine line in spectra gathered by two independent facilities : the James Clerk Maxwell Telescope on Mauna Kea @ @ @ @ @ @ @ Array observatory in Chile .
That dual detection is a boon for arguments that the finding is genuine , McKay says , but “ a robust detection would have several spectral features that are in relative agreement ” rather than just one .
Advocates of airborne biology on Venus make a good case that there are no natural sources of phosphine on the planet , McKay adds .
Then again , an equally compelling case can be made that because they are impoverished of water and enriched in sulfuric acid , the the @ @ @ @ @ @ @ fact , not at all suitable for life .
“ So it would be premature to jump to any conclusion , ” he says .
“ Basically , we have no coherent theory for how phosphine could be present on Venus ... .
Don ’ t bet the farm on life just yet .
It may not be phosphine .
And if it is , it may not be biotic.
” Like McKay , another expert firmly in the “ wait and see ” contingent is Robert Grimm , a program director in @ @ @ @ @ @ @ out a checklist of what researchers should do next : “ Work out how good the observation is .
Vet their claim that there can be no abiotic mechanisms .
Look at the NASA queue and see what fits , ” Grimm says .
“ If they exist , the bugs have been there for at least hundreds of millions of years .
They can wait another decade .
”

For decades, scientists have treated Venus as Earth’s estranged sister gone bad. Once considered a promising planetary destination because of its near equivalence to our own world in size and mass, robotic scouts revealed Venus to be a pressure-cooked globe inimical to life—and to any further efforts to explore it. Now, however, hints of a possible Venusian biosphere are strengthening a surge of interest in our sister world.
On September 14 an international team of researchers, led by Jane Greaves of Cardiff University in Wales, announced the detection of phosphine gas lingering in layers of the planet’s atmosphere where temperatures and pressures are relatively balmy. Here on Earth, phosphine is only made industrially or by microbes that flourish in oxygen-free environments—meaning it could be a potential “biosignature” indicative of life. If confirmed, the finding would point to either of two possibilities: bizarre and wholly unexpected geochemistry on a lifeless Venus or the presence of some form of aerial alien biology in the planet’s clement cloud decks.
The bombshell announcement elicited excitement around the world, including from NASA administrator Jim Bridenstine. On Twitter, he called the discovery “the most significant development yet in building the case for life off Earth” and concluded with a recommendation to “prioritize Venus” in planning for future interplanetary missions.
Proposed Probes
The lively news from Venus—and Bridenstine’s apparent endorsement of further exploration there—comes at an auspicious time. Under its Discovery Program, for instance, NASA is considering four space missions for launch later this decade, and two of them would be orbiters meant to scrutinize the cloud-shrouded rocky world.
The DAVINCI+ (Deep Atmosphere Venus Investigation of Noble Gases, Chemistry, and Imaging Plus) mission consists of an orbiter that would, as part of its investigations, dispatch an instrumented probe to the Venusian atmosphere. Its competitor, the “truth-seeking” VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy) orbiter, does not presently include an atmospheric probe. Instead the spacecraft would focus on radar scanning to help ascertain the planet’s geologic history. NASA’s announcement of its choice among these competing missions and two others is expected sometime next year.
Beyond the current Discovery-class candidates, a newly completed Venus Flagship Mission study lays out a much more ambitious all-in-one venture that would send an orbiter, lander, two small satellites and a variable-altitude aerobot to scout our sister world. Such a mission, its proponents say, could set sail in June 2031, place its five science platforms at Venus in 2034 and culminate in a landing on the surface in May 2035.
NASA is not the only space agency with Venus in its sights. The European Space Agency (ESA) is considering a planet-scanning radar probe of its own, dubbed EnVision, that could launch in 2032. In addition, Russia’s proposed Venera-D mission could perhaps lift off as early as 2025. The mission was initially billed as a projected joint venture with the U.S. Roscosmos, Russia’s space agency, now says that while it is not refusing to work with that country, it is avoiding “wide international cooperation.” This assertion reflects that Russia, more than any other spacefaring nation, has historically dominated the exploration of Venus—and seeks to preserve its preeminence there.
“We think that Venus is a Russian planet, so we shouldn’t lag behind,” Roscosmos chief Dmitry Rogozin recently said. Consequently, a comprehensive Russian-charted Venus research program consisting of several missions is reportedly in the works.
BepiColombo’s Sneak Peek
Marking the calendar for nascent, yet to be funded space-agency missions to unravel Venus’s lingering mysteries is, thankfully, not the only option available. There are other opportunities to grab up-close observations of the planet in the offing—including one coming next month.
Launched in October 2018, ESA’s BepiColombo spacecraft is headed for the planet Mercury. But to reach its target, the craft’s trajectory includes two speed-boosting flybys of Venus, first in mid-October and then in August 2021. Some of BepiColombo’s instruments that were designed to study Mercury can also be utilized to reconnoiter Venus’s atmosphere, the mission’s scientists say.
“While the first flyby is already planned, there is a possibility of configuring the second flyby to look for phosphine,” says Darby Dyar of Mount Holyoke College, who chairs NASA’s Venus Exploration Analysis Group.
Even so, Dyar adds that to place the phosphine discovery in a planetary context, she and other researchers must know more about Venus’s present-day habitability via measurements of atmospheric water vapor and “hydrated” minerals on the surface. “Because water is the key to habitability, at least for life as we know it, following the water is what is really important here,” she says.
The reality is that the puzzle of Venusian phosphine will remain unsolved until several critical pieces of information are in hand, says Kandi Jessup, a senior research scientist at the Southwest Research Institute (SwRI). “Definitive statements about biosignatures in Venus’s atmosphere are dependent on how well we understand the chemistry occurring within the clouds, the rate of active volcanism at Venus, and any links that may exist between Venus’s active volcanism and current cloud chemistry,” she says. All of the proposals for new Venus missions are designed to advance some aspect of our necessarily broad understanding of the planet’s environment. But none are likely to individually answer the critical question of whether our sister world actually harbors life.
Bringing Venus Down to Earth
If subsequent scouting of Venus’s atmosphere reveals further indications of biosignatures and habitability, there is one possibility that could single-handedly deliver definitive proof of life: a sample return mission to gather potential organic material from plausibly habitable Venusian cloud layers and ferry it back to Earth. With a few caveats, that is the view of astrobiologist Dirk Schulze-Makuch, an adjunct professor at Washington State University.
Schulze-Makuch says that for microbes to flourish in Venus’s clouds, where sulfuric acid is abundant and water is scarce, they would have to be adapted to endure conditions beyond those encountered by Earth’s microorganisms. “But that doesn’t mean they couldn’t exist,” he adds. Indeed, Schulze-Makuch maintains, finding further evidence of life on Venus could free astrobiologists from the “arrogance” of assuming that adaptations to extreme conditions exhibited by Earth life will always be the most optimal.
“On Earth, there are only a few localities with hyperacidity and none as extreme as on Venus, so there would not be much motivation for Earth life to evolve such adaptations,” Schulze-Makuch says. “On Venus, however, life might have had up to one billion years’ time to evolve such adaptations” as a runaway greenhouse effect gradually pushed the once temperate world into its present hellish state.
The Private Sector Steps Up
In the meantime spotting a potential biosignature on Venus is spurring a private-sector response. For example, Breakthrough Initiatives, a privately funded space science effort, is sponsoring a study by top-tier specialists that will seek to clarify the parameters of primitive life dwelling within Venus’s hostile skies.
The group is led by Sara Seager, an astrophysicist at the Massachusetts Institute of Technology and a collaborator on the phosphine-discovery studies. Its charge is “to push the envelope to try to understand what kind of life could exist in the very harsh Venus atmosphere and what further evidence for life a mission to Venus could search for,” she says.
Then there is Rocket Lab, a private American aerospace manufacturer and launch service for small satellites that is slated to conduct its first deep-space mission next year: sending a NASA payload to the moon. That lunar foray will only be a prelude to an even more ambitious endeavor: a pint-sized Venusian atmospheric probe to seek additional evidence for or against potential life there. Riding on one of the company’s Electron rockets onboard its small, proprietary Photon spacecraft, the mission could lift off as early as 2023.
“I'm completely fascinated by Venus,” says Rocket Lab’s founder and chief executive Peter Beck. “There is so much we can learn about a planet that is so analogous to Earth. We understand life as it exists here on Earth, but life on Venus could be something really at odds with everything we know. If we can prove life exists off Earth, then it’s fair to assume it could be prolific throughout the universe.”
Moreover, beyond the search for life, Beck says, Venus could offer another message. “There’s a huge amount we can unpack about climate change from studying Venus,” he says. “Venus was once possibly not to dissimilar to Earth, with oceans and water. Then it was enveloped in a shroud of carbon dioxide that drove a runaway greenhouse effect, pushing temperatures to extremes and turning the planet into the hellscape it is today. By taking a closer look at Venus, we might just be able to provide a glimpse into what could lay ahead for Earth in the case of runaway climate change.”
Is It Life? Wait and See
The purported phosphine detection is indeed interesting, says Chris McKay, an astrobiologist at NASA’s Ames Research Center. But he questions whether phosphine could actually be considered a biosignature.
The claims of phosphine on Venus hinge on the interpretation of a single feature, a dip in a spectrum of the planet’s atmosphere that was attributed to the gas’s presence. Researchers saw the phosphine line in spectra gathered by two independent facilities: the James Clerk Maxwell Telescope on Mauna Kea in Hawaii and the Atacama Large Millimeter/submillimeter Array observatory in Chile. That dual detection is a boon for arguments that the finding is genuine, McKay says, but “a robust detection would have several spectral features that are in relative agreement” rather than just one.
Advocates of airborne biology on Venus make a good case that there are no natural sources of phosphine on the planet, McKay adds. Then again, an equally compelling case can be made that because they are impoverished of water and enriched in sulfuric acid, the the so-called habitable cloud zones are, in fact, not at all suitable for life. “So it would be premature to jump to any conclusion,” he says. “Basically, we have no coherent theory for how phosphine could be present on Venus.... Don’t bet the farm on life just yet. It may not be phosphine. And if it is, it may not be biotic.”
Like McKay, another expert firmly in the “wait and see” contingent is Robert Grimm, a program director in planetary science at SwRI. He sketches out a checklist of what researchers should do next: “Work out how good the observation is. Vet their claim that there can be no abiotic mechanisms. Look at the NASA queue and see what fits,” Grimm says. “If they exist, the bugs have been there for at least hundreds of millions of years. They can wait another decade.”


scientificamerican--2020-09-23--What COVID-19 Reinfection Means for Vaccines

The question of whether we can be reinfected with COVID-19 has been resolved .
In August , genome sequencing confirmed that a 33-year-old man in Hong Kong had indeed been infected by the same virus a second time .
So too was the case for a 25-year-old man in the United States , though the originating case study has yet to be peer reviewed .
This strengthens earlier reports that have surfaced periodically throughout the pandemic .
Most were in China and South Korea , and some in the U.S. None of these were ever verified in laboratory , leaving @ @ @ @ @ @ @ negatives had simply confounded test results .
A new surge of similarly anecdotal reports is cropping up across Europe and India .
If SARS-CoV-2 , the virus that causes COVID-19 , follows the precedent set by its coronavirus cousins , reinfection will soon become the rule , rather than the exception .
The ability of common-cold-causing coronaviruses endemic to humans to infect the same person multiple times has been documented in studies going back decades and , more recently , in a detailed 2018 study conducted by researchers collaborating in the Netherlands and @ @ @ @ @ @ @ now that we know SARS-CoV-2 also possesses the ability to reinfect , can guide our attempts to answer the questions that remain—namely , how often we can expect to be reinfected , whether a second infection will induce symptoms more mild or severe than what came before , and what this all means for our ability to create a COVID-19 vaccine .
Early evidence of reinfection dates back to series of experiments conducted in the late 1970s and .
Healthy volunteers were exposed to a coronavirus one year , develop a cold , @ @ @ @ @ @ @ year later , the cycle repeated for the majority of participants—as many as two thirds , as was the case in a study published in 1990 .
Some of these are the same coronaviruses we battle year in and year out .
The Kenya study , which incorporated gene sequencing methods , corroborates and elaborates on these findings .
Carried out across rural hospitals and households in Kilifi County , Kenya , the study tracked the circulation of multiple coronaviruses throughout the community over a span of six years .
Nearly 30 percent @ @ @ @ @ @ @ the virus once experienced a second infection , while about 10 percent went on to contract it a third time—and at least one person was infected four times .
Some were reinfected in as little as three months after their first diagnosis , and for a surprising number of those reinfections , viral load actually increased .
If and when reinfections with COVID-19 become the norm , the majority of people will weather the virus as they would any other cold .
You get it , and after a certain period of time @ @ @ @ @ @ @ vulnerable to its return .
The key difference is that seasonal cold-causing viruses rarely cause lethal disease , while COVID-19 does at rates of 1–5 percent , depending on the health status of those it affects .
Why reinfection occurs so consistently across the coronavirus family , we don ’ t know .
But what has become increasingly clear is that the defenses we mount against the virus during and after primary infection seem to fade relatively quickly—a disappearing act that doesn ’ t bode well for our prospects of achieving so-called herd @ @ @ @ @ @ @ .
I ’ ve written before that , as a strategy , counting on herd immunity is reckless and ineffective .
Immunity , we must remember , isn ’ t a switch the body can flip on and off at will .
It consists of a complex series of reactions and interactions that are difficult to observe and detangle .
One set of mechanisms is innate and at work constantly , irrespective of the threat at hand .
Another is adaptive , chemically generated at the moment of encounter to attack a specific @ @ @ @ @ @ @ explanation of reinfection is that human coronaviruses are adept at tampering with our adaptive immunity , ensuring our long-term response to the virus isn ’ t as powerful or enduring as it is for many other viruses .
Two defenses in particular , killer T cells and B cells ( antibody-producing plasma cells ) , are responsible for sustaining this momentum .
When viral infection occurs , a type of antibody called IgM appears within one to two weeks .
IgM antibodies mobilize against the virus , then begin to disappear in the @ @ @ @ @ @ @ weeks after an infection has cleared , IgG antibodies appear .
It is the case for many viruses , including those that cause most childhood diseases , that reasonably high levels of IgG antibodies persist for many years .
This is not the case for human coronaviruses .
The 1990 study was among the first to monitor antibody levels in addition to reinfection .
Although increases were detected within the three weeks following primary infection , within three months they declined sharply .
Longer-term studies of recovered SARS and MERS patients also saw @ @ @ @ @ @ @ to three-year period .
Thanks to months of intensive research , we now have a relatively clear picture of the antibody response triggered specifically by SARS-CoV-2 .
Those who are asymptomatic produce low—sometimes even undetectable—levels of antibodies , even when the virus has been cleared .
For the most part , studies show that concentrations of these antibodies diminish rapidly , suggesting that asymptomatic individuals may be the most susceptible to reinfection .
Those who fall ill , and particularly those who fall seriously ill , produce greater amounts of antibodies that persist @ @ @ @ @ @ @ would seem , upon first glance , to offer greater protection , too .
The Kenya study on endemic human coronaviruses , however , offers evidence to the contrary that may turn out to be applicable to SARS-CoV-2 .
In some patients , it was found that high antibody levels actually potentiated infection rather than preventing or mitigating it—leaving open the possibility that no one , regardless of the nature of their primary infection , is totally safe from reinfection .
There may also be differences from population to population .
While the @ @ @ @ @ @ @ against SARS-CoV-2 fade over time , one recent Icelandic study , published in the New England Journal of Medicine early this month , found that more than 90 percent of the several thousands of people surveyed still had them four months after their initial diagnosis .
Vaccines , once injected , don ’ t shield the body from infection .
Instead , they equip the immune system with a sophisticated alarm system—one that will trigger a vigorous and rapid response whenever the invading virus sets off the alarm .
Immune memory cells , @ @ @ @ @ @ @ soon as the alarm sounds , allow the body to target and clear out the virus in a matter of days , rather than weeks .
This process of short-circuiting an intruder ’ s life cycle is typical—and successful—for many of the vaccinations we receive as children , including measles , mumps and polio .
These vaccines mimic a natural immune response , to the effect of developing long-term and in some cases lifelong immunity to reinfection .
The natural immune response to coronaviruses , however , is far more complex .
Since @ @ @ @ @ @ @ to reinfect us , we can infer with reasonable confidence that natural immunity won ’ t defend us against it in the long term .
Based on what we know about our immunity against COVID-19 and coronaviruses at large , there are three questions that developers of COVID-19 vaccines—and those of us who will be queuing up to receive them—must contemplate if we ’ re to create one that is safe , effective and protective for a long duration .
The first question is how long any immunity , whether natural or vaccine-mediated @ @ @ @ @ @ @ more difficult question is whether a strong immune response can , in some , facilitate future infections , and if reinfection does occur , whether it might increase , rather than decrease , the amount of virus in the body .
The third and final question concerns the mechanisms by which coronaviruses reestablish infection in a person who has already been infected once before .
One possibility is that they inactivate our memory cells—the equivalent of disconnecting the alarm .
This is what the measles virus does upon first infection : target and @ @ @ @ @ @ @ now , whether this is the case for coronaviruses is unknown .
If SARS-CoV-2 doesn ’ t wipe out memory response upon reinfection , there is more or less a clear path forward for vaccine development .
Over time , we may have to create new generations of vaccines because of antigenic drift , as we do with the flu .
Aside from the fact that we may have to revaccinate people amid fading immunity , barring any other complications a vaccine will be able to protect us from reinfection .
If SARS-CoV-2 @ @ @ @ @ @ @ , however , we might be in trouble .
There remains much we don ’ t know about COVID-19 specifically and human coronaviruses at large .
What is clear at this moment is that reinfection and the mechanisms that drive it are a key piece of this puzzle—one we can ’ t leave out , and one that will bedevil our efforts for months and years to come as we struggle to put this genie back in its bottle .

The question of whether we can be reinfected with COVID-19 has been resolved. In August, genome sequencing confirmed that a 33-year-old man in Hong Kong had indeed been infected by the same virus a second time. So too was the case for a 25-year-old man in the United States, though the originating case study has yet to be peer reviewed.
This strengthens earlier reports that have surfaced periodically throughout the pandemic. Most were in China and South Korea, and some in the U.S. None of these were ever verified in laboratory, leaving open the possibility that false positives or negatives had simply confounded test results. A new surge of similarly anecdotal reports is cropping up across Europe and India.
If SARS-CoV-2, the virus that causes COVID-19, follows the precedent set by its coronavirus cousins, reinfection will soon become the rule, rather than the exception. The ability of common-cold-causing coronaviruses endemic to humans to infect the same person multiple times has been documented in studies going back decades and, more recently, in a detailed 2018 study conducted by researchers collaborating in the Netherlands and Kenya.
This body of research, now that we know SARS-CoV-2 also possesses the ability to reinfect, can guide our attempts to answer the questions that remain—namely, how often we can expect to be reinfected, whether a second infection will induce symptoms more mild or severe than what came before, and what this all means for our ability to create a COVID-19 vaccine.
TAMPERING WITH IMMUNE MEMORY
Early evidence of reinfection dates back to series of experiments conducted in the late 1970s and 1980s . Healthy volunteers were exposed to a coronavirus one year, develop a cold, and recover. When exposed again a year later, the cycle repeated for the majority of participants—as many as two thirds, as was the case in a study published in 1990. Some of these are the same coronaviruses we battle year in and year out.
The Kenya study, which incorporated gene sequencing methods, corroborates and elaborates on these findings. Carried out across rural hospitals and households in Kilifi County, Kenya, the study tracked the circulation of multiple coronaviruses throughout the community over a span of six years. Nearly 30 percent of those who caught one variant of the virus once experienced a second infection, while about 10 percent went on to contract it a third time—and at least one person was infected four times. Some were reinfected in as little as three months after their first diagnosis, and for a surprising number of those reinfections, viral load actually increased.
If and when reinfections with COVID-19 become the norm, the majority of people will weather the virus as they would any other cold. You get it, and after a certain period of time your body forgets it, leaving you vulnerable to its return. The key difference is that seasonal cold-causing viruses rarely cause lethal disease, while COVID-19 does at rates of 1–5 percent, depending on the health status of those it affects.
Why reinfection occurs so consistently across the coronavirus family, we don’t know. But what has become increasingly clear is that the defenses we mount against the virus during and after primary infection seem to fade relatively quickly—a disappearing act that doesn’t bode well for our prospects of achieving so-called herd immunity over a longer period of time. I’ve written before that, as a strategy, counting on herd immunity is reckless and ineffective. Immunity, we must remember, isn’t a switch the body can flip on and off at will. It consists of a complex series of reactions and interactions that are difficult to observe and detangle. One set of mechanisms is innate and at work constantly, irrespective of the threat at hand. Another is adaptive, chemically generated at the moment of encounter to attack a specific intruder in specific ways.
A potential explanation of reinfection is that human coronaviruses are adept at tampering with our adaptive immunity, ensuring our long-term response to the virus isn’t as powerful or enduring as it is for many other viruses. Two defenses in particular, killer T cells and B cells (antibody-producing plasma cells), are responsible for sustaining this momentum. When viral infection occurs, a type of antibody called IgM appears within one to two weeks. IgM antibodies mobilize against the virus, then begin to disappear in the months that follow. Two to three weeks after an infection has cleared, IgG antibodies appear.
It is the case for many viruses, including those that cause most childhood diseases, that reasonably high levels of IgG antibodies persist for many years. This is not the case for human coronaviruses. The 1990 study was among the first to monitor antibody levels in addition to reinfection. Although increases were detected within the three weeks following primary infection, within three months they declined sharply. Longer-term studies of recovered SARS and MERS patients also saw the antibody responses dwindled over a two- to three-year period.
Thanks to months of intensive research, we now have a relatively clear picture of the antibody response triggered specifically by SARS-CoV-2. Those who are asymptomatic produce low—sometimes even undetectable—levels of antibodies, even when the virus has been cleared. For the most part, studies show that concentrations of these antibodies diminish rapidly, suggesting that asymptomatic individuals may be the most susceptible to reinfection. Those who fall ill, and particularly those who fall seriously ill, produce greater amounts of antibodies that persist for longer amounts of time—an outcome that would seem, upon first glance, to offer greater protection, too.
The Kenya study on endemic human coronaviruses, however, offers evidence to the contrary that may turn out to be applicable to SARS-CoV-2. In some patients, it was found that high antibody levels actually potentiated infection rather than preventing or mitigating it—leaving open the possibility that no one, regardless of the nature of their primary infection, is totally safe from reinfection. There may also be differences from population to population. While the majority of studies have found that antibodies against SARS-CoV-2 fade over time, one recent Icelandic study, published in the New England Journal of Medicine early this month, found that more than 90 percent of the several thousands of people surveyed still had them four months after their initial diagnosis.
IMPLICATIONS FOR VACCINES
Vaccines, once injected, don’t shield the body from infection. Instead, they equip the immune system with a sophisticated alarm system—one that will trigger a vigorous and rapid response whenever the invading virus sets off the alarm. Immune memory cells, trained by the vaccine to mobilize as soon as the alarm sounds, allow the body to target and clear out the virus in a matter of days, rather than weeks. This process of short-circuiting an intruder’s life cycle is typical—and successful—for many of the vaccinations we receive as children, including measles, mumps and polio. These vaccines mimic a natural immune response, to the effect of developing long-term and in some cases lifelong immunity to reinfection.
The natural immune response to coronaviruses, however, is far more complex. Since the virus does have a well-documented ability to reinfect us, we can infer with reasonable confidence that natural immunity won’t defend us against it in the long term. Based on what we know about our immunity against COVID-19 and coronaviruses at large, there are three questions that developers of COVID-19 vaccines—and those of us who will be queuing up to receive them—must contemplate if we’re to create one that is safe, effective and protective for a long duration.
The first question is how long any immunity, whether natural or vaccine-mediated, will last. The second and more difficult question is whether a strong immune response can, in some, facilitate future infections, and if reinfection does occur, whether it might increase, rather than decrease, the amount of virus in the body. The third and final question concerns the mechanisms by which coronaviruses reestablish infection in a person who has already been infected once before. One possibility is that they inactivate our memory cells—the equivalent of disconnecting the alarm. This is what the measles virus does upon first infection: target and kill memory B cells specifically. For now, whether this is the case for coronaviruses is unknown.
If SARS-CoV-2 doesn’t wipe out memory response upon reinfection, there is more or less a clear path forward for vaccine development. Over time, we may have to create new generations of vaccines because of antigenic drift, as we do with the flu. Aside from the fact that we may have to revaccinate people amid fading immunity, barring any other complications a vaccine will be able to protect us from reinfection. If SARS-CoV-2 it does tamper with our immune memory, however, we might be in trouble.
There remains much we don’t know about COVID-19 specifically and human coronaviruses at large. What is clear at this moment is that reinfection and the mechanisms that drive it are a key piece of this puzzle—one we can’t leave out, and one that will bedevil our efforts for months and years to come as we struggle to put this genie back in its bottle.


scientificamerican--2020-09-23--China Says It Will Stop Releasing CO2 within 40 Years

China pledged yesterday to stop releasing carbon emissions before 2060 in a surprise move that catapults it ahead of U.S. ambitions on climate change and instantly raised questions about whether it can radically alter its status as the world 's top emitter within 40 years .
Chinese President Xi Jinping 's announcement at the U.N. General Assembly won accolades from European leaders who have pressed China for stronger climate action , and from climate advocates who are hopeful it will lead developing countries to follow suit .
Xi told the United Nations yesterday : `` We aim to have CO @ @ @ @ @ @ @ neutrality before 2060 . ''
He pledged that China would `` scale up '' its commitment to the Paris Agreement by `` adopting more rigorous policies and measures . ''
The night before Xi 's unexpected announcement , China 's top climate diplomat at the Paris summit in 2015 , Xie Zhenhua , said during an event hosted by the Asia Society that China would update its global promise on climate change , known as a nationally determined contribution , or NDC , by the end of this year .
That ended years @ @ @ @ @ @ @ in the Paris Agreement 's second phase , during which countries are supposed to ratchet up their commitments to reduce carbon dioxide .
Xi 's pledge to peak emissions `` before 2030 '' is a subtle repackaging of China 's 2015 Paris goal , which promised a peak `` by 2030 . ''
Either way , it 's been anticipated that China would stop increasing its carbon output within this decade , even as its use of coal has rebounded from previous lows .
Its 2060 carbon neutrality pledge , while surprising , @ @ @ @ @ @ @ Paris Agreement calls on all nations to stop emitting greenhouse gases by 2050 to prevent 2 degrees Celsius of warming .
Developed countries and regions like the European Union , its member states and Canada have set net-zero deadlines of 2050 or earlier .
The 2060 pledge marks the first time China and its top leader have made a long-term commitment to reducing emissions , said Gang He , a professor who studies energy and climate policy at Stony Brook University .
`` This is huge given China 's energy-related carbon emission accounted @ @ @ @ @ @ @ energy-related carbon emissions in 2019 and its continuing growth of [ gross domestic product ] and growing population of middle class , '' he said .
China has long argued that it should have more leeway to increase its emissions as it grows its economy .
But it also strengthened the prospects for a global climate deal in 2015 when it helped demolish the so-called firewall between rich and poor nations that was once a fixture in climate talks : the idea that nations that had grown rich by releasing carbon dioxide should @ @ @ @ @ @ @ China was not among that group , and its willingness to cut its own emissions helped change the tone of climate negotiations .
Now , China 's move to end its emissions altogether could help persuade other major developing economies , like India and Indonesia , to do the same , according to analysts .
`` This is going to create something of a precedent that climate advocates can point to when they 're talking with the leaders of other emerging economies , '' said David Livingston , a senior analyst with the @ @ @ @ @ @ @ , 'Look , China has continued to break down the firewall that once existed . '
'' Xi 's statement came minutes after President Trump lambasted China as a global pariah on the environment in his own U.N. address .
Touting the United States ' `` exceptional environmental record , '' Trump decried China 's world-leading mercury emissions and its carbon emissions , which he said `` are nearly twice what the U.S. has , and it 's rising fast , '' and the fact that U.S. carbon emissions from energy production declined @ @ @ @ @ @ @ last year .
Those who attack the United States on the environment `` while ignoring China 's rampant pollution are not interested in the environment , '' Trump said .
`` They only want to punish America , and I will not stand for it . ''
All of Trump 's assertions are mostly technically correct .
China is the world 's leading emitter of mercury by an overwhelming margin , according to a 2018 report by the U.N .
Environment Programme .
China 's carbon emissions did increase slightly last year as @ @ @ @ @ @ @ say the broader trend is a plateau , while U.S. energy-related emissions declined by nearly 3 % , according to the International Energy Agency in Paris .
No other country saw its emissions drop as much .
But declines in U.S. emissions over the last decade are linked to a market-driven shift from coal to natural gas for power production and to Obama-era environmental policies that have been largely dismantled by Trump .
Meanwhile , China is pledging new actions in the future .
Xie said at the Asia Society event this week @ @ @ @ @ @ @ economy would shrink coal 's share of the Chinese power mix for the years 2021 and 2025 .
Observers say China 's announcement is a diplomatic olive branch to the European Union , in a year when European leaders have been increasingly critical of China on issues from trade to human rights .
Only last week , Xi held a long-distance meeting with German Chancellor Angela Merkel , European Council President Charles Michel and European Commission President Ursula von der Leyen in which the E.U .
leaders urged China to update its climate @ @ @ @ @ @ @ And E.U .
leaders are planning an event with additional commitments for Dec. 12 , the fifth anniversary of the Paris deal , when China is likely to make additional announcements .
`` By making these sweeping symbolic gestures and concessions on climate , they buy themselves quite a bit of goodwill with Europe and help to keep the E.U .
on side in a year in which China does n't have many public diplomacy successes to brag about , '' said Livingston .
Alden Meyer , director of strategy at the Union @ @ @ @ @ @ @ for global institutions permeated Xi 's U.N. statement beyond just support for climate action .
`` He 's kind of posturing China as a guardian of multilateral cooperation , which we know is not always the case , but it 's clearly the decision they 've made to lay this down as a marker , '' he said .
`` And that 's clearly drawing a contrast with President Trump . ''
Trump has moved to withdraw the United States from the Paris Agreement , a process that will be complete the day @ @ @ @ @ @ @ has also stopped funding the World Health Organization and has taken other adversarial positions on international institutions .
China was long expected to wait to offer new climate commitments until the results of the U.S. election were known , but yesterday 's announcement changes that calculus .
Now , if Joe Biden , the Democratic presidential nominee , wins in November , he will feel pressure to quickly offer ambitious Paris targets and a net-zero commitment rather than banding together with the European Union to push China to act , said Livingston of @ @ @ @ @ @ @ `` In a Trump scenario , this solidifies the collaboration with the E.U.
, not just on this but in defense of multilateralism more broadly . ''
But there are many unknowns about the scope of China 's climate plans .
Questions abound about how and when China plans to draw down coal use ; whether coal capacity that has come online in recent years is to be offset with the retirement of older , dirtier , coal-fired power plants ; and whether China will slow its funding of fossil fuel-based projects in @ @ @ @ @ @ @ Road Initiative ( see related story ) .
`` There 's a lot of devil-in-the-details here , '' Meyer said .
China has a mixed record when it comes to greening its economy .
Beijing has adopted an emissions trading program for its power plants ; has aggressively pursued a renewables build-out ; and is pushing to electrify freight , taxis and public transit in attempts to improve the country 's air quality .
The city of Beijing , alone , is planning to convert 20,000 taxis to electric vehicles by year 's @ @ @ @ @ @ @ for Energy Studies .
But Chinese leaders have also resorted to many of their old strategies to revive the economy from the devastation wrought by the coronavirus pandemic .
The country announced 48 gigawatts of new coal capacity in the first half of 2020 , more than was announced in all of 2019 , as part of a stimulus effort aimed at propping up industrial production .
China now has 252 GW of coal in planning or under construction , according to Global Energy Monitor , or more than the total coal capacity @ @ @ @ @ @ @ — at the end of 2019 .
The new coal plants risk locking in emissions for decades to come and complicating China 's path to net-zero carbon , analysts said .
`` That is not just a wrong direction for climate .
It is also a wrong direction given how much the prices for wind , solar and energy storage has fallen , '' said Daniel Kammen , an energy professor at the University of California , Berkeley , and a former Obama administration official .
The dynamic highlights the long-standing tension between @ @ @ @ @ @ @ ' economic priorities , analysts said .
They nevertheless said Xi 's announcement marks a significant statement of intent from the Chinese president and raises expectations for the role of green initiatives in the country 's next five-year plan , which is slated to be announced in March .
`` My WeChat is covered with this news .
We did n't expect him to announce this , '' said Fei Meng , who leads Chinese policy at Energy Innovation , a think tank that advocates for clean energy .
`` It is good @ @ @ @ @ @ @ has a big impact on the economy .
It is very , very important that President Xi can announce this to the world . ''
China 's emissions more than doubled between 2000 and 2008 , growing from about 3.4 metric gigatons to 7.4 metric gigatons , according to BP PLC 's Statistical Review of World Energy .
The pace of emissions growth has moderated in recent years .
BP estimates that China 's emissions growth averaged 2.6 % between 2008 and 2018 .
China now accounts for 28 % of global greenhouse @ @ @ @ @ @ @ emitter : the United States , at 15 % .
Still , many analysts said the country should easily be able to peak its emissions before 2030 .
Reaching that goal by 2060 will require a massive makeover of China 's economy , said Zeke Hausfather , a climate scientist at the Breakthrough Institute .
The pledge is largely consistent with the Paris Agreement 's goal of halting the rise of global temperatures before it reaches 2 degrees by century 's end , he said .
`` If they are serious about this @ @ @ @ @ @ @ news in the last decade in terms of what will bend down global emissions , '' Hausfather said .
Reprinted from Climatewire with permission from E & E News .
E & E provides daily coverage of essential energy and environmental news atwww.eenews.net .

China pledged yesterday to stop releasing carbon emissions before 2060 in a surprise move that catapults it ahead of U.S. ambitions on climate change and instantly raised questions about whether it can radically alter its status as the world's top emitter within 40 years.
Chinese President Xi Jinping's announcement at the U.N. General Assembly won accolades from European leaders who have pressed China for stronger climate action, and from climate advocates who are hopeful it will lead developing countries to follow suit.
Xi told the United Nations yesterday: "We aim to have CO 2 emissions peak before 2030 and achieve carbon neutrality before 2060."
He pledged that China would "scale up" its commitment to the Paris Agreement by "adopting more rigorous policies and measures."
The night before Xi's unexpected announcement, China's top climate diplomat at the Paris summit in 2015, Xie Zhenhua, said during an event hosted by the Asia Society that China would update its global promise on climate change, known as a nationally determined contribution, or NDC, by the end of this year.
That ended years of speculation about whether China would participate in the Paris Agreement's second phase, during which countries are supposed to ratchet up their commitments to reduce carbon dioxide.
Xi's pledge to peak emissions "before 2030" is a subtle repackaging of China's 2015 Paris goal, which promised a peak "by 2030." Either way, it's been anticipated that China would stop increasing its carbon output within this decade, even as its use of coal has rebounded from previous lows.
Its 2060 carbon neutrality pledge, while surprising, puts it behind global standards. The Paris Agreement calls on all nations to stop emitting greenhouse gases by 2050 to prevent 2 degrees Celsius of warming. Developed countries and regions like the European Union, its member states and Canada have set net-zero deadlines of 2050 or earlier.
The 2060 pledge marks the first time China and its top leader have made a long-term commitment to reducing emissions, said Gang He, a professor who studies energy and climate policy at Stony Brook University.
"This is huge given China's energy-related carbon emission accounted for about 28.8% of the global energy-related carbon emissions in 2019 and its continuing growth of [gross domestic product] and growing population of middle class," he said.
China has long argued that it should have more leeway to increase its emissions as it grows its economy. But it also strengthened the prospects for a global climate deal in 2015 when it helped demolish the so-called firewall between rich and poor nations that was once a fixture in climate talks: the idea that nations that had grown rich by releasing carbon dioxide should shoulder the burden of reducing it.
China was not among that group, and its willingness to cut its own emissions helped change the tone of climate negotiations.
Now, China's move to end its emissions altogether could help persuade other major developing economies, like India and Indonesia, to do the same, according to analysts.
"This is going to create something of a precedent that climate advocates can point to when they're talking with the leaders of other emerging economies," said David Livingston, a senior analyst with the Eurasia Group. "They can say, 'Look, China has continued to break down the firewall that once existed.'"
Xi's statement came minutes after President Trump lambasted China as a global pariah on the environment in his own U.N. address. Touting the United States' "exceptional environmental record," Trump decried China's world-leading mercury emissions and its carbon emissions, which he said "are nearly twice what the U.S. has, and it's rising fast," and the fact that U.S. carbon emissions from energy production declined more than those of any other country last year.
Those who attack the United States on the environment "while ignoring China's rampant pollution are not interested in the environment," Trump said. "They only want to punish America, and I will not stand for it."
All of Trump's assertions are mostly technically correct.
China is the world's leading emitter of mercury by an overwhelming margin, according to a 2018 report by the U.N. Environment Programme. China's carbon emissions did increase slightly last year as more coal came online, though experts say the broader trend is a plateau, while U.S. energy-related emissions declined by nearly 3%, according to the International Energy Agency in Paris. No other country saw its emissions drop as much.
But declines in U.S. emissions over the last decade are linked to a market-driven shift from coal to natural gas for power production and to Obama-era environmental policies that have been largely dismantled by Trump.
Meanwhile, China is pledging new actions in the future.
Xi vs. Trump
Xie said at the Asia Society event this week that the five-year plan for the Chinese economy would shrink coal's share of the Chinese power mix for the years 2021 and 2025.
Observers say China's announcement is a diplomatic olive branch to the European Union, in a year when European leaders have been increasingly critical of China on issues from trade to human rights.
Only last week, Xi held a long-distance meeting with German Chancellor Angela Merkel, European Council President Charles Michel and European Commission President Ursula von der Leyen in which the E.U. leaders urged China to update its climate goals and set a net-zero deadline.
And E.U. leaders are planning an event with additional commitments for Dec. 12, the fifth anniversary of the Paris deal, when China is likely to make additional announcements.
"By making these sweeping symbolic gestures and concessions on climate, they buy themselves quite a bit of goodwill with Europe and help to keep the E.U. on side in a year in which China doesn't have many public diplomacy successes to brag about," said Livingston.
Alden Meyer, director of strategy at the Union of Concerned Scientists, noted that support for global institutions permeated Xi's U.N. statement beyond just support for climate action.
"He's kind of posturing China as a guardian of multilateral cooperation, which we know is not always the case, but it's clearly the decision they've made to lay this down as a marker," he said. "And that's clearly drawing a contrast with President Trump."
Trump has moved to withdraw the United States from the Paris Agreement, a process that will be complete the day after the Nov. 3 election. He has also stopped funding the World Health Organization and has taken other adversarial positions on international institutions.
China was long expected to wait to offer new climate commitments until the results of the U.S. election were known, but yesterday's announcement changes that calculus. Now, if Joe Biden, the Democratic presidential nominee, wins in November, he will feel pressure to quickly offer ambitious Paris targets and a net-zero commitment rather than banding together with the European Union to push China to act, said Livingston of the Eurasia Group.
Added Meyer: "In a Trump scenario, this solidifies the collaboration with the E.U., not just on this but in defense of multilateralism more broadly."
But there are many unknowns about the scope of China's climate plans.
Questions abound about how and when China plans to draw down coal use; whether coal capacity that has come online in recent years is to be offset with the retirement of older, dirtier, coal-fired power plants; and whether China will slow its funding of fossil fuel-based projects in countries that participate in its Belt and Road Initiative (see related story).
"There's a lot of devil-in-the-details here," Meyer said.
Mixed record
China has a mixed record when it comes to greening its economy.
Beijing has adopted an emissions trading program for its power plants; has aggressively pursued a renewables build-out; and is pushing to electrify freight, taxis and public transit in attempts to improve the country's air quality.
The city of Beijing, alone, is planning to convert 20,000 taxis to electric vehicles by year's end, according to the Oxford Institute for Energy Studies.
But Chinese leaders have also resorted to many of their old strategies to revive the economy from the devastation wrought by the coronavirus pandemic.
The country announced 48 gigawatts of new coal capacity in the first half of 2020, more than was announced in all of 2019, as part of a stimulus effort aimed at propping up industrial production. China now has 252 GW of coal in planning or under construction, according to Global Energy Monitor, or more than the total coal capacity of the United States — 229 GW — at the end of 2019.
The new coal plants risk locking in emissions for decades to come and complicating China's path to net-zero carbon, analysts said.
"That is not just a wrong direction for climate. It is also a wrong direction given how much the prices for wind, solar and energy storage has fallen," said Daniel Kammen, an energy professor at the University of California, Berkeley, and a former Obama administration official.
The dynamic highlights the long-standing tension between Beijing's climate goals and local governments' economic priorities, analysts said. They nevertheless said Xi's announcement marks a significant statement of intent from the Chinese president and raises expectations for the role of green initiatives in the country's next five-year plan, which is slated to be announced in March.
"My WeChat is covered with this news. We didn't expect him to announce this," said Fei Meng, who leads Chinese policy at Energy Innovation, a think tank that advocates for clean energy. "It is good at this special moment because COVID still has a big impact on the economy. It is very, very important that President Xi can announce this to the world."
China's emissions more than doubled between 2000 and 2008, growing from about 3.4 metric gigatons to 7.4 metric gigatons, according to BP PLC's Statistical Review of World Energy.
The pace of emissions growth has moderated in recent years. BP estimates that China's emissions growth averaged 2.6% between 2008 and 2018. China now accounts for 28% of global greenhouse gas emissions, almost double the next-largest emitter: the United States, at 15%.
Still, many analysts said the country should easily be able to peak its emissions before 2030.
Achieving net-zero emissions is another matter.
Reaching that goal by 2060 will require a massive makeover of China's economy, said Zeke Hausfather, a climate scientist at the Breakthrough Institute. The pledge is largely consistent with the Paris Agreement's goal of halting the rise of global temperatures before it reaches 2 degrees by century's end, he said.
"If they are serious about this, it is certainly the biggest climate news in the last decade in terms of what will bend down global emissions," Hausfather said.
Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news atwww.eenews.net.