The scenes were apocalyptic. On 20 July, a flash flood in Zhengzhou, a city of 10 million on the Yellow River in China, caused a low-lying, kilometer-long section of the city’s Metro Line 5 tunnel to fill with water, trapping more than 500 riders in a subway train. In real time, passengers posted terrifying videos and photos on social media sites, showing people standing in chest-deep water that was still rising. Rescuers, hampered by extensive street-level flooding, arrived 4 hours later, but 14 people did not make it out alive.

Scientists and engineers are still piecing together the chain of events that led to the tragedy, but already they are warning that the lessons go far beyond China. “The intensity and frequency of extreme weather is increasing with climate change, [and] major metropolitan areas around the world are at increased risk,” says Liu Junyan, climate risk project leader in Greenpeace East Asia’s Beijing office. Municipal drainage systems in Hong Kong or New York City “couldn’t handle so much water” either, says Chen Ji, who studies the effects of climate change on water resources at the University of Hong Kong. Just 3 days ago, several stations in the London Underground were inundated.

Many cities may not be aware of the flood hazards their decades-old subway systems face. “To date relatively little research has been carried out on the study of [flash] flooding events affecting metro systems,” Edwar Forero-Ortiz and colleagues at the Cetaqua Water Technology Centre, a private research institute in Barcelona, Spain, wrote in a July 2020 Hydrological Sciences Journal paper. Even less is known about how climate change is adding to the risks. Against that background, “I think that this flood is very important in terms of providing a warning to subway system managers” that they need to take measures to mitigate flooding, says Taisuke Ishigaki, a flood disaster specialist at Kansai University.

A new tool from the International Union for Conservation of Nature (IUCN) will detail the recovery status of threatened and endangered species, The Guardian reports. The conservation organization, which has long highlighted species in peril with its Red List, today announced its Green Status of Species list, which it hopes will catalyze conservation initiatives by highlighting successes and opportunities for future action. IUCN has now assessed 181 species using this new metric, it reports in Conservation Biology.

To determine each species’ green status, more than 200 researchers working under the auspices of IUCN compared the size and range of the current population with what they were in the past. They also assessed the impact of conservation work, how much the species’ survival still depends on human help, and to what extent the species might recover in the future. The assessed animals, plants, and fungi were then assigned a category ranging from “fully recovered” to “extinct in the wild.”

The gray wolf was among the species assessed in the new study. Although it is listed as “least concern” on the Red List, it was assigned a “largely depleted” green status category, illustrating that this once-widespread species has a long way to go before achieving full ecological recovery. On the other hand, the pink pigeon of Mauritius fell to a wild population of just 10 individuals in the early 1990s. Its green status listing of “moderately depleted” points to how successful conservation efforts have been since then, helping raise its numbers to a few hundred. A Eurasian species called the river clubtail dragonfly was dubbed “fully recovered”; it had been threatened in Western Europe by polluted waterways but has bounced back after the European Union instituted new environmental regulations.

Individuals facing the threat of COVID-19 may care most about a vaccine’s ability to forestall grave disease that could lead to a hospital bed or worse. And a number of vaccines perform that vital task well, including those from Johnson & Johnson and AstraZeneca, which are based on genetically engineered cold viruses, as well as the not-yet-authorized protein vaccine from Novavax. But for public health experts trying to halt a global pandemic, shutting down even the mildest infections is also crucial, especially as the highly infectious Delta variant surges in scores of countries. By that measure, according to a brace of new studies, the messenger RNA (mRNA) vaccines from the Pfizer-BioNTech collaboration and Moderna stand out.

“All COVID-19 vaccines are not created equal,” says Eric Topol, a physician-scientist at the Scripps Research Translational Institute. “It’s clear that the two mRNA vaccines are highly effective at preventing infection—and that others wouldn’t be expected to break the chain as well.”

The large clinical trials that persuaded governments around the world to authorize COVID-19 vaccines mostly looked at their ability to block symptomatic disease and illness severe enough to lead to hospitalization or death. Preventing all infections, including those with no symptoms at all, is “rather a neglected endpoint,” says Adeel Butt, an epidemiologist and infectious disease specialist at the Veterans Affairs Pittsburgh Healthcare System. Yet, “It’s very, very important … to break the transmission of infection,” says Butt, who also works at Weill Cornell Medicine, Qatar.

More than 100 Nobel laureates have signed a statement expressing outrage after the Chinese government intended to “bully the scientific community” earlier this year with attempts to censor two Nobel laureates during the Nobel Prize Summit, organized by the U.S. National Academy of Sciences (NAS) and the Nobel Foundation in April.

The statement alleges that staffers at the Chinese embassy in Washington, D.C., phoned NAS officials in March, and again in early April before the summit, to insist that two scheduled speakers, the Dalai Lama and Yuan Lee—a Taiwanese chemist who was awarded the Nobel Prize in Chemistry in 1986 for his work on chemical kinetics—be disinvited and not allowed to speak. An email with the same demand was received by NAS on 25 April, 1 day before the start of the summit. On all three occasions, NAS said no.

William Kearney, a NAS spokesperson, confirmed to Science that the Chinese embassy pressured NAS to remove both speakers from the agenda, “which of course, we did not do,” he says.

When Chen Siyu met a consular official at the U.S. embassy in Beijing in March to review her qualifications for a student visa, “Everything was going well,” she says—or so it seemed. Chen, who has a master’s in public health from the University of Hong Kong, had won a fully funded slot in an epidemiology Ph.D. program at the University of Florida. When the consular officer asked about her current employment, Chen explained that she had worked as an epidemiology research assistant at a major hospital for 5 years. She mentioned that the hospital is affiliated with a military medical university.

The consular officer thanked Chen for the information and moments later handed her a rejection form letter with “Other: 212(f)” ticked off from among a selection of reasons. The interview was over, as were her dreams of earning a Ph.D. in the United States.

Chen is one of a growing group of Chinese students barred from the United States based on 212(f), a clause in the decades-old Immigration and Nationality Act (INA) that allows the U.S. president to identify aliens whose entry would be “detrimental to the interests of the United States.” In May 2020, then-President Donald Trump signed a proclamation that invoked the clause to bar Chinese graduate students and postgraduate researchers with ties to an entity in China “that implements or supports China’s ‘military-civil fusion strategy.’” The proclamation exempts those working in fields that don’t contribute to that strategy—but apparently epidemiology is not among them.

Transplant physicians have worried for months that their patients might not be getting the protection they need from COVID-19 vaccines. Studies have already shown that many organ recipients don’t produce coronavirus-fighting antibodies even after two doses of the highly effective messenger RNA (mRNA) vaccines—an indication their bodies are unable to mount a strong defense against SARS-CoV-2. A study out today indicates this lack of antibodies is indeed translating to a much higher risk of “breakthrough” cases of COVID-19 among vaccinated transplant recipients.

Immunosuppressant drugs, commonly used to keep the body from rejecting a new organ, leave transplant patients more vulnerable to infections. In a previous study involving 658 transplant recipients, just 54% of patients given two doses of an mRNA vaccine developed antibodies to protect them against the pandemic coronavirus. But antibodies are only one indication of a body’s response to a vaccine. Low antibody levels are “a warning,” says Dorry Segev, a transplant surgeon with Johns Hopkins University. “It’s a signal, but it doesn’t necessarily mean that they have suboptimal protection.”

To measure that protection, he and colleagues obtained SARS-CoV-2 infection and testing data on more than 18,000 fully vaccinated recipients of large organs like kidneys or lungs at 17 transplant centers across the United States. They found that 151 of these patients caught the virus. Of those that became infected, more than half were hospitalized with COVID-19 symptoms and nearly one in 10 died.

The oddly shaped object that came whizzing past the Sun and Earth in 2017 on a trajectory from outside our Solar System prompted wild speculation. Most scientists think the cigar-shaped visitor, less than 1 kilometer long, was a comet or asteroid from a nearby star or some other cosmic flotsam. But theoretical astrophysicist Avi Loeb of Harvard University argued that ‘Oumuamua, Hawaiian for “scout,” was an alien creation—a light sail, antenna, or even a spaceship. Today he announced a plan to look for more such objects: a philanthropy-backed effort called the Galileo Project.

The effort will use existing and new telescopes to systematically look for mysterious artifacts that could be satellites hiding in Earth orbit, interstellar objects—whether natural or manufactured—and even unexplained craft in Earth’s atmosphere. “It doesn’t really matter if it’s a natural artifact or a relic. If we look, we will find something new,” Loeb says.

After Loeb published a book, Extraterrestrial: The First Sign of Intelligent Life Beyond Earth, which made the case that ‘Oumuamua was some sort of alien technology, he says several wealthy individuals got in touch—unsolicited—to offer funding for such research. Four of them ultimately donated $1.75 million, enough for him to move forward with his plans. He assembled a research team involving several well-known astronomers and researchers from other fields, although he admits not everyone he approached was receptive. “The science community should be open minded. That’s how we make progress,” Loeb says.

After intense lobbying by the Australian government, the World Heritage Committee today decided against listing the Great Barrier Reef (GBR) as “in danger,” as UNESCO had recommended in June.

“The science is clear” that the reef is in perilous condition, marine ecologist Terry Hughes of James Cook University, Townsville, tweeted in response, calling the committee decision “a travesty.”

UNESCO had recommended the GBR be listed as “in danger” not only because the reef was battered by major bleaching events in 2016, 2017, and 2020, but also because of Australia’s foot dragging in addressing climate change. But Sussan Ley, Australia’s environment minister, mounted a last-minute, global campaign to avert the move. In the run-up to the virtual meeting, officially held in Fuzhou, China, Ley contacted representatives of 18 of the 21 member countries of the World Heritage Committee either in person—by visiting Hungary, France, Spain, Bosnia and Herzegovina, Oman, and the Maldives—or virtually.

After months of spaceflight, an 8-minute planetary plunge, and weeks of Mars exploration, NASA’s Perseverance rover is beginning its primary scientific task: drilling out a finger-size core of martian rock from a former lakebed for return to Earth. If all goes well, the first drilling sample will be collected by early August, the agency announced today.

Perseverance has operated well since its February landing, and during its recent drive, the rover has turned on its autonomous navigation, allowing it to cover more terrain than when under pure human operation. The rover has also tested its rock-storage system, feeding a sampling tube that it kept in the drill bit since landing, to capture ambient contamination, back into the robotic arm in its guts. There the tube was first imaged and then sealed for storage. “The great news is that it all worked perfectly,” says Jennifer Trosper, Perseverance’s project manager at NASA’s Jet Propulsion Laboratory. “We are ready to sample.”

Now, 1 kilometer south of its landing site, Perseverance has reached the spot where it will drill what its operating team calls paver stones—flat, white, dust-coated rocks found throughout much of the floor of Jezero crater. This terrain is believed to be the oldest in the crater. But it remains unclear whether this landscape was deposited by the lake or instead formed by volcanic flows, the latter of which could capture, with radioactive elements, an accurate date of the lake’s existence. Recent close-up images taken of the paver stones fail to resolve the scenarios: The rocks are covered with sand grains and pebbles, along with some sort of purplish coating, confounding remote measurements, says Ken Farley, the mission’s project scientist and a geologist at the California Institute of Technology.

In many U.S. regions, the Delta variant of SARS-CoV-2 has caused the COVID-19 pandemic to surge once again. Last week’s 7-day average of daily new cases increased by nearly 70%, to more than 26,000; hospitalizations have jumped by more than one-third, according to the Centers for Disease Control and Prevention.

Part of the reason is that less than half of the U.S. population is fully vaccinated. Some scientists and physicians worry vaccine hesitancy is fueled by the fact that shots available in the United States—made by Pfizer and BioNTech, Moderna, and Johnson & Johnson (J&J)—have been authorized on an emergency basis but have yet to be fully approved. Antivaccine activists, talk show hosts, and far-right politicians have made the vaccines’ “experimental” nature a talking point.

Full approval from the Food and Drug Administration (FDA) could help win over skeptics, says Monica Gandhi, an infectious disease physician at the University of California, San Francisco. “It means something to people for it to be approved,” she says. “It just seems like the simplest, easiest thing we could be doing right now.”