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Tropical ecosystems face perfect storm of threats



Jan. 27 (UPI) — Both tropical forests and coral reefs are facing the triple threat of climate change, extreme weather and pressures from human activities. This perfect storm of environmental damage could do irreparable harm to some of the most diverse ecosystems on the planet, according to a new study.

For the new study, researchers analyzed the ecological effects of extreme weather, including hurricanes, floods, heatwaves, droughts and fires, on 100 different tropical forest and coral reef locations.

“Tropical forests and coral reefs are very important for global biodiversity, so it is extremely worrying that they are increasingly affected by both climate disturbances and human activities,” lead researcher Filipe França, an ecologist with Embrapa Amazônia Oriental in Brazil, said in a news release.

“Many local threats to tropical forests and coral reefs, such as deforestation, overfishing, and pollution, reduce the diversity and functioning of these ecosystems,” França said. “This in turn can make them less able to withstand or recover from extreme weather. Our research highlights the extent of the damage which is being done to ecosystems and wildlife in the tropics by these interacting threats.”

The new study, published Monday in the journal Philosophical Transactions of the Royal Society B, suggests extreme weather can destroy vegetation that provides food and habitat to vulnerable species.

“A range of post-hurricane ecological consequences have been recorded in tropical forests: the destruction of plants by these weather extremes affects the animals, birds and insects that rely on them for food and shelter,” said Guadalupe Peralta, researcher at Canterbury University in New Zealand.

In places where habitats are already fragmented by human activities, including logging and agriculture, extreme weather can have especially deleterious impacts. In some places, hurricanes and other extreme weather events have reduced animal populations by half.

With temperatures rising and extreme droughts occurring more frequently, researchers suggest tropical forests are increasingly vulnerable to wildfire. The same conditions have increased the odds of coral bleaching events.

To reduce the threats to tropical biodiversity, authors of the new study suggest policy makers must combine global efforts to curb climate change with local efforts to conserve and protect vital ecosystems.

“To achieve successful climate-mitigation strategies, we need ‘action-research’ approaches that engage local people and institutions and respect the local needs and diverse socio-ecological conditions in the tropics,” said Joice Ferreira from Embrapa Amazônia Oriental.

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Astronomers find Neptune-sized star orbiting young, nearby star



June 24 (UPI) — After looking for more than a decade, astronomers have finally found an exoplanet in the young AU Microscopii star system.

With the help of NASA’s TESS and Spitzer space telescopes, scientists identified a Neptune-sized world circling the young star, positioned just 32 light-years from our solar system.

Researchers announced the discovery on Wednesday in the journal Nature.

In addition to being so close by, AU Mic is estimated to be just 20 to 30 million years old, making it 180 times younger than our sun — offering scientists an opportunity to study the early evolution of a planetary system.

“AU Mic is a small star, with only about 50 percent of the sun’s mass,” Jonathan Gagné, a former postdoctoral researcher at the University of Montreal who is now a scientific advisor at the Rio Tinto Alcan Planetarium, said in a press release.

“These stars generally have very strong magnetic fields, which make them very active,” Gagné said. “That explains in part why it took nearly 15 years to detect the exoplanet, called AU Mic b. The numerous spots and eruptions on the surface of AU Mic hampered its detection, which was already complicated by the presence of the disc.”

For the past several years, astronomers have been using ground telescopes at NASA’s Infrared Telescope Facility to monitor the star system in infrared. The star’s fluctuating emissions are less sporadic in the infrared.

“A few years after I joined the team, we noticed a possible periodic variation in the radial velocity of AU Mic,” Gagné said. “We were thus made aware of the plausible presence of a planet around it.”

As the exoplanet completes its orbit, its gravity creates slight perturbations in the star’s radial velocity. But while the ground telescopes were able to pick up on this periodic dance of infrared light, the observations weren’t precise enough to confirm the presence of an exoplanet.

However, researchers were able to observe the Neptune-sized exoplanet using a different technique. When exoplanets pass in front of their host stars, they cause a slight dimming. Using TESS and Spitzer, astronomers measured a total of four transits of AU Mic b — two with each space observatory.

The TESS and Spitzer data confirmed the exoplanet orbits AU Mic every 8.5 days. By combining the transit data with the radial velocity data collected by NASA’s IRFT telescopes, researchers were able to estimate the exoplanet’s mass.

Finding a young planet in a young stellar system is rare, researchers say. And observing the phenomena in a stellar system so close to Earth is even more rare. The close proximity of AU Mic and AU Mic b, however, allowed astronomers to study the system using a variety of instruments — like the SPIRou spectrograph.

“This instrument, with its polarimetric capabilities, will allow us to better distinguish the effects of stellar activity, which are often confused with the signal from the planets,” said É tienne Artigau, a project scientist at University of Montréal. “This will allow us to determine the mass of AU Mic b accurately and to know if this exoplanet is more like a large Earth or a Neptune twin.”

In the future, scientists hope to use SPIRou to study the effect of AU Mic’s stellar activity on the atmosphere of AU Mic b.

Scientists also plan to compare the peculiarities the AU Mic system with nearby stellar systems, such as Beta Pictoris — one of several stars that formed at the same time and in the same place.

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Clouds make newer climate models more realistic, but also less certain



June 24 (UPI) — Efforts to improve the precision with which climate models simulate cloud processes have yielded more realistic models. New research suggests these efforts have also introduced greater uncertainty, according to a study published Wednesday in the journal Science Advances.

When the latest generation of climate models started producing results last year, researchers noticed that several models were predicting higher amounts of warming than previous models. The results of the new models inspired news headlines that suggested global warming might be worse than previously thought.

As researchers with the Coupled Model Intercomparison Project, CMIP6, soon found out, a few of the latest generation of models predicted smaller levels of warming than previous models. To identify the cause of this uncertainty, CMIP6 researchers decided some historical context was needed.

One way to measure and compare the predictions of different climate models is by calculating the equilibrium climate sensitivity, or ECS.

“It’s kind of an abstract measure, but it’s one these metrics that has been around for a long time,” Gerald Meehl, a senior scientist at the National Center for Atmospheric Research, told UPI.

Essentially, scientists double the CO2 in a model and let the simulation run its course until the climate stabilizes. Each model — and each new generation of models — produces a narrow range of warming, between 1.5 to 4.5 degrees Celsius, or 2.7 to 8.1 degrees Fahrenheit.

“This kind of range has been out there for some time, and with each successive generation of models has produced about the same range in terms of degrees,” Meehl said. “With the latest generation of models, the average warming has stayed roughly the same, but the range has gotten bigger than ever — at both the low and the high end.”

When Meehl and his colleagues asked members of the groups responsible for the 39 new CMIP6 models why they thought the ECS value got bigger, most of them pointed to clouds.

To improve the accuracy of the latest generation of climate models, scientists have worked hard to simulate small-scale cloud processes. But these efforts have introduced a variety of new interactions between clouds and tiny particles called aerosols — interactions that can produce contradictory results.

“For example, if you have polluted air, particularly sulfur dioxide, that can influence clouds. Sulfur dioxide is emitted from cars and factories, and it goes into the air and forms sulfate aerosols,” Meehl said. “When you see the sky and it looks orange and hazy, chances are that a lot of that is caused by an abundance of sulfate aerosols.”

According to Meehl, these aerosols operate as cloud condensation nuclei. When these aerosols seed clouds, they seed clouds with a lot more tiny droplets.

“That increased number of small droplets makes the cloud brighter, and it’s going to reflect more sunlight and have a cooling effect,” Meehl said.

But this phenomena, now rendered more precisely in climate models, can also yield the opposite effect.

“On the other hand, you’ve formed all these droplets in the sky, but the aerosols absorb some sunlight, warm the air, and evaporate some of the droplets and that reduces the amount of clouds,” Meehl said. “That allows a little more sun into the system, and now you have a warming effect.”

Cloud-aerosol interactions are just one example of new simulated intricacies that offer both greater realism and greater uncertainty. According to Meehl, there are a variety of interacting processes involving a variety of different cloud types at different altitudes.

“With more interacting processes, your level of uncertainty can go up,” he said.

But ECS isn’t the only way to test and compare climate models. Most climate modelers prefer to use transient climate response, or TCR.

“You increase CO2 at 1 percent per year, compounded, until the time you double the amount of carbon dioxide, which is usually about 70 years,” Meehl said.

TCR works on a smaller timescale and works more like actual climate change. When scientists calculated the TCR range for the newest generation of climate models, they got the same average warming value but a smaller range.

Meehl and his colleagues shared the ECS and TCR values produced by the latest CMIP6 models in the new paper.

In addition to putting the latest generation of climate models into historical context, Meehl hopes the new study will inspire cloud modeling improvements.

“We’re doing a better job of simulating the clouds themselves, but now we have these different feedbacks that give you more uncertainty,” he said.

Now that researchers have highlighted this uncertainty, Meehl hopes climate research institutions and the climate modeling community will work to address the issue by directing more funds to relevant observational and analysis programs.

“You can’t simulate what you don’t understand,” Meehl said.

And to understand how exactly clouds will effect climate and vice versa, in the future, scientists need more robust observational programs and better satellite measurements.

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SpaceX launch Friday would boost Starlink network to nearly 600



Astronauts return to space from U.S. soil

NASA astronauts Doug Hurley (L) and Bob Behnken, who flew the Crew Dragon spacecraft to the International Space Station, brief mission controllers about their experience in the new vehicle on June 1. Photo courtesy of NASA

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