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

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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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Different type of photosynthesis may save temperate crops from climate change

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Oct. 23 (UPI) — In many places, climate change is expected to bring hotter, drier weather. In a new study, published Friday in the journal The Plant Cell, scientists considered whether an alternative mode of photosynthesis, might yield more heat-tolerant and drought-resistant plants.

Most plants in arid and semi-arid environs use a photosynthesis method called Crassulacean acid metabolism, or CAM. Alternatively, plants in temperate environs, including crops, rely on a photosynthesis method called C3 carbon fixation.

Plants using C3 carbon fixation absorb CO2 through their leaves’ stomatal pores. The daytime process allows C3 plants to immediately convert sunlight into food. When conditions are especially hot and dry, C3 metabolism causes plants to lose too much water.

Conversely, CAM plants absorb CO2 through their stomatal pores at the night. The carbon gets stored in cells until daytime, when it is converted into food via photosynthesis. This alternative carbon fixation technique allows CAM plants to close their stomatal pores during the day to prevent excess water loss.

For the new study, researchers developed sophisticated biological models to determine whether C3 plants genetically engineered to perform CAM photosynthesis would fare better as hotter, drier weather becomes the norm.

Researchers tested their genetic engineering simulations across a variety of temperature and relative humidity conditions. The data showed that the benefits provided by a switch to CAM metabolism are influenced by the vacuolar storage capacity of a plant’s leaves, which is dictated by climate conditions.

“Moreover, our model identified an alternative CAM cycle involving mitochondrial isocitrate dehydrogenase as a potential contributor to initial carbon fixation at night,” researchers wrote in their paper. “Simulations across a range of environmental conditions show that the water-saving potential of CAM strongly depends on the daytime weather conditions.”

In other words, engineering CAM metabolism in temperature plants isn’t a cure-all. Still, authors of the new study suggest their findings will help plant scientists developed new strategies for engineering greater resiliency among C3 crops.

“Modelling is a powerful tool for exploring complex systems and it provides insights that can guide lab and field-based work,” lead study author Nadine Töpfer said in a news release.

“I believe that our results will provide encouragement and ideas for the researchers who aim to transfer the water-conserving trait of CAM plants into other species,” said Töpfer, a postdoctoral researcher at the Leibniz Institute of Plant Genetics and Crop Plant Research in Germany.



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The arrival of seabirds transformed the Falkland Islands 5,000 years ago

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Oct. 23 (UPI) — Roughly 5,000 years ago, seabirds colonized the Falkland Islands in record numbers. New research — published Friday in the journal Science Advances — suggests the seabirds arrived around the same time that the South Atlantic cooled, and their arrival shifted the ecosystems on the Falkland Islands.

Today, the remote South Atlantic islands remain a refuge for several important seabird species, including great shearwaters, black-browed albatrosses, white-chinned petrels and five species of penguins.

For a few thousand years, these burrowing and ground nesting seabirds had the islands mostly to themselves, but over the last few centuries, the birds have lost ground to sheep grazing and erosion.

In addition, sea and air temperatures in the South Atlantic have been steadily rising as a result of climate change.

To better understand how Falkland Island seabirds might cope in a warmer climate, scientists set out to study the history of climate change and ecological changes on the Falkland Islands.

By sampling peat core layers, researchers were able to reconstruct a 14,000-year record of climate and ecological shifts on the island. The data confirmed that seabirds began migrating to the islands in large numbers around the time the South Atlantic began to cool.

“Our 14,000-year record shows that seabirds established at Surf Bay during cooler climates,” lead study author Dulcinea Groff said in a news release.

“Seabird conservation efforts in the South Atlantic should be prepared for these species to move to new breeding grounds in a warmer world, and those locations may not be protected,” said Groff, who led the research while she was a doctoral student in ecology and environmental sciences at the University of Maine.

The peat layers also revealed a dramatic ecological transformation following the arrival of seabirds. Marine-derived nutrients from guano rejuvenated the island’s poor soil, allowing the establishment of tussock grasses, or bunch grasses. Ash in the peat layers showed the proliferation of grasslands across the islands led to an increase in seasonal wildfires.

Researchers suggest their work is a reminder of the important connections between disparate ecosystems, as well as an example of how quickly ecosystems can be transformed.

“Our study is unique because it documents a direct linkage across ocean and land ecosystems between top predators of the oceans — the seabirds — and island plant communities,” said Groff, now a postdoctoral researcher at the University of Wyoming. “The abrupt ecosystem shift happened within a matter of a few decades and suggests that as the climate continues to warm, it’s critical to think about where seabirds will go in the future and plan to protect those places.”

It’s not just rising temperatures that conservationists are worried about, she said.

Grasslands on the Falkland Islands have been degraded by a couple centuries of livestock grazing. The islands’ wildlife species depend on the health of the grasslands. And because the island’s tussock grass depend on bird droppings, a decline in the abundance of seabirds could have broad ecological repercussions.

“As the climate warms, seabirds may find and occupy more suitable environments elsewhere, and we should expect that the coastal grasslands will respond to the loss in nutrients from seabird guano,” said Groff.



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SpaceX launches cluster of Starlink satellites

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Oct. 24 (UPI) — SpaceX launched its Falcon 9 rocket into space Saturday morning, carrying 60 Internet satellites into orbit to help establish connections to remote areas.

The launch, which was originally scheduled for Wednesday, took off from Cape Canaveral Air Force Station. It went off without a hitch with the booster rocket safely landing on SpaceX’s drone ship in the Atlantic Ocean.

The upper stage of the Falcon 9 deployed the satellites into orbit 63 minutes after takeoff, allowing SpaceX to build on its previous successes.

SpaceX had put 180 Starlink satellites into space before Saturday’s launch. The launch was the mission’s 15th, but only the 14th with operational broadband satellites. The Starlink constellation currently boasts in excess of 800 mini satellites.

“The goal of Starlink is to create a network that will help provide internet services to those who are not yet connected, and to provide reliable and affordable Internet across the globe,” according to the Kennedy Space Center.

SpaceX was originally scheduled to launch Starlink-14 on Wednesday, but bad weather forced officials to scrub the launch. Liftoff was rescheduled for Thursday, but when a camera on the rocket’s upper stage failed, officials decided to nix the launch again.

SpaceX fans and media members have taken to referring to October as “Scrubtober” on social media, as SpaceX has been continually frustrated by poor weather and launch delays.

Despite the delays, SpaceX is inching closer to being able to offer everyday Internet users the chance to surf the web using Starlink.

Earlier this month, SpaceX founder and CEO Elon Musk tweeted that Starlink’s constellation had grown large enough to begin beta-testing the Internet service system in both the United States and southern Canada.

Earlier this week, SpaceX announced that it would offer Starlink’s broadband services free of charge to families in Texas’ Ector County Independent School District. More than a third of children and their families in the district are without Internet access.



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