Even if you live far from the boreal forests in Canada and Siberia, you鈥檝e likely noticed an increase in smoke from their forest fires. During major blazes in 2023, the and drifted as far south as New Orleans. These blazes have surged in the last decade 鈥� warmer summers, less snow cover in the spring, and the loss of sea ice. Experts expect that trend to continue.

Yet recent climate change projection models have not accounted for the increase. For instance, the widely used sixth , or CMIP6, released in the late 2010s, kept these fires constant at a relatively low severity.

A new 天美影视传媒-led study projects that in the next 35 years these increasing boreal fires will actually slow warming by 12% globally and 38% in the Arctic. The study is the first to identify the divergence between the observed boreal fire increase and the constant fires used in climate models. Because the aerosols in smoke brighten clouds and reflect sunlight, summer temperatures during fire season drop in northern regions, leading to reduced sea ice loss and cooler winter temperatures. This effect is despite the warming effects of the fires themselves from factors such as soot that falls on the ice.

Researchers published June 3 in Proceedings of the National Academy of Sciences.

鈥淭his study helps us begin to better project the impacts of climate change. The dramatic increase in these fires in the last years is itself a symptom of that,鈥� said lead author , a UW research associate professor of atmospheric and climate science. 鈥淚t’s important to remember that these increasing fires still have a lot of negative impacts for human health and for forest biodiversity. And if the fires continue to increase, eventually they could burn through the forests and the trend could reverse. So I wouldn鈥檛 say this is good news. But it helps us better understand nature and these trends.鈥�

Every six or seven years, climate modeling centers around the world collaborate to update their projections, using numbers going back to the 19th century and projected numbers through 2100. These data comprise things like wildfires and human-caused carbon emissions. For CMIP6, which was modeled before boreal fires became a clear anomaly, the wildfires were kept constant from 2015 to 2100.

鈥淚f you look at the time series of the fires, it starts increasing around 2015, but it really spikes in 2019 and 2021, just as this modeling was being completed,鈥� Blanchard-Wrigglesworth said. 鈥淭hose are the big years of Siberian fires. And then 2023 was the even bigger Canadian fire season.鈥�

Because climate scientists don鈥檛 expect the causes of this increase in fires to abate anytime soon, the team reran one of the CMIP6 models with a new boreal fire projection based on the recent observed trends, resulting in a four-fold increase from 2015 to 2060. This adjusted the modeling for the smoke aerosols. It also accounted for factors like the fires鈥� soot, which settles on Arctic ice and darkens it, causing it to absorb more heat from sunlight (the same way sun heats asphalt). But the increased reflection of sunlight from aerosols overwhelmed this warming.

While the fires occur only in the summers, researchers actually found a greater cooling effect in the winters, because the fires block some of the summer sun, resulting in thicker Arctic ice that lasts into the following winter.

The study found impacts far from boreal forests. The smoke cools temperatures across all seasons from the Arctic down to the latitude of Northern California at 40 degrees north. The fires also push tropical rains further south because .

The authors say future work should adjust other climate models to account for increasing boreal fires and investigate possible effects of changes in the land after fires.

鈥淚 hope our work raises awareness of this issue for further study and of the potential effects of any future human management of these remote fires,鈥� Blanchard-Wrigglesworth said. 鈥淚f the increase in boreal fires continues unabated over the next decade or two, society may decide we want to manage boreal fires more. But before we put a lot of resources toward that, we need to try to understand the possible consequences.鈥�

, of Universit茅 Catholique de Louvain, and , a UW associate professor of atmospheric and climate science, are co-authors on this paper. This research was funded by the National Science Foundation and the European Union.

For more information, contact Blanchard-Wrigglesworth at edwardbw@uw.edu.

But the Earth is very likely to exceed that change, according to new 天美影视传媒 research. A study using statistical tools shows only a 5 percent chance that Earth will warm 2 degrees or less by the end of this century. It shows a mere 1 percent chance that warming could be at or below 1.5 degrees, the target set by the 2016 Paris Agreement.

“Our analysis shows that the goal of 2 degrees is very much a best-case scenario,” said lead author , a UW professor of statistics and sociology. “It is achievable, but only with major, sustained effort on all fronts over the next 80 years.”

The , published July 31 in , show a 90 percent chance that temperatures will increase this century by 2.0 to 4.9 C.

“Our analysis is compatible with previous estimates, but it finds that the most optimistic projections are unlikely to happen,” Raftery said. “We’re closer to the margin than we think.”

The most recent report from the Intergovernmental Panel on Climate Change included future warming rates based on four scenarios for future carbon emissions. The scenarios ranged from “business-as-usual” emissions from growing economies, to serious worldwide efforts to transition away from fossil fuels.

“The IPCC was clear that these scenarios were not forecasts,” Raftery said. “The big problem with scenarios is that you don’t know how likely they are, and whether they span the full range of possibilities or are just a few examples. Scientifically, this type of storytelling approach was not fully satisfying.”

The new paper focuses instead on three quantities that underpin the scenarios for future emissions: total world population, gross domestic product per person and the amount of carbon emitted for each dollar of economic activity, known as carbon intensity.

Using statistical projections for each of these three quantities based on 50 years of past data in countries around the world, the study finds a median value of 3.2 C (5.8 F) warming by 2100, and a 90 percent chance that warming this century will fall between 2.0 to 4.9 C (3.6 to 8.8 F).

“Countries argued for the 1.5 C target because of the severe impacts on their livelihoods that would result from exceeding that threshold. Indeed, damages from heat extremes, drought, extreme weather and sea level rise will be much more severe if 2 C or higher temperature rise is allowed,” said co-author , a UW associate professor of atmospheric sciences. “Our results show that an abrupt change of course is needed to achieve these goals.鈥�

Raftery previously worked on United Nations projections for future world population. His 2014 study used Bayesian statistics, a common tool used in modern statistics, to show that world population is unlikely to stabilize this century. The planet likely will reach .

In the new study, Raftery expected to find that higher populations would increase the projections for global warming. Instead, he was surprised to learn that population has a fairly small impact. That is because most of the population increase will be in Africa, which uses few fossil fuels.

What matters more for future warming is the carbon intensity, the amount of carbon emissions produced for each dollar of economic activity. That value has dropped in recent decades as countries boost efficiency and enact standards to reduce carbon emissions. How quickly that value drops in future decades will be crucial for determining future warming.

The study finds a wide range of possible values of carbon intensity over future decades, depending on technological progress and countries’ commitments to implementing changes.

“Overall, the goals expressed in the Paris Agreement are ambitious but realistic,” Raftery said. “The bad news is they are unlikely to be enough to achieve the target of keeping warming at or below 1.5 degrees.”

The research was funded by the National Institutes of Health. Other co-authors are , a UW graduate now at Upstart Networks in Palo Alto, California; , a UW professor emeritus of economics who now holds a position at the University of California, Santa Barbara; and , a UW doctoral student in statistics.

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For more information, contact Raftery at 206-543-4505 or raftery@uw.edu and Frierson at 206-685-7364 or dargan@uw.edu. Note: Raftery is in Baltimore and best reached via email.

NIH grants: HD054511, HD070936

Now atmospheric scientists at the 天美影视传媒 have set the new temperature record to an .

This is their second project to convert scientific data to an audio track, a process known as .

The notes represent global compiled by NASA and National Oceanic and Atmospheric Administration from 1880 to the just-released 2016 data. Each note is the yearly average of temperatures during that year. For about a century, the notes wobble around. Then the music pauses in 1977 for some narration.

“We picked 1977 for two reasons,” said co-creator , a UW associate professor of atmospheric sciences. “First, that is when global warming really kicked in. Also that’s the year Exxon scientists told their management that CO2 from fossil fuels is the main way humans cause climate change.”

The past four decades have a rising tune, finishing with a piercing squeal for 2016.

Last year, Frierson and doctoral student turned the Keeling Curve, a 58-year record of global carbon dioxide levels, into a . Now they are turning to temperatures, which are showing a similar upward trend. Global temperatures are rising, as anticipated, following the addition of heat-trapping gas in the Earth’s atmosphere.

“The prediction of higher temperatures from fossil fuel burning was well before most of it was observed,” Frierson added. “That is a message that I’d really like to get across with this project.”

The new temperature milestone drew international media attention, especially with continued questions about the link between greenhouse emissions and global climate.

“The string of records reflect the fact that we are going down a path that is dangerous and well-described,” UW oceanographer Sarah Myhre, who studies prehistoric climate, told .

The sonification is another way for people to experience and interpret the observations for themselves.

“By listening to Earth’s temperature rise, we hope people will be in a better position to judge fact from fiction when they hear people deny that humans are influencing global climate,” Twedt said.

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For more information, contact Frierson at dargan@uw.edu or 206-685-7364 and Twedt at jtwedt@uw.edu.

The video project was done by , a UW doctoral student in atmospheric sciences, and , a UW associate professor of atmospheric sciences and amateur musician.

Their techno soundtrack maps musical notes to the , a 58-year record of carbon dioxide measured high in the atmosphere at the Mauna Loa Observatory in Hawaii.

Twedt uses the Python open-source programming language for her climate research, and wanted to try pyknon, a software tool that turns data into musical notes. She and Frierson immediately picked the carbon dioxide record at Mauna Loa.

“The Keeling Curve was the one that we went to first because it’s so important for climate change, and I don’t think people know that,” Frierson said. “If you understand the Keeling Curve, you kind of get the story of climate change.”

American scientist Charles David Keeling was one of the first to notice that burning of fossil fuels was causing carbon dioxide to build up in the atmosphere. When Keeling began his project in 1958 the global carbon dioxide level was about 337 parts per million, already up from the preindustrial levels of about 280 parts per million. The most remote parts of the planet crossed the threshold this year, while world leaders pledge to try to do something to slow the quickening rise of the heat-trapping gas.

“The atmosphere seems so big, it seems impossible that we’re changing it, but we are,” Frierson said.

Frierson composed the rest of the soundtrack on GarageBand using drum machines and ’80s and ’90s synthesizer sounds he collected for , a project to promote awareness of environmental science through video games.

The slightly jarring soundtrack is a new way to experience the rise in global carbon dioxide. Levels go up and down slightly each year because the Northern Hemisphere has more vegetation than the Southern Hemisphere, and plants take in carbon dioxide during the summer and then release it again in the winter. Accompanying that oscillation is a gradual, constant upward trend.

Twedt had been exploring new ways to present science to the public. With a musical background playing piano and flute, she felt music offered novel possibilities.

“When your eye looks at a curve you see it all at once, but when you hear it, you’re forced to think about the temporal duration,” Twedt said. “There’s something special about sonifying a timeseries where you actually have to wait and listen for each data point to come. That’s what I think is special.”

The video is the latest outreach effort from the UW’s Department of Atmospheric Sciences. Frierson regularly plays the mandolin and sings climate-themed adaptations of pop songs in an undergraduate course he teaches on global warming. Graduate students in the department also create other including, most recently, a series about El Nino’s effects on sardines.

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For more information, contact Frierson at dargan@uw.edu or 206-685-7364 and Twedt at jtwedt@uw.edu.

Audio file:

Two 天美影视传媒 teams claimed top prizes in the fall competition, and both games will be on display Thursday, Jan. 21 for an at the Smithsonian’s National Museum of Natural History in Washington, D.C.

, a video game, won first place in the “college” category. It was designed by , a UW associate professor of atmospheric sciences, , a computer science and engineering doctoral student who is a member of the UW’s Center for Game Science, and , a senior undergraduate in the Information School.

placed third in the “open” category. The board game was designed by , a graduate student in aquatic and fishery sciences, , a graduate student in computer science and engineering, and Seattle-based artist .

Chen and Lee are in D.C. this week for two events at the natural history museum, where the public will have a first chance to play the games.

The two UW entries take very different approaches. Climate Quest is a 5- to 10-minute online video game that has players move cartoon characters to quickly address climate-related disasters around the country. (Frierson composed the accompanying 8-bit soundtrack.) It’s available as a free download for聽 or , and an app is in the works.

AdaptNation is a cooperative board game, in which three to six players each lead a fictional city. Each city faces different challenges as players work together to keep the whole nation afloat as conditions change from 2025 to 2055. It will be out soon.

Both UW entries were done through , a group started in early 2015 by Frierson and , a UW associate professor of environmental and forest sciences. The group began working on student projects that combine climate science and gaming with members of departments across campus, including Computer Science & Engineering, Atmospheric Sciences and other units. Frierson and Lawler have been working with students in the UW’s Information School on senior- and graduate-level projects that involve building a video game.

“I think that interaction really helps for learning,” said Frierson, who grew up playing video games. “Especially for environmental issues, I think this has been an untapped avenue for inspiring and teaching people.”

When the UW group heard about the inaugural Climate Game Jam, it was a no-brainer to enter. The October weekend marathon event attracted a small core group that spent almost all of the second night wrapping up their entries. Sponsors of the contest included the White House’s Office of Science and Technology, the National Oceanic and Atmospheric Administration and the Smithsonian Institution.

Since the prizes were announced, “it’s done a good job in kick-starting interest on campus,” Frierson said.

The UW group meets Mondays afternoons. It’s is open to anyone who has a background in game design, or a willingness to learn. Roughly two dozen current members include UW students and faculty, as well as working professionals in the gaming industry. Lately the group has been perfecting the two games that are debuting this week. Next they will be working on applying for grants, organizing events, and devising more games that incorporate environmental issues 鈥� including two games that feature pikas.

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For more information, contact Frierson at 206-685-7364 or dargan@uw.edu, or聽 EarthGamesUW@gmail.com.听

Scientists long believed that this was a quirk of the Earth’s geometry 鈥� that the ocean basins tilting diagonally while the planet spins pushed tropical rain bands north of the equator. But a new 天美影视传媒 study shows that the pattern arises from ocean currents originating from the poles, thousands of miles away.

The findings, published Oct. 20 in , explain a fundamental feature of the planet’s climate, and show that icy waters affect seasonal rains that are crucial for growing crops in such places as Africa’s Sahel region and southern India.

In general, hotter places are wetter because hot air rises and moisture precipitates out.

“It rains more in the Northern Hemisphere because it’s warmer,” said corresponding author , a UW associate professor of atmospheric sciences. “The question is: What makes the Northern Hemisphere warmer? And we’ve found that it’s the ocean circulation.”

Frierson and his co-authors first used detailed measurements from NASA’s Clouds and Earth’s Radiant Energy System, or , satellites to show that sunlight actually provides more heat to the Southern Hemisphere 鈥� and so, by atmospheric radiation alone, the Southern Hemisphere should be the soggier one.

After using other observations to calculate the ocean heat transport, the authors next used computer models to show the key role of the that sinks near Greenland, travels along the ocean bottom to Antarctica, and then rises and flows north along the surface. Eliminating this current flips the tropical rain bands to the south.

The reason is that as the water moves north over many decades it gradually heats up, carrying some 400 trillion (that’s four with 14 zeroes after it) watts of power across the equator.

For many years, slanting ocean basins have been the accepted reason for the asymmetry in tropical rainfall.

“But at the same time, a lot of people didn’t really believe that explanation because it’s kind of a complicated argument.听 For such a major feature there鈥檚 usually a simpler explanation,” Frierson said.

The ocean current they found to be responsible was made famous in the 2004 movie “The Day After Tomorrow,” in which the premise was that the overturning circulation shut down and New York froze over. While a sudden shutdown like in the movie won’t happen, a gradual slowing 鈥� which the recent United Nations report said was “very likely” by 2100 鈥� could shift tropical rains south, the study suggests, as it probably has in the past.

The slowdown of the currents is predicted because increasing rain and freshwater in the North Atlantic would make the water less dense and less prone to sinking.

“This is really just another part of a big, growing body of evidence that’s come out in the last 10 or 15 years showing how important high latitudes are for other parts of the world,” Frierson said.

Frierson’s earlier work shows how the changing temperature balance between hemispheres influences tropical rainfall. A by Frierson and collaborators looked at how pollution from the industrial revolution blocked sunlight to the Northern Hemisphere in the 1970s and ’80s and shifted tropical rains to the south.

“A lot of the changes in the recent past have been due to air pollution,” Frierson said. “The future will depend on air pollution and global warming, as well as ocean circulation changes. That makes tropical rainfall particularly hard to predict.”

Co-authors are Yen-Ting Hwang, Elizabeth Maroon, Xiaojuan Liu and David Battisti at the UW; Neven Fu膷kar at the University of Hawaii; Richard Seager at Columbia University; Sarah Kang at South Korea’s Ulsan National Institute of Science and Technology; and Aaron Donohoe at the Massachusetts Institute of Technology.

The research was funded by the National Science Foundation, the Japan Agency for Marine-Earth Science and Technology, the National Aeronautic and Space Administration, the National Oceanic and Atmospheric Administration and the U.S. Department of Defense.

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For more information, contact Frierson at 206-685-7364 or dargan@atmos.washington.edu.

The shrinking lake and prolonged drought were initially blamed on overgrazing and bad agricultural practices. More recently, Lake Chad became an example of global warming.

New 天美影视传媒 , to be published in , shows that the drought was caused at least in part by Northern Hemisphere air pollution.

Aerosols emanating from coal-burning factories in the United States and Europe during the 1960s, ’70s and ’80s cooled the entire Northern Hemisphere, shifting tropical rain bands south. Rains no longer reached the Sahel region, a band that spans the African continent just below the Sahara desert.

When clean-air legislation passed in the U.S. and Europe, the rain band shifted back, and the drought lessened.

by the UW researchers and their collaborators shows that global warming is now causing the land-covered Northern Hemisphere to warm faster than the Southern Hemisphere, further reversing the pre-1980s trend.

Previous research has suggested a connection between coal-burning and the Sahel drought, but this was the first study that used decades of historical observations to find that this drought was part of a global shift in tropical rainfall, and then used multiple climate models to determine why.

“One of our research strategies is to zoom out,” said lead author , a UW doctoral student in atmospheric sciences. “Instead of studying rainfall at a particular place, we try to look for the larger-scale patterns.”

To determine that the Sahel drought was part of a broader shift, the authors looked at precipitation from all rain gauges that had continuous readings between 1930 and 1990.听 Other places on the northern edge of the tropical rain band, including northern India and South America, also experienced drier climates in the 1970s and ’80s. Meanwhile, places on the southern edge of the rain band, such as northeast Brazil and the African Great Lakes, were wetter than normal.

To understand the reason, authors looked at all 26 climate models used by the . Researchers discovered that almost all the models also showed some southward shift, and that cooling from sulfate aerosols in the Northern Hemisphere was the primary cause.

“We think people should know that these particles not only pollute air locally, but they also have these remote climate effects,” Hwang said.

Light-colored sulfate aerosols are emitted mainly by dirty burning of coal. They create hazy air that reflects sunlight, and also lead to more reflective, longer-lasting clouds.

People living in the Northern Hemisphere did not notice the cooling, the authors said, because it balanced the heating associated with the greenhouse effect from increased carbon dioxide, so temperatures were steady.

“To some extent, science messed this one up the first time around,” said co-author , a UW associate professor of atmospheric sciences. “People thought that a large part of that drought was due to bad farming practices and desertification. But over the last 20 years or so we’ve realized that that was quite wrong, and that large-scale ocean and atmosphere patterns are significantly more powerful in terms of shaping where the rains fall.”

The models did not show as strong a shift as the observations, Frierson said, suggesting that ocean circulation also played a role in the drought.

The good news is that the U.S. Clean Air Act and its European counterpart had an unintended positive effect beyond improved air quality and related health benefits. Although shorter-term droughts continue to affect the Sahel, the long-term drought began to recover in the 1980s.

“We were able to do something that was good for us, and it also benefited people elsewhere,” Frierson said.

The work was funded by the National Science Foundation. at the Ulsan National Institute of Science and Technology in South Korea was a co-author.

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For more information, contact Hwang at 206-543-0333 or yting@atmos.washington.edu and Frierson at 206-685-7364 or dargan@atmos.washington.edu.

It turns out that in sultry weather condensation on the outside of a canned beverage doesn’t just make it slippery: those drops can provide more heat than the surrounding air, meaning your drink would warm more than twice as much in humid weather compared to in dry heat. In typical summer weather in New Orleans, heat released by condensation warms the drink by 6 degrees Fahrenheit in five minutes.

“Probably the most important thing a does is not simply insulate the can, but keep condensation from forming on the outside of it,” said , a UW professor of atmospheric sciences.

He’s co-author of results published in the April issue of that give the exact warming for a range of plausible summer temperatures and humidity levels. For example, on the hottest, most humid day in Dhahran, Saudi Arabia, condensation alone would warm a can from near-freezing temperature to 48 degrees Fahrenheit in just five minutes.

The investigation began a couple of years ago when Durran was teaching UW Atmospheric Sciences 101 and trying to come up with a good example for the heat generated by condensation. Plenty of examples exist for evaporative cooling, but few for the reverse phenomenon. Durran thought droplets that form on a cold canned beverage might be just the example he was looking for.

A quick back-of-the-napkin calculation showed the heat released by water just four thousandths of an inch thick covering the can would heat its contents by 9 degrees Fahrenheit.

“I was surprised to think that such a tiny film of water could cause that much warming,” Durran said.

Though he’s normally more of a theoretician, Durran decided this result required experimental validation. He recruited co-author , a UW associate professor of atmospheric sciences, and they ran an initial test in Frierson’s little-used basement bathroom, using a space heater and hot shower to vary the temperature and humidity.

The findings corroborated the initial result, and they embarked on a larger-scale test.

“You can’t write an article for Physics Today where the data has come from a setup on the top of the toilet tank in one of the author’s bathrooms,” Durran said.

First they recruited colleagues in Frierson’s beachside hometown of Wilmington, North Carolina, to duplicate the experiment and compare results with those taken on a hot, dry Seattle day. But they decided they needed to test a wider range of conditions.

Finally, last summer undergraduates Stella Choi and Steven Brey joined the project to run a proper experiment in the UW Atmospheric Sciences building. They unearthed an experimental machine with styling that looks to be from the 1950s, last used decades ago to simulate cloud formation.

With funding for educational outreach from the National Science Foundation, the students first cooled a can in a bucket of ice water then dried it and placed it in the experimental chamber dialed up to the appropriate conditions. After five minutes they removed the can, weighed it to measure the amount of condensation, and recorded the final temperature of the water inside.

The phenomenon at work 鈥� latent heat of condensation 鈥� is central to Frierson’s research on water vapor, heat transfer and global climate change.

“We expect a much moister atmosphere with global warming because warmer air can hold a lot more water vapor,” Frierson said. Because heat is transferred when water evaporates or condenses, this change affects wind circulation, weather patterns and storm formation.

Durran’s research includes studies of thunderstorms, which are powered by heat released from condensation in rising moist air.

As for his demonstration of the heat released during this process, he and Frierson are now working with the National Center for Atmospheric Research to develop an educational tool that will let students around the world try the experiment and post their results online for comparison.

The example promises to become as classic as a cold drink on a hot summer day.

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For more information, contact Durran at 206-543-7440 or durrand@atmos.washington.edu and Frierson at 206-685-7364 or dargan@atmos.washington.edu.

天美影视传媒 atmospheric scientists hope their results help explain why global climate models mistakenly duplicate the inter-tropical convergence zone, a band of heavy rainfall in the northern tropics, on the other side of the equator. The appears this week in the .

“There have been tons of efforts to get the tropical precipitation right, but they have looked in the tropics only,” said lead author , a UW doctoral student in atmospheric sciences. She found the culprit in one of the most remote areas of the planet.

“What we found, and that was surprising to us, is the models tend to be not cloudy enough in the Southern Ocean so too much sunlight reaches the ocean surface and it gets too hot there,” Hwang said. “People think of clouds locally, but we found that these changes spread into the lower latitudes.”

Previous studies looking at the problem investigated tropical sea-surface temperatures, or ways to better represent tropical winds and clouds. But none managed to correctly simulate rainfall in the tropics 鈥� an important region for global climate predictions, since small shifts in rainfall patterns can have huge effects on climate and agriculture.

“The rain bands are very sharp in this area,” commented co-author , a UW associate professor of atmospheric sciences. “You go from some of the rainiest places on Earth to some of the driest in just a few hundred kilometers.”

Recent theories suggest tropical rainfall might be linked to global processes. Hwang’s research, funded by the National Science Foundation, looked for possible connections to ocean temperatures, air temperatures, winds and cloud cover.

“For the longest time we were expecting that it would be a combination of different factors,” Frierson said, “but this one just stood out.”

The paper shows that cloud biases over the Southern Ocean are the primary contributor to the double-rain band problem that exists in most modern climate models.

“It almost correlates perfectly,” Hwang said. “The models that are doing better in tropical rainfall are the ones that have more cloud cover in the Southern Ocean.”

Hwang will speak on her results in April to scientists at the . The results have also been submitted for inclusion in the fifth report of the , which is expected to appear next year.

Most models don’t generate enough low-level clouds over the perpetually stormy Southern Ocean, the authors found, so heat accumulates in the Southern Hemisphere.

“Basically hot air rises, and it rains where air rises. So it’s kind of obvious that the rain is going to be over warmer ocean temperatures,” Frierson said. “Our new thinking is that the heat spreads 鈥� it’s the warmth of the entire hemisphere that affects tropical rainfall.”

In the short term, climate scientists can look for ways to improve the models to increase cloud cover over the Southern Ocean. Eventually, more powerful computers may permit models that are able to accurately simulate clouds over the entire planet.

“We have confidence in climate predictions outside the tropics, but tropical rainfall forecasts are much less certain,” Frierson said. “We hope this work will lead to better rainfall forecasts in regions like equatorial Africa, where it’s so important to have accurate predictions of future patterns.”

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For more information, contact Hwang at 206-543-0333 or yting@atmos.washington.edu and Frierson at 206-685-7364 or dargan@atmos.washington.edu. Ting is traveling until March 17 and is best reached via e-mail.