Even if you live far from the boreal forests in Canada and Siberia, you’ve 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 — 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 91̽��-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.

“This 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,” said lead author , a 91̽��research associate professor of atmospheric and climate science. “It’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’t say this is good news. But it helps us better understand nature and these trends.”

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.

“If 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,” Blanchard-Wrigglesworth said. “Those are the big years of Siberian fires. And then 2023 was the even bigger Canadian fire season.”

Because climate scientists don’t 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’ 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.

“I 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,” Blanchard-Wrigglesworth said. “If 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.”

, of Université Catholique de Louvain, and , a 91̽��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.

Amid all the changes in Earth’s climate, sea ice in the stormy Southern Ocean surrounding Antarctica was, for a long time, an odd exception. The maximum winter sea ice cover remained steady or even increased slightly from the late 1970s through 2015, despite rising global temperatures.

That began to change in 2016. Several years of decline led to , more than five standard deviations below the average from the satellite record. The area of sea ice was 2.2 million square kilometers below the average from the satellite record, a loss almost 12 times the size of Washington state. The most recent winter’s peak, recorded in September 2024, was to the previous year’s record low.

91̽�� researchers show that the all-time record low can be explained by warm Southern Ocean conditions and patterns in the winds that circled Antarctica months earlier, allowing forecasts for sea ice coverage around the South Pole to be generated six or more months in advance. This could support regional and global weather and climate models.

The open-access was published Nov. 20 in Nature Communications Earth & Environment.

“Since 2015, total Antarctic sea ice area has dramatically declined,” said lead author , a 91̽��doctoral student in atmospheric and climate science. “State-of-the-art forecasting methods for sea ice generally struggle to produce reliable forecasts at such long leads. We show that winter Antarctic sea ice has significant predictability at six- to nine-month lead times.”

The authors used a global climate model to simulate how ocean and air temperatures, including longer-term cycles like El Niño and La Niña, affect sea ice in the Southern Ocean.

Results showed that the 2023 El Niño was less important than previously thought. Instead, an arching pattern of regional winds, and their effects on ocean temperatures up to six months in advance, could explain 70% of the 2023 record-low winter sea ice. These winds cause ocean mixing in the Southern Ocean that can pull deeper warm water up to the surface, thus suppressing sea ice growth. Winds can also push sea ice poleward toward Antarctica to prevent the sea ice edge from expanding north, transport heat from lower latitudes toward the poles, and generate ocean waves that break up sea ice.

Using the same approach for the 2024 observations correctly predicted that this would be another low year for Southern Ocean sea ice cover.

“It’s interesting that, despite how unusual the winter sea ice conditions were in 2023 and again in 2024, our results show they were remarkably predictable over 6 months in advance,” said co-author , a 91̽��research associate professor of atmospheric and climate science.

Antarctic sea ice is important because it affects marine and coastal ecosystems and interactions between ocean and atmosphere in the Southern Ocean. It also affects global climate by reflecting sunlight in the Southern Hemisphere and influencing ice sheets and global currents.

“Antarctic sea ice is a major control on the rate of global warming and the stability of ice on the Antarctic continent,” Espinosa said. “In fact, the sea ice acts to buttress ice shelves, increasing their stability and slowing the rate of global sea level rise. This ice is also important for marine and coastal ecosystems.”

As summer arrives in the Southern Hemisphere, the remains sparse around Antarctica, close to a record low for this time of the year.

“Our success at predicting these major sea ice loss events so far in advance demonstrates our understanding of the mechanism that caused them,” said co-author , a 91̽��professor of atmospheric and climate science. “Our model and methods are geared up to predict future sea ice loss events.”

The research was funded by the National Science Foundation and the U.S. Department of Energy.

For more information, contact Espinosa at zespinosa97@gmail.com, Bitz at bitz@uw.edu and Blanchard-Wrigglesworth at edwardbw@uw.edu.

A warming climate is causing a decline in sea ice in the Arctic Ocean, where loss of sea ice has important ecological, economic and climate impacts. On top of this long-term shift due to climate change are weather events that affect the sea ice from week to week.

The strongest Arctic cyclone ever observed poleward of 70 degrees north latitude struck in January 2022 northeast of Greenland. A new analysis led by the 91̽�� shows that while weather forecasts accurately predicted the storm, ice models seriously underestimated its impact on the region’s sea ice.

The , published in October in the Journal of Geophysical Research–Atmospheres, suggests that existing models underestimate the impact of big waves on ice floes in the Arctic Ocean.

“The loss of sea ice in six days was the biggest change we could find in the historical observations since 1979, and the area of ice lost was 30% greater than the previous record,” said lead author , a research assistant professor of atmospheric sciences at the UW. “The ice models did predict some loss, but only about half of what we saw in the real world.”

Accurate sea ice forecasts are important safety tools for Northern communities, mariners and others operating in Arctic waters. The accuracy of forecasts in the Arctic Ocean also has broader effects.

“The skill of a weather forecast in the Arctic affects the skill of weather forecasts in other places,” Blanchard-Wrigglesworth said.

The January 2022 cyclone had the lowest pressure center estimated since satellite records began in 1979 above 70 degrees north. It was an extreme version of a typical winter storm. Climate change doesn’t appear responsible for the cyclone: The researchers didn’t find a trend in the strength of intense Arctic cyclones since 1979, and sea ice area was close to the historical normal for that region before the storm hit.

Waves travel through sea ice in the Arctic Ocean, as seen from a ship in October 2015. Credit: Ed Blanchard-Wrigglesworth/91̽��

During the storm, record winds howled over the Arctic Ocean. The waves grew to 8 meters (26 feet) tall in open water and remained surprisingly strong as they traveled through the sea ice. The ice heaved 2 meters (6 feet) up and down near the edge of the pack, and NASA’s ICESat-2 satellite shows that the waves reached as far as 100 kilometers (60 miles) toward the center of the ice pack.

Six days after the storm struck, the sea ice had thinned significantly in the affected waters north of Norway and Russia, in places losing more than half a meter (about 1.5 feet) of thickness.

“It was a monster storm, and the sea ice got pummeled. And the sea ice models didn’t predict that loss, which suggests there are ways we could improve the model physics,” said second author , a research assistant professor at the University of Alaska Fairbanks. She begins a research position at the 91̽��Applied Physics Laboratory in the new year.

The new analysis shows that the atmospheric heat from the storm had a small effect, meaning some other mechanism was to blame for the ice loss. Possibilities, Blanchard-Wrigglesworth suggests, include sea ice that was thinner before the storm hit than models had estimated; that the storm’s waves broke up ice floes more forcefully than models predicted as they penetrated deep into the ice pack; or that waves churned up deeper, warmer water and brought it into contact with the sea ice, melting the ice from below.

The unexpected ice loss, despite an accurate storm forecast, suggests that this is an area where models could improve. The researchers hope to monitor future storms to pinpoint exactly what led to the dramatic sea ice loss, potentially by placing sensors in the path of a future approaching storm.

While this storm doesn’t appear to be linked to climate change, the increase of open water as sea ice melts is allowing for larger waves that are eroding Arctic coastlines. Those waves, researchers said, could also affect the remaining sea ice pack.

“Going into the future, this is something to keep in mind, that these extreme events might produce these episodes of huge sea ice loss,” Blanchard-Wrigglesworth said.

Other co-authors are at NASA, at NASA and the University of Maryland and at the University of Auckland and Brown University. The research was funded by NASA, the U.S. Navy’s Office of Naval Research and Schmidt Futures.

For more information, contact Blanchard-Wrigglesworth at ed@atmos.uw.edu or Webster at mwebster3@alaska.edu.

Grants: NASA: 80NSSC20K0922, 80NSSC20K0959, ONR-DRI: N00014-21-1-2490

is a 91̽��-wide institute connecting scholars with community partners to address environmental challenges. The institute announced awards for its 2020 on May 5.

Four research teams were chosen from 43 that applied. Proposals were reviewed by an 11-member committee including faculty and staff in several areas as well as an outside community member. This is the program’s second year.

Each team will receive up to $75,000 as well as administrative and communications support for a 16-month period ending in September 2021.

Crucially, the researchers also plan to collaborate with community partners from El Centro de la Raza locally to universities internationally for these projects. All of the community partners involved are listed on the .

Does vegetation help mitigate roadway and aircraft-related air pollution in Seattle?

, associate professor of environmental and occupational health sciences, is principal investigator on this community-engaged study using drones for 3D air quality measurements.

Co-investigators are professor and assistant professor of civil and environmental engineering, and , professor of atmospheric sciences.

According to their proposal, “Findings from this study will provide local and highly relevant evidence on the effectiveness of urban planning initiatives that may utilize greenery as an approach to address particulate air pollution.”

Hazard planning, food sovereignty and climate adaptation in the Alaskan Arctic��

, assistant professor in the Department of American Indian Studies and the School of Marine and Environmental Affairs, is this project’s principal investigator and co-director.

is a 500-person community in Northwest Alaska about 80 miles above the Arctic Circle. Sea-ice cover around this area has decreased dramatically in the last two decades, increasing coastal erosion during storms and the frequency of traveler distress calls, among other concerns.

For this research, an interdisciplinary team of 91̽��polar researchers will work with area search and rescue volunteers to help Kivalina and its residents achieve more safety, resilience and food sovereignty, and become a model of community-driven polar research. The team also plans to develop new methods in sea ice forecasting to support local decision-making, among several other goals.

Other 91̽��researchers involved are , chair and professor; and , research assistant professor, both in atmospheric sciences.

Píkyav on the Mid-Klamath River: Peeshkêesh Yáv Umúsaheesh

The flows through parts of Oregon and Northern California. Four hydroelectric dams along the river are scheduled for removal in 2022. The , in that area, is among the largest in California.

This research team proposes a river restoration process on the Klamath that centers on Karuk tribal sovereignty using a model of justice, helping to bring tribal perspectives to large-scale governance. The title of the project, they write, translates to “the river will look good” — and the phrase “goes far below the surface to include function, connection and ceremonial renewal.”

The team plans an intergenerational, field-based school on the river, working with Karuk youth and cultural practitioners to gather historical maps, stories and spatial data on Karuk uses of floodplain ecosystems.

91̽��team members for this project are , assistant professor in the School of Marine and Environmental Affairs; , a lecturer in Comparative History of Ideas and the Program on the Environment; and Karuk tribal member Kimberly Yazzie, a doctoral student in the School of Aquatic and Fishery Sciences.

Lessons from urban indigenous immigrants ��

“This project will compare a self-managed indigenous immigrant community still using traditional practices in Iquitos, Peru,” the team wrote, “to a similar indigenous immigrant community nearby that developed with social and political pressures to colonially urbanize and leave traditional practices behind.”

91̽��members of the research team are , affiliate assistant professor of landscape architecture; , photographer with the 91̽��Center for One Health Research; , lecturer in the 91̽��Bothell School of Interdisciplinary Arts & Sciences; Kathleen Wolf, research social scientist with the School of Environment and Forest Sciences; and doctoral student of the School of Public Health.

“We use an innovative, mixed-methods approach by combining indigenous knowledge, science and art to document environmental conditions, ecosystem health, traditional knowledge practices, and human-nature connections in each community,” the team wrote.

Environmental and human health impacts of a new invasive species in Madagascar

A fifth project was in March, representing the second project funded in collaboration with the 91̽��Population Health Initiative. The project’s 91̽��leads are , assistant professor in the School of Aquatic and Fishery Sciences; and , professor in the Department of Environmental and Occupational Health Sciences.

For more information, contact the EarthLab Innovation Grants program lead at elgrants@uw.edu.

91̽�� polar scientists are on Alaska’s North Slope this week for the 2016 Barrow Sea Ice Camp. Supported by the National Science Foundation, the event brings together U.S.-based sea ice observers, satellite experts and modelers at various career stages to collect data and discuss issues related to measuring and modeling sea ice. The goal is to integrate the research community in order to better observe and understand the changes in Arctic sea ice.

Check out the group’s , written by a who’s taking his first trip into the field, or follow updates on . The group is based just north of Barrow from May 26 to June 2, in the northernmost point in the U.S.

91̽��participants include , a 91̽��professor of atmospheric sciences, , an oceanographer at the 91̽��Applied Physics Laboratory, , a physicist at the Applied Physics Laboratory, , a 91̽��graduate who is now a research assistant at APL, 91̽��atmospheric sciences postdoctoral researchers and , and , an anthropology student who has a visiting appointment at APL.

Current conditions form an important starting point that governs how the ice responds to weather in the course of a few years, 91̽��-led research shows. But eventually climate trends overtake that starting point as the primary influence on the overall predictability of sea ice conditions.

“The Arctic is one of the places where conditions are changing the fastest of any climate system in the world,” said Edward Blanchard-Wrigglesworth, a 91̽��doctoral student in atmospheric sciences. “Current trends are so strong that it takes five years to establish a new mean.”

Blanchard-Wrigglesworth is lead author of a published Wednesday (Sept. 21) in . Co-authors are Cecilia Bitz, a 91̽��atmospheric sciences professor, and Marika Holland of the in Colorado.

Research from the indicates the low point of this summers Arctic sea ice cover was 36 percent less than the average minimum from 1979 through 2000, and was just a fraction above the record low in 2007.

In the new study, the scientists used the Community Climate System Model version 4, one of only a few models that have successfully simulated the rate of Arctic sea ice decline that has occurred so far.

They found that measurements of ice thickness and area in September could provide a good gauge for what the ice expanse would be like at its low ebb the following summer, July through September.

Such predictions are important for shipping – knowing whether the Northeast and Northwest passages might be ice-free in summer, for example – or for natural resource interests such as oil exploration. They also are important for native populations who depend on the sea ice for their livelihoods and to conservationists trying to preserve species such as polar bears.

Measuring the area of Arctic sea ice is relatively simple for satellites, Blanchard-Wrigglesworth said, but determining the thickness – and thus the volume – is much trickier and something for which satellites have only produced reasonable estimates in the last 10 years or so.

“The key thing about assessing the model is comparing the models trend and variability to real-world conditions,” he said. “With a successful comparison, we believe the predictive results we see in the model are relevant to the real world.”

Since the current sea ice conditions are instrumental in forecasting conditions only a few years in the future, they dont tell scientists what lies in store for the icepack at the top of the world in the coming decades. Many scientists believe the Arctic could be completely free of sea ice in summer by the middle of this century.

Based on the models results using projections for increases in atmospheric greenhouse gases such as carbon dioxide, Blanchard-Wrigglesworth agrees.

“Its reasonable to think the planet will follow the model fairly closely if the forcing conditions evolve as they are predicted to,” he said.

The work was funded by the , and computing support was provided by the National Center for Atmospheric Research.

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For more information, contact Blanchard-Wrigglesworth at ed@atmos.washington.edu.