麻豆影院

New CU 麻豆影院 research finds that the presence of clouds鈥攐r lack thereof鈥攃aused by the smoke of wildfires thousands of miles away can either help protect or endanger Arctic sea ice

Sea ice and wildfires may be more interconnected than previously thought, according to new research out today in Science Advances.

By digging into differences between climate models, researchers from the 麻豆影院 and the National Center for Atmospheric Research (NCAR) found that soot and other burned biomass from wildfires here in Colorado and elsewhere in the Northern Hemisphere can eventually make their way to the Arctic. Once there, it can affect how much鈥攐r how little鈥攕ea ice persists at any given time.

This, in turn, can cause ripple effects on climatic patterns for the rest of the globe, reinforcing a feedback loop between the two systems in a way that hasn鈥檛 been previously seen.

鈥淭his research found that particles emitted from wildfires where people live can really impact what happens in the Arctic thousands of miles away,鈥� said Patricia DeRepentigny (PhDAtmos鈥�21), the lead author on the paper and a postdoctoral fellow at NCAR.

鈥淪ometimes the Arctic can be seen as this region that we shouldn鈥檛 care about because it鈥檚 so far away from where we live 鈥� but the fact that there鈥檚 this back-and-forth of what happens here with the wildfires can affect the sea ice, and a diminishing sea ice can then lead to more wildfires here, connects us with the Arctic a little bit more.鈥�

, which are simulations of how different parts of the climate interact, have long been used by governments around the world to help guide future policies related to climate change. As science has become more advanced, so too have these models, gaining sophistication and capability.

However, while completing her PhD in atmospheric and oceanic sciences at CU 麻豆影院, DeRepentigny and her advisor, Alexandra Jahn, noticed that in a recent model, the NCAR-based Community Earth System Model version 2 (CESM2), there was a drastic acceleration of Arctic sea ice loss towards the end of the 20th century that wasn鈥檛 seen in the previous models. So they decided to understand why.

What they found when comparing the forcings (the different ways a climate model can be influenced, such as carbon dioxide or methane emissions or solar radiation) between the new and previous generation of climate models was that biomass burning emissions had the biggest effect on Arctic sea ice loss when simulated.

When they dug deeper into why these biomass burning emissions mattered so much, they found that the main difference is due to the non-linear cloud effects that can emerge when aerosols, small particles or liquid droplets, released by fires interact with Arctic clouds. When there are a lot of aerosols released during a heavy fire year, it can lead to more and thicker clouds, whereas those clouds are thinner on lighter fire years鈥攁llowing for more solar radiation to get through and melt more ice.

Previous research had already shown that when the sea ice melts, large wildfires become more widespread over the western U.S. By showing that smoke from wildfires can help protect the ice, this new research suggests that this variability may be creating more of a feedback loop than previously thought.

鈥淲hen we think about climate, everything鈥檚 really interconnected, and this is really a great example of that,鈥� said Jahn, an author on this paper and an associate professor in atmospheric and oceanic sciences and the Institute of Arctic and Alpine Research (INSTAAR) at CU 麻豆影院.

鈥淲hen we鈥檙e thinking about climate processes, it鈥檚 really a global problem, and we can鈥檛 study it in any isolated fashion. We really always have to look at the global picture to understand all these different interactions.鈥�

The researchers caution that this research was model-specific, which means that it only looked at one specific climate model, but that their experiments provide a great starting point for future research. This includes potentially pinpointing the effects of specific fires, rather than fires broadly speaking, and fine-tuning the models so that they can do simulations where the model itself can generate the fires; thus, if there鈥檚 predicted to be a dry year, the model could then simulate more fires, which in turn would factor into the projections for future sea ice loss.

鈥淭he goal that we鈥檙e trying to achieve here is to have these climate simulations be more reliable and give us projections that can then inform policy makers and societal choices,鈥� DeRepentigny said, adding that this study 鈥渉elps us get closer to something that can truly help us make the best decisions as a society.鈥�

Other authors on the paper include Marika M. Holland, John Fasullo, Jean-Fran莽ois Lamarque, C茅cile Hannay, David A. Bailey, Simone Tilmes and Michael J. Mills at the National Center for Atmospheric Research and Jennifer E. Kay and Andrew P. Barrett at CU 麻豆影院.

Funding for this research was provided by NCAR; the National Science Foundation; Natural Sciences and Engineering Council of Canada; The Fonds de recherche du Que麓bec 鈥� Nature et Technologies; and NASA.