Researchers from the University of Colorado Boulder and the National Center for Atmospheric Research (NCAR) discovered that soot and other burned biomass from wildfires in Colorado and other parts of the Northern Hemisphere can eventually travel to the Arctic by examining the differences between climate models. Once there, it can have an impact on how much sea ice is present at any given time.
This can then have an impact on global climate patterns, creating a feedback loop connecting the two systems in a way that hasn’t been witnessed before.
The principal author of the study and a postdoctoral scholar at NCAR, Patricia DeRepentigny (PhDAtmos’21), stated that the study “discovered that particles produced from wildfires where people live may profoundly effect what occurs in the Arctic hundreds of kilometres away.”
“The Arctic is sometimes perceived as a place we shouldn’t worry about since it is so far from where we live. However, the fact that there is a back-and-forth relationship between what occurs here with wildfires and the sea ice, and that a declining sea ice might subsequently cause more wildfires here, strengthens our connection to the Arctic.”
Governments all across the globe have long utilized climate models, which are simulations of how various elements of the climate interact, to help direct future climate change policy. These models have gotten more sophisticated and capable as science has progressed.
DeRepentigny and colleagues discovered, however, that a newer model, the NCAR-based Community Earth System Model version 2 (CESM2), showed a sharp acceleration in Arctic sea ice loss at the end of the 20th century that was not seen in the earlier models. So they made the decision to learn the reason.
When forcings (the various ways a climate model can be influenced, such as carbon dioxide or methane emissions or solar radiation) were compared between the new and previous generation of climate models, they discovered that emissions from biomass burning had the greatest impact on simulated Arctic sea ice loss.
They discovered that the major reason these emissions from biomass burning mattered so much was because of the non-linear cloud impacts that may occur when aerosols, which are tiny particles or liquid droplets emitted by fires, mix with Arctic clouds. When there are many aerosols released during a year with a lot of fires, it can result in more and thicker clouds, whereas on years with fewer fires, the clouds are thinner, allowing more solar radiation to pass through and melt more ice.
Large flames spread more widely over the western United States as the sea ice melts, according to earlier studies. This new research implies that this unpredictability may be producing more of a feedback loop than previously believed by demonstrating that smoke from wildfires can aid in protecting the ice.
As an associate professor of atmospheric and oceanic sciences at the Institute of Arctic and Alpine Research (INSTAAR) at the University of Colorado Boulder, Alexandra Jahn, one of the paper’s authors, said, “When we think about climate, everything’s really interconnected, and this is really a great example of that.”
“When considering climate dynamics, we must keep in mind that this is a global issue that cannot be studied in isolation. To truly grasp all of these many relationships, we must constantly consider the whole picture.”
The researchers note out that their research was model-specific—that is, it only examined one particular climate model—but that their trials serve as an excellent foundation for further investigation. This could involve focusing on the effects of particular fires rather than all fires, and fine-tuning the models to perform simulations where the model can produce the fires; for example, if a dry year is predicted, the model could then simulate more fires, which would then affect the predictions for future sea ice loss.
According to DeRepentigny, this study “helps us move closer to something that can actually help us make the greatest decisions as a society,” adding that the objective is to have these climate simulations be more trustworthy and provide forecasts that may then guide policy makers and societal decisions.
Materials provided by University of Colorado at Boulder.