Climate change has long been expected to disrupt future fire patterns across the globe, and a new analysis of 16 climate models has only confirmed what many scientists had long feared.
The study, led by researchers at the University of California, Berkeley and in collaboration with an international team of scientists, found that by the end of this century almost all of North America and most of Europe is projected to see a jump in the frequency of wildfires, primarily as a result of increasing temperature trends.
Ironically, fire activity could drop in equatorial regions, particularly throughout tropical rainforests, as a result of an increase in rainfall.
Confirmation of Worst Fears
The study was published on the 12th of June in the journal Ecosphere and was based on 16 different climate change models, together generating what the researchers labeled one of the most comprehensive projections to date of how climate change may affect global fire patterns.
“In the long run, we found what most fear — increasing fire activity across large parts of the planet,” said study lead author Max Moritz, fire specialist in UC Cooperative Extension. “But the speed and extent to which some of these changes may happen is surprising.”
“These abrupt changes in fire patterns not only affect people’s livelihoods,” Moritz added, “but they add stress to native plants and animals that are already struggling to adapt to habitat loss.”
Comprehensive and Robust Modelling
The researchers combined over a decade of satellite-based fire records with historical climate observations and model simulations of future change. They documented gradients between fire-prone and fire-free areas of the planet, and quantified the environmental factors believed to be at the heart of these patterns. They then used these relationships to determine how future climate change may end up driving future fire activity throughout the coming decades.
“Most of the previous wildfire projection studies focused on specific regions of the world, or relied upon only a handful of climate models,” said study co-author Katharine Hayhoe, associate professor and director of the Climate Science Center at Texas Tech University. “Our study is unique in that we build a forecast for fire based upon consistent projections across 16 different climate models combined with satellite data, which gives a global perspective on recent fire patterns and their relationship to climate.”
The fire models in this study are based on climate averages that include mean annual precipitation and mean temperature of the warmest month. These variables tend to control long-term biomass productivity and how flammable that fuel can get during the fire season, the researchers said.
Variables that reflect more ephemeral fluctuations in climate, such as annual rainfall shifts due to El Niño cycles, were not included because they vary over shorter periods of time, and future climate projections are only considered representative for averages over time periods of 20-30 years or longer, the authors said.
Near-term Uncertainty, Long-term Certainty
The analysis found that the greatest disagreements between models and data occurred over the next few decades. Currently, the data does not agree as to whether fire activity will increase or decrease for more than half the planet.
On the other hand, some areas of the world — such as the western United States — show a high level of agreement in climate models — both near- and long-term — resulting in a strong consensus that those regions should start to expect more fire.
Experts in conservation and urban development will do well to look closely at these consensus-projections as they determine long-term planning and risk analysis, added Moritz.
“When many different models paint the same picture, that gives us confidence that the results of our study reflect a robust fire frequency projection for that region,” said Hayhoe. “What is clear is that the choices we are making as a society right now and in the next few decades will determine what Earth’s climate will look like over this century and beyond.”
“We need to learn how to coexist with fire,” said Moritz.
Study co-author David Ganz, who was director of forest carbon science at The Nature Conservancy at the time of the study, noted the significance of the findings for populations that rely upon fire-sensitive ecosystems.
“In Southeast Asia alone, there are millions of people that depend on forested ecosystems for their livelihoods,” he said. “Knowing how climate and fire interact are important factors that one needs to consider when managing landscapes to maintain these ecosystem goods and services.”