The study was conducted by an international team of researchers, including fire experts Sander Veraverbeke and Guido van der Werf from VU Amsterdam, and led by the University of East Anglia (UK). They examined climate datasets, satellite data and climate models and reviewed the results of more than 500 previous research papers to investigate the relationship between increases and decreases in wildfires and various factors that influence them, such as climate, vegetation and land use. All findings were published in the journal Reviews of Geophysics.
An unprecedented increase in fire weather
Fire weather – the hot, dry conditions conducive to wildfires - is increasing under climate change, raising the risk of large wildfires by making landscapes more susceptible to burn more often and more severely. Climate models suggest that, in some world regions, for example the Mediterranean and Amazonia, the frequency of current severe fire weather is unprecedented compared with recent historic climate, due to human-induced global warming of around 1.2°C. More importantly, this will be the case in almost all world regions if global temperatures reach 2-3°C of warming as per the current trajectory.
People have a lot of influence on wildfires
Cutting our greenhouse gas emissions and limiting warming to below 2°C is the most effective thing we can do to avoid the risk of forest fires. Guido van der Werf, professor in the global carbon cycle and land use change at VU Amsterdam: “In addition to the climate effect, people affect wildfires in other ways. For example, there has been a decrease in wildfires in some places. This is mainly because savanna ecosystems that burn frequently are being converted to agricultural land, thereby fragmenting the natural landscape. However, this dynamic is limited to areas where mainly grasslands are burning and is contrary to the increases we see in many woodlands.”
Explanations for regional differences
The research provides insight into how various factors that influence wildfires, such as climate, but also fragmentation of landscapes, are regionally different. Sander Veraverbeke, associate professor in climate and ecosystems change at VU Amsterdam: “A milestone achievement of this mega review is that it provides explanations for the important regional differences in fire trends under climate change. Forests in the mid and high latitudes are particularly sensitive to increasing fire extent and severity under climate change. In other regions, the elevated climatic risk for increasing fire is also present, however, fire activity is often heavily influenced by human activity controlling fire ignitions and spread. This also shows that there are opportunities to mitigate the negative effects of fires by thoughtfully managing ecosystems and landscapes.”