Accessing the influence of human activities on wildfires

In a first-of-its-kind study, scientists have assessed the influence of human activities on extreme fire weather risk, and found that greenhouse gas emissions and air pollution have distinct regional impacts on wildfire outbreaks.

The research, published in the journal Nature Communications, analysed the climate under various combinations of human influences since 1920, isolating individual effects and their impacts on extreme fire weather risk.

While previous studies found that human activities and their products like greenhouse gas emissions, and air pollution raise the risk of extreme fire weather, the scientists, including those from the University of Califor nia (UC) Santa Barbara in the US, said the specific influence of these factors has been unclear.

"To get a wildfire to ignite and spread, you need suitable weather conditions — you need warm, dry and windy conditions," explained Danielle Touma, a co-author of the study from UC Santa Barbara. "And when these conditions are at their most extreme, they can cause really large, severe fires," Touma said.

According to the researchers, heat-trapping greenhouse gas emissions are the dominant contributors to temperature increases around the globe. By 2005, they said emissions raised the risk of extreme fire weather by 20 per cent from preindustrial levels in western and eastern North America, the Mediterranean, Southeast Asia, and the Amazon.

However, in Southeast Asia, "where aerosols emissions are expected to continue," the study said there may be a weakening of the annual monsoon, drier conditions and an increase in extreme fire weather risk.

"Southeast Asia relies on the monsoon, but aerosols cause so much cooling on land that it actually can suppress a monsoon," Touma said. —PTI