Often times when we talk about climate change, the stories center on melting ice, rising sea levels, and hazards such as hurricanes, droughts, fires and floods. But what about the future of lightning in a warming climate? This summer in Colorado has seen some pretty spectacular electrical storms (see the video below). Research scientists have been working on understanding the relationship between temperature and lightning storms, by estimating the heat energy available to “fuel” storm clouds. As the planet warms there is more “fuel” around, so when thunderstorms get triggered, they will be more energetic. In fact, just one degree Celsius can potentially increase the frequency of lightning strikes by 12% (link to paper in comments). Why should we care? Lightning can trigger wildfires. In fact, according to the US Forest Service, more than 40% of wildfires in the western US (largely in places other than California), were caused by lightning. From 1992 – 2015, those fires accounted for more than 70% of the acreage burned. Increasing drought conditions in the southwestern and western US will only exacerbate the problem.
Interestingly, each lightning strike produces powerful electrical discharges which spark chemical reactions to make greenhouse gases called nitrogen oxides (NOx). NOx can react with sunlight and other gases in the atmosphere to produce ozone. While you may know that ozone in the stratosphere is important because it blocks cancer-causing UV radiation, ozone near Earth’s surface can harm human and plant health; higher in the troposphere, it is a potent greenhouse gas and can lead to more warming. Most lightning is intracloud – this means the NOx created remains high up in the atmosphere, where it can do more damage. Lightning-induced NOx doesn’t hold a candle, percentage-wise, to other greenhouse gases like carbon dioxide and methane when it comes to damaging effects, but that may change as climate continues to warm and the chemistry of our atmosphere continues to change.
photo: U. Peña, still shot from video shot on airplane from Flagstaff, AZ to Colorado.