A study published today by the journal Science has predicted that global warming could lead to an increase in lightning strikes across the United States (U.S.) over the next century. The study, co-authored by David Romps, predicts that lightning strikes could double in the United States by 2100 if climate models predicting the rising of the earth’s temperature are correct.
According to Romps, who is a researcher in Berkeley at the University of California, every two strikes that occur in the U.S. in 2000 will be matched by three in 2100. This increase in lightning strikes can be caused by the earth rising in temperature by just a few degrees Celsius, which has been predicted to happen due to global warming. According to the Washington Post, Romps goes on to explain that two main factors are needed in the atmosphere for lightning to occur. The first is precipitation and the second is atmospheric instability. This instability lets air rise quickly which then suspends that precipitation and generates charged separation. Lightning occurs when a spark moves to a negatively charged portion of a cloud from a different place that has an opposite charge.
Researchers examined how the two factors would change in different climate scenarios and how that change would affect the amount of lightning. Convective available potential energy (CAPE), the technical term for the combination of precipitation and instability that causes lightning, will increase and therefore the number of lightning strikes will rise accordingly. It is also possible that a rise in favorable storm conditions will also contribute to such an increase.
According to the study that predicted that the number of lightning strikes could increase due to global warming, CAPE accounts for 77 percent of variability in flashes of lightning in the U.S. The study used 11 different models on climate change to see how potential changes in CAPE would affect the lightning. The models were detailed scenarios that were run as simulations on computers that are designed to observe and predict the effects of possible climate changes. The study found that for every degree Celsius of global warming there would be a 12 percent rise in lightning. This results in a rise of 50 percent over the next century as long as current predictions on global warming remain the same.
This increase in lightning strikes that global warming could lead to is important for several reasons. While not many people are killed by lightning strikes in the United States, between 23 and 48 per year, lightning is the cause of around 50 percent of the wildfires in the nation. A rise in lightning strikes will have an effect on the composition of greenhouse gases in the atmosphere as well. More lightning will mean an increase in ozone, however, nitrogen oxides are produced by lightning and they reduce methane levels. Both ozone and methane are harmful greenhouse gasses. The results of the study only apply to the U.S. and are based on information from the National Lightning Detection Network and the U.S. National Oceanic and Atmospheric Administration.
By Clara Goode
Photo Source: Walid Mahfoudh – Flickr License