From the UNIVERSITY OF EDINBURGH: Lightning storms less likely in a warming planet, study suggests
Lightning may strike less often in future across the globe as the planet warms, a scientific study suggests.
The research forecasts a 15 per cent drop in the average number of lightning flashes worldwide by the turn of this century, if global temperatures are in the top range of forecasts.
A drop in the incidence of lightning strikes could impact on the frequency of wildfires, especially in tropical regions.
It could also lower the incidence of lightning strikes to infrastructure and affect how greenhouse gases in the atmosphere contribute to climate change.
Scientists from the Universities of Edinburgh and Leeds and Lancaster University used a newly devised method to calculate the likely incidence of lightning flashes from storm clouds.
Unlike traditional calculations of lightning flashes at the global scale, which are based on the height of clouds, their approach takes into account the movement of tiny ice particles that form and move within clouds. Electrical charges build up in these ice particles, and in cold water droplets and soft hail formed inside clouds. These are discharged during storms, giving rise to lightning flashes and thunder. Scientists estimate there are 1.4 billion lightning flashes each year around the world.
The latest results, accounting for a 5C rise in global average temperatures by the year 2100, show that on average lightning flashes are less likely in future, in contrast to previous studies.
Scientists previously verified their method by applying it to current conditions. The research, published in Nature Climate Change, was funded by the Natural Environment Research Council.
Dr Declan Finney of the University of Leeds, formerly of the University of Edinburgh, who carried out the study, said: “This research questions the reliability of previous projections of lightning, and encourages further study into the effects of climate change on cloud ice and lightning.”
Professor Ruth Doherty, of the University of Edinburgh’s School of Geosciences, said: “This research expands our current knowledge of climate change impacts on lightning and suggests that in a warmer world, the incidence of lightning is likely to decrease.”
Professor Oliver Wild, Of Lancaster University, said: “The results provide new insight into the likely impacts of lightning on future atmospheric composition and climate.”
The finding is interesting, and contradictory some claims of increased severe weather that is expected due to warming. Usually, lighting frequency and intensity increases with thunderstorm magnitude, and large thunderstorms are more likely to produce torrential rainfall (flash flooding), destructive downburst winds, large hail, and tornadoes.
ADDED: (since the press release didn’t contain it) Of course, the study uses RCP 8.5 modeling, which is wildly overbiased, so take it with a grain of salt.
A projected decrease in lightning under climate change
Lightning strongly influences atmospheric chemistry1,2,3, and impacts the frequency of natural wildfires4. Most previous studies project an increase in global lightning with climate change over the coming century1,5,6,7, but these typically use parameterizations of lightning that neglect cloud ice fluxes, a component generally considered to be fundamental to thunderstorm charging8. As such, the response of lightning to climate change is uncertain. Here, we compare lightning projections for 2100 using two parameterizations: the widely used cloud-top height (CTH) approach9, and a new upward cloud ice flux (IFLUX) approach10 that overcomes previous limitations. In contrast to the previously reported global increase in lightning based on CTH, we find a 15% decrease in total lightning flash rate with IFLUX in 2100 under a strong global warming scenario. Differences are largest in the tropics, where most lightning occurs, with implications for the estimation of future changes in tropospheric ozone and methane, as well as differences in their radiative forcings. These results suggest that lightning schemes more closely related to cloud ice and microphysical processes are needed to robustly estimate future changes in lightning and atmospheric composition.