Global warming may increase the risk for extreme rainfall and drought. This is according to new evidence from a NASA-led study, accepted for publication in the American Geophysical Union journal Geophysical Research Letters, which provides a new assessment of global warming’s impacts on precipitation patterns around the world.
For the first time, environmental wellness experts have shown how rising carbon dioxide concentrations could affect the entire range of rainfall types on Earth. This is based on an analysis of computer simulations from 14 climate models, which indicates that wet regions of the world, such as the equatorial Pacific Ocean and Asian monsoon regions, will have even heavier precipitation in the years to come.
As well as the impact that warming resulting from projected increases in carbon dioxide levels will have on wet regions, the study has found that arid land areas outside the tropics and many regions with moderate rainfall could become drier. According to William Lau of NASA’s Goddard Space Flight Centre in Greenbelt, Maryland, and lead author of the study, ‘In response to carbon dioxide-induced warming, the global water cycle undergoes a gigantic competition for moisture resulting in a global pattern of increased heavy rain, decreased moderate rain, and prolonged droughts in certain regions.’
So does this mean you might have to carry an umbrella a little more or less often, or are there larger risks to your wellbeing at play here? Lau explained, ‘Large changes in moderate rainfall, as well as prolonged no-rain events, can have the most impact on society because they occur in regions where most people live. Ironically, the regions of heavier rainfall, except for the Asian monsoon, may have the smallest societal impact because they usually occur over the ocean.’
When Lau and his colleagues analysed the model results, they were than able to calculate statistics on the rainfall responses for a 27-year control period at the beginning of the simulation, as well as for 27-year periods around the time of doubling and tripling of carbon dioxide concentrations. The authors concluded that the model predictions of how much rain will fall at any one location as the climate warms are not very reliable. However, Lau added, ‘if we look at the entire spectrum of rainfall types we see all the models agree in a very fundamental way – projecting more heavy rain, less moderate rain events, and prolonged droughts.’