Since the beginning of May, those massive floods in Rio Grande do Sul have made world headlines. In the state’s capital, Porto Alegre, the Guaíba river is more than five meters above its normal level, breaking a record set in 1941. The death toll is 149 and growing, with 108 still missing. The floods have displaced more than 600,000 people and directly or indirectly affected more than 2 million, in 446 of the 497 municipalities in the state.
A combination of factors makes these floods more likely. For instance, warm ocean temperatures in the tropical Pacific (still currently the case, even as El Niño starts to decay) is associated with these weather systems, as are abnormally warm tropical Atlantic temperatures, which add more moisture to the air brought south in the flying river.
In fact, we are already observing this. Compared with the floods in 1941, this time the excessive rainfall was concentrated in a much shorter period, meaning the water rose much faster. Future climate projections already indicate that a warmer atmosphere results in an intensification of the flying rivers from the Amazon into south Brazil and adjacent regions, and more precipitation.
We have analyzed results from state-of-the-art climate models that are able to simulate storms across South America in detail, just a few kilometers across. These indicate that extreme rainfall like that happening now is likely to become more frequent in the future, and such risks may in fact be underestimated by the previous generation of climate models.
www.bbc.com/news/articles/c2899kjv7zeo
www.msn.com/en-us/weather/topstories/floods-in-south-brazil-have-displaced-600-000-here-s-why-this-region-is-likely-to-see-ever-more-extreme-rain-in-future/ar-BB1mFkPU?ocid=msedgntp&pc=U531&cvid=9507a3ba87f446daa069ae39a1572026&ei=11
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