Floods and droughts are getting worse: extreme events will be more and more intense

If you look at extreme events, 2022 was a record year for Italy. But the upward trend is much broader and extends well beyond national borders, and does not only concern the number of events themselves. While we were making record after record of global temperaturesthey also grew up floods and droughtsincreasingly intense, says today a study published in nature water, with different trends around the world. Enough look at us from space to understand it.

This is indeed the case, thanks to observations from the GRACE and GRACE Follow-on satellites, that Matthew Rodell And Bailing Li of NASA Goddard Space Flight Center in Greenbelt were able to monitor drought and flood events, recording their frequency and duration. They did so by focusing on the so-called anomalies of terrestrial water storage (Total Water Storage, TWS in English), or rather on the quantity of water contained above the earth's surface and below. A method different from others, such as those based on the analysis of rainfall or ofhumidity and which would allow for a more complete view of extreme events when it comes to water, explain the authors. Over a thousand events analyzed globally, with a slight predominance for drought events.

Within the period analyzed - from 2002 to 2021 - the authors identified a particularly critical time window. It is the one that goes from 2015 to 2021, when, in conjunction with the increase in global temperatures to record levels, there was also a increase in extreme events: from three per year in previous years to four per year. When we talk about extreme events in these cases we are referring to phenomena of considerable importance, such as the one that in Africa - topping the list of "wettest" events - raised the water levels of the Lake Victoriaamong the largest in the world, between 2020 and 2021. On the other hand, at the top of the list of the "driest" events is the one that hit the Amazon forest between 2015 and 2016. The region of South America it is one of the most affected by extreme events: about a third of the wettest and driest events of the last twenty years map in these areas, the authors recall. But the researchers also don't forget the drought that in 2021, and therefore in the following year, affected (and is affecting) theEurope.

From new reservoirs to desalination plants, this is how Italy fights against drought

by Elena Dusi

March 14, 2023

Precisely in these areas, the trend in recent years is towards increasingly greater drought events (unlike the equatorial regions, more affected by floods). A worrying trend in terms of the availability of fresh water reserves and, as a consequence, for food, health and migratory flows, the authors conclude.