Die droughtswhich are becoming more and more common Western United States and other areas of the world, including the Mediterranean basin, have traditionally been cyclical phenomena Rainfall scarcity zugeschrieben.
However, new research shows that the true determining factor is man-made Climate change which, due to warming temperatures, has a much greater influence than previously assumed.
The study, which focuses on the western United States and was conducted by experts from the University of California, Los Angeles (UCLA) and the National Oceanic and Atmospheric Administration (NOAA) was carried out, emphasizes that the increase in evaporation through global warming is now the main cause of the drought conditions in the region, especially since the 2000s. In the critical period between 2020 and 2022 The analysis showed that the contribution of evaporation on the severity of the drought 61% was, while the reduction in rainfall only 39% made up.
According to the professor Rong Fulead author of the study and professor of Atmospheric and Oceanic Sciences at UCLA, it was already known that high temperatures promote droughts, but this research clearly shows that the loss of moisture through evaporation has a greater weight than the simple lack of precipitation. This new view represents a change in perspective: Historically, the droughts in the western United States as meteorological phenomena interpreted as being associated with periods of low rainfall.
Thanks to this study, it is now clear that the increase in global temperatureswhich is largely caused by the combustion of fossil fuels caused by increased evaporation demand, which influences the frequency and severity of droughts.
This forces us to change our approach Water crisis and to rethink the mitigation strategies, whereby the human activities and their impact on the climate must be taken into account. The managing director of National Integrated Drought Information System of NOAA, Veva Dehezaco-author of the study, emphasized that this change in perspective represents a new paradigm.
The ever-increasing temperatures create extreme droughtsand in this context the role of precipitation becomes secondary. the climatic balance is extremely complex.
Global warming increases evaporation rates, and although a warmer atmosphere produces larger amounts Water vapor can hold, this does not automatically lead to precipitation.
In fact, the heat keeps them Water molecules in constant motion, what the condensation and thus hinders the formation of precipitation.
This mechanism, through the Rise in temperatures appears to characterize longer periods of drought, extending over larger areas and characterized by increasingly severe drought conditions. When examining the data of the last 70 years the scientists have the natural droughts compared to those influenced by human-caused climate change.
The results show that 80% of the increase of Evaporative demand, that has been observed since 2000, is due to climate change, a percentage that has increased during drought periods 90% exceeds. This clearly shows that climate change is the main driver of the increase in the severity and extent of droughts since 2000 . The implications of this discovery are significant: the challenge of Water resources management in the western United States requires a new strategy that takes into account not only precipitation, but also the impact of rising temperatures on water reserves.
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