Model calculations over decades have predicted that heavy rainfall would be more severe in a warmer world. This is now confirmed by the study of global data.
the manOn Caused global warming has intensified the heavy rainfall in the past few decadesAnd the And globally – exactlyAs predicted by climate modelskilling. This one is currently featured in the trade journal “Nature Communication” Published study. “Methodologically and in terms of data sets, this is probably the most complete study demonstrating human impact on heavy rainfall,” says climate researcher Reto Knotti of ETH Zurich, who was not involved in the study.
It is not easy to determine the direction of heavy rainfall in meteorological data for several reasons. “Precipitation measurements are known to be very difficult,” Knutti says. The measuring tools are different, the quality at least is not always good in the past. “Plus, the stations only measure at one location that usually doesn’t even represent an area during a thunderstorm.” Since the natural variability in heavy precipitation is also very high, long time series with sufficient spatial resolution are required to be able to establish the trend. “Availability of data is often the limiting factor.”
AI trained with climate models
For the current study, climate researchers working with Gavin Madakumbura of UCLA developed an artificial intelligence (AI) – a so-called neural network – depending on Climate models were trained on patterns of heavy precipitation. In the second step, the trained AI searched for patterns corresponding to heavy precipitation in the measurement data from 1982 to 2015. The authors were able to determine their intensification as a result of man-made warming in several measurement series around the world.
This was already achieved earlier for individual countries or continents. in 2016 im “Journal of Geophysical Research: Atmosphere” A study published on Switzerland showed an increase in heavy rainfall since 1901, both in frequency and intensity. However, the development is not very clear due to the strong and increasing natural variability of heavy precipitation.
What Knutti found particularly exciting about the study in Nature Communications is that the observations now also globally confirm what climate models have been predicting for decades. “Since 1850, thanks to thermodynamics, we’ve known that the atmosphere can absorb about seven percent more moisture per temperature.” So it’s clear that the same thunderstorm could bring 15 percent more water in a world two degrees warmer, and thus increase the risk of damage without adaptive measures. “The increase in heavy precipitation was simulated and described using climate models over 30 years ago,” Knutti says. “Today the data confirms that.”