Climate Precipitation variability has increased significantly in Europe
Europe is one of the regions of the world where the variability of precipitation has increased particularly sharply since 1900. This is the conclusion reached by a Chinese research team after analyzing various rainfall data sets from 1900 to 2020.
28.07.2024, 04:28
SDA
On a global average, variability increased by 1.2 percent per decade during this period, with the trend being particularly pronounced since the 1950s. Using computer simulations, the team led by Tianjun Zhou from the Chinese Academy of Sciences in Beijing sees the cause of the trend in man-made climate change in the journal "Science".
The team defines precipitation variability as irregularities in the timing and amount of precipitation. Higher variability means that precipitation is distributed more unevenly over time, which can lead to wetter rainy periods and drier dry periods. "The increased variability in precipitation we have observed provides crucial evidence of larger daily changes that make it more difficult to predict and prepare for environmental impacts," Zhou is quoted as saying in a statement from his institution.
Warmer and wetter atmosphere due to greenhouse gas emissions
The researchers used five global and eight regional long-term data sets on precipitation as the basis for their calculations. Based on precipitation data from the Global Historical Climatology Network - the main data set used - they determined that precipitation variability increased over 80 percent of Europe's land area during the study period. In eastern North America, the figure is as high as 89 percent, while the global average is 75 percent. "The consistency over several observation series confirms the robustness of the increase trend," the authors write.
Zhou and his team then used an established climate model (CMIP6) to attribute the increasing precipitation variability to various causes: Changes of natural origin, greenhouse gas emissions and aerosols of man-made origin. It was found that the increase in precipitation variability was mainly due to human-induced greenhouse gas emissions, which have led to a warmer and wetter atmosphere.
"This means that even if the atmospheric circulation remains the same, the extra moisture in the air leads to more intense rainfall and more drastic variations in it," said first author Wenxia Zhang.
New challenges for weather forecasts
Man-made aerosols, for example from particulate matter, have less influence on the variability of precipitation today than in the past. This is probably due to global efforts in recent decades to make the air cleaner.
However, this trend is being overshadowed by the sharp rise in greenhouse gases in the atmosphere. "Increased precipitation variability poses new challenges for weather and climate predictions as well as for the resilience and adaptation of societies and ecosystems," write the study authors.
