How is climate change affecting rainfall today? Researchers at the National Center for Atmospheric Research (NCAR) have tried to answer this question. To do so, they have developed an innovative approach, based on precipitation weather data from the last century (1921-2015). The study shows unequivocally that human-induced climate change in recent decades has influenced precipitation over the last 100 years.
How is climate change affecting rainfall today? Researchers at the National Center for Atmospheric Research (NCAR) have tried to answer this question. To do so, they have developed an innovative approach, based on precipitation weather data from the last century (1921-2015).
They have elaborated them from advanced large-scale atmospheric circulation models and analyzed them using statistical techniques and climate simulations. In doing so, they have shown that there have been important variations in the amount of precipitation affecting the entire northern hemisphere of the Planet (Eurasia and North America).
In some regions it decreased significantly, in others it increased radically.
The Results of the Study on Rainfall Today
The study shows unequivocally that human-induced climate change in recent decades has influenced precipitation over the last 100 years. On the one hand, since 1920, precipitation has increased in North Eurasia and North America. On the other hand, a significant decrease has occurred in the central regions of the United States and southern Eurasia.
The authors of the study (published in the Geophysical Research Letters) found that, globally, there is an increase in precipitation of 1-2 percent for each degree above atmospheric temperature. This is due to the fact that there is greater evaporation of the oceans. But the complex system of atmospheric circulation means that precipitation is not uniform everywhere. In some regions of the world, the amount could decrease, and not just a little.
A New Research Method
As the researchers themselves admit, the work has been very complex. This is because it is difficult to separate natural and man-induced climate variability. First of all, the study took winter periods into account. These are in fact easier to study from the point of view of atmospheric circulation. The team first determined statistically the amount of rain that fell during the various years. Then they calculated the possible natural variations. On the basis of these data, it emerged that the increase or decrease in precipitation could only depend on human-induced climate change.
This was verified step by step by comparing the actual data with what the models showed. So the researchers were able to refine the latter to make them agree with reality in the best possible way. The method has proven to be very reliable. In fact, it will now be used to get accurate rainfall forecasts for the coming decades, depending on various temperature increase scenarios.
