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Climate change can lead to overflow of “heavenly rivers”

Climate change can lead to overflow of "heavenly rivers"

By the end of the century, atmospheric rivers are likely to become rarer, but more "deepwater" phenomenon.

By the end of the century, for the greater part of the globe, extreme weather events, known as atmospheric rivers, are likely to become more "deep-water". However, the total amount due to climate change will decrease slightly. This conclusion was made by NASA specialists.

We will explain that by the term "atmospheric rivers" are understood to be long and narrow jets of air carrying a huge amount of water vapor from the tropics to the more temperate latitudes. The width of such "celestial rivers" usually ranges from 400 to 600 kilometers. And usually they carry as much water in the form of water vapor, how many could contain 25 rivers like Mississippi.

When an atmospheric river collapses on the coast, especially when colliding with a mountain massif (such as the Sierra Nevada or the Andes), most of the water vapor precipitates on land in the form of rain or snow.

Such systems are not a rare phenomenon: at any moment the Earth can boast an average of about 11 "celestial rivers". In many parts of the world, they bring the necessary precipitation, and they make an important contribution to the annual fresh water supply. However, more powerful atmospheric rivers can cause catastrophic floods.

Until recently, scientific work on the study of climate change (which would affect, among other things, atmospheric rivers) was limited to only two regions of the world: the US West and Europe. Since usually specialists use different methods for determining "celestial rivers" and various models of climate prediction, the conclusions of one work could not be quantitatively compared with the data of the other.

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This time NASA scientists used a more rational and global approach to assess the effects of climate change affecting atmospheric rivers.

The authors of the work relied on two resources: a set of widely used forecasts of global climate models for the 21st century and an algorithm for detecting atmospheric rivers, which can be applied to the results of the climate model.

It is noted that the algorithm determines the length, width of atmospheric rivers, as well as the amount of water vapor that they carry.

NASA specialists used the algorithm for detecting atmospheric rivers both from actual observations and from the model of the late 20th century. Further comparison of the data showed that the models give a relatively realistic view of the atmospheric rivers for the climate of the last century.

After the scientists applied the algorithm, using the data of the climate model of the late 21st century. Later, they also compared the occurrence frequency and characteristics of atmospheric rivers for the current climate with predictions for the future.

According to forecasts, the atmospheric rivers will become much longer and wider than those that are observed today.

"The results of the work show that in the case of a scenario in which greenhouse gas emissions remain at today’s level, by the end of the 21st century the world will be about 10 percent less than atmospheric rivers"”Said lead author of the study Duane Waliser of NASA’s Jet Propulsion Laboratory.

Nevertheless, says Valiser, the results show that the atmospheric rivers will on average be 25 percent wider and longer, which means that heavy rains and strong winds will occur about 50 percent more often.

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Also researchers "fed" algorithm data of climate models, which assumed a more modest increase in the rate of greenhouse gas emissions. In this case, they received similar, albeit less radical changes. Specialists concluded that there is a direct connection between the extent of warming and the frequency and even severity of weather phenomena determined by atmospheric rivers.

Scientists say that the study has a double significance. First, knowledge of how atmospheric rivers can change in future climatic conditions will help scientists to anticipate the potential consequences of these changes. This is especially true for residents of places exposed to atmospheric rivers. It is about North Africa, New Zealand and Western Europe.

Secondly, a new approach allows us to explore atmospheric rivers at the global level. The work provides a basis for analysis and comparison, which was not previously at all.

The results of the study were presented in the scientific journal Geophysical Research Letters.

Earlier, we recall, "Vesti.Nauka" (nauka.vesti.ru) talked about the impact on the weather of air "stoppers" and giant ocean whirlpools, as well as the very unexpected effects of melting glaciers (spoiler: the rivers will not become fuller). In addition, we wrote about China’s attempts to change the global map of precipitation.

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