A new study on the intensification of winter storms in the southern hemisphere calls for a revision of current predictions of climate variability models. And not for the better

MIT Technology Review Italy

So far, climate models have given ample space to the role played by winter storms in warming the poles. The results of these careful analyzes are analyzed by leading research institutes around the world, including the Weizmann Institute of Science, and then incorporated into the assessment report of the United Nations Intergovernmental Panel on Climate Change (IPCC).

A new study, published in “Nature Climate Change”, conducted by a team of scientists under the leadership of Rei Chemke of the Earth and Planetary Sciences Department at Weizmann has revealed a phenomenon that is in many ways troubling: the intensification of winter storms especially in the southern hemisphere in recent decades has already reached the levels forecast for the year 2080.

“A winter storm,” explains Chemke, “is a meteorological phenomenon that lasts only a few days. Taken individually, the climatic weight of each storm is close to zero. However, the long-term effect becomes evident when one evaluates the cumulative data collected over long periods of time as taken together these storms affect the transfer of heat, humidity and momentum within the atmosphere, affecting the various climatic zones of the earth“.

“An example of these close interrelationships is their role in regulating the temperature at the Earth’s poles,” continues Chemke. “Winter storms are responsible for the passage of heat from tropical regions to the poles. Without their contribution, the average temperatures of the poles would be around 30 ° C lower“.

In its laboratory at the Weizmann Institute, Chemke researches the physical mechanisms behind large-scale climate change. In particular, he asked whether these changes in climate models are caused by external factors, for example human activity, or can they be considered the result of internal fluctuations in the global climate system.. Analysis of climate models has shown that internal causes have failed to explain the speed of change over the past 20 years.

Furthermore, the researchers uncovered the physical process behind this progressive escalation of the storms. A growth rate analysis showed that changes in atmospheric jet streams over the past few decades have caused these escalations and the lack of current climate models to accurately reflect these changes.

Chemke and colleagues’ study has two immediate and considerable implications. First, it shows that not only are climate projections for the coming decades to be more stringent than previous assessments, but it also indicates that human activity could have a greater impact on the Southern Hemisphere than previously estimated. This means that swift and decisive action is needed in the first place to stop climate damage in this region. Secondly, a correction of the bias in climate models is required.

Climate scientists are tasked with defining more precisely the extent of damage that climate change is expected to cause and calling policy makers to take responsibility for the planet’s future. The system of climate models is not in question. So far it has played an essential role in helping to anticipate a long series of important phenomena. “Ours wants to be a contribution to continue in this direction. The models did a great job of predicting almost all parameters, ”says Chemke. “Changes in temperature, precipitation, sea ice and summer storms, for example, are all accurately simulated.”

Image by 0fjd125gk87 from Pixabay

(rp)

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