The findings reveal important links to extreme temperatures in the Northern Hemisphere

Over the past few decades, heat waves have been hot in the Northern Hemisphere. It is home to about 90% of the world’s population, with the largest proportion living in mid-latitudes, with more frequent and severe heat waves and droughts occurring in the Northern Hemisphere in 2003, 2010, 2019, 2018 and 2021, and in the eastern part of 2013 and 2022.

Given the great causality and economic losses, it is frustrating that predicting these events with global computer models is even more difficult outside the tropical regions of the Earth.

Today, Chinese scientists have shown that major global climate connections have been changing since the late 1970s, changing the effects of the most severe heat waves and droughts in Eastern Europe, East Asia and Southwest North America. Their work is featured in Nature Communications.

Both empirical observations and modelling evidence illustrate the essential role of the El Niño Southern Oscillation (ENSO) behind this change.

Before the late 1970s, ENSO indirectly influenced the outward circirconect in the northern summer in a way that modulated the Indian summer monsoon. That link began in the 1980s when the ENSO displaced westward, causing a shift in the previous center of the GCT.

El Niño and Southern vibrations, Enso is an aperiodic change in wind and water temperature in the western tropical Pacific Ocean, appearing as El Niños (warm surface water) and La Niñas (cold surface water) in the central and eastern equatorial Pacific Oceans. These changes have global results, with the former often increasing the average world surface temperature, while the latter lowering the average world surface temperature, and also affecting rainfall in certain regions.

In an age of man-made global warming, as happened in 2023 and 2024, El Niños frequently leads to record temperatures. The “Southern vibration” occurs in the atmosphere and is linked to shifting sea surface temperatures.

ENSO patterns, which have been shown to be unpredictable, have a significant impact on tropical, rainfall, and crop production climates. Through “teleconnections,” they can affect distant parts of the globe, often thousands of kilometers away.

One is the Northern Summer (June to August) External Kabbalah Teleconnection (CGT) discovered in 2005, an atmospheric circulation abnormality in the upper troposphere that occurs during the summer of the Northern Hemisphere.

Using datasets of past climate and climate observations, we found that we had fallen into climate models, changing the structure and variability of CGTs since the late 1970s, and altered communications in the US in the Western North Pacific, another global scale. But at the time, it was only predictable almost a month ago.

The CGT is made up of Rossby waves (waves of waves present in the rotating fluid), and is associated with a jet stream in the northern hemisphere, where five wave numbers flow westward in the upper atmosphere.

A Chinese research team, Shankai Tang, the lead author of Sun Yat-Sen University in Zhuhai, China, and seven co-authors from China, and co-authors at the University of Hawaii in Manoa, found that the Rossby waves in the Northern Hemisphere had shifted by half the wavelength since the late 1970s.

It utilizes rainfall data compiled from the National Oceanic and Atmospheric Administration precipitation reconstruction, as well as global winds, rainfall, surface temperatures and global regional heights provided by the European Centre for medium-range weather forecasting. For statistical evidence of change, numerical experiments are performed to examine CGT.

Why does half-wavelength change? One obvious possibility is artificial climate change, but we discovered that the changes discovered cannot be simulated using 24 state-of-the-art climate models with known artificial forcing from the Coupled Model Intercomparison Project Phase 6.

Looking at the unusual summer Enso years, they discovered that the structure of summer summer has undergone major changes over decades. (This change turns out to be the same for both El Niño and La Niñas.)

The descent movement of Walker Circulation suppressed convection and rainfall in the North Pacific Ocean in the western tropical region, resulting in rainfall. Through a series of atmospheric interactions, the results will be the half-wave western shift of the North Pacific Center in CGT and “and other downstream centers.”

The group says their work could help improve future models for forecasting and forecasting. “A deeper understanding of recent changes in CGT structure should help improve seasonal predictions of central Northern Hemisphere heat waves and droughts associated with ENSO,” they wrote.

A better understanding of the ENSO-CGT relationship should also improve forecasts of future climate change in regions in the same central location.

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