Conducted by scientists from the CICERO Center for International Climate Research, in collaboration with the University of Reading, the study projects that around 70% of the population will experience these risks if insufficient action is taken. However, if emissions are reduced in line with the Paris Agreement, this figure could drop to 20%.

The findings, published in 'Nature Geoscience', reveal how global warming, when combined with normal weather variations, can create decade-long periods of rapid shifts in extreme temperatures and rainfall patterns.

Dr. Carley Iles, the lead author of the study at CICERO, explained: "We focus on regional changes, due to their increased relevance to the experience of people and ecosystems compared with the global mean, and identify regions projected to experience substantial changes in rates of one or more extreme event indices over the coming decades."

Projected Impact on the Tropics and Subtropics

The study's large climate model simulations predict that vast areas within the tropics and subtropics, covering 70% of the current population, are expected to see rapid changes in temperature and precipitation extremes under a high-emissions scenario. With robust emissions mitigation, this number could fall to approximately 20%, or around 1.5 billion people.

Such rapid changes bring heightened risks of unprecedented weather conditions. These include extreme events that contribute significantly to the impacts of climate change. Heatwaves, for instance, may lead to heat stress, increased mortality rates for both people and livestock, ecosystem damage, and reduced agricultural productivity. They could also affect infrastructure, such as power plants and transportation systems. Similarly, extreme rainfall events might cause flooding, infrastructure damage, crop losses, erosion, and reduced water quality, exacerbating societal vulnerability when multiple hazards arise simultaneously.

Air Pollution and Extreme Weather Trends

Co-author Dr. Laura Wilcox from the University of Reading noted: "We also find that rapid clean-up of air pollution, mostly over Asia, leads to accelerated co-located increases in warm extremes and influences the Asian summer monsoons. While cleaning the air is critical for health reasons, air pollution has also masked some of the effects of global warming. Now, the necessary cleanup may combine with global warming and give very strong changes in extreme conditions over the coming decades."

While the study focuses on the likelihood of rapid change, the authors stress that these findings have significant implications for climate adaptation strategies. Dr. Bjorn H. Samset from CICERO Center for International Climate Research, who contributed to the study, emphasized: "In the best case, we calculate that rapid changes will affect 1.5 billion people. The only way to deal with this is to prepare for a situation with a much higher likelihood of unprecedented extreme events, already in the next 1-2 decades."