Ellen Phiddian
Cosmos science journalist
Dramatic changes in temperature and rainfall are coming for up to 70% of the world’s population in the next 20 years because of high greenhouse gas emissions, according to a new study.
A report, published in Nature Geoscience, finds that dramatic cuts to emissions would drop this figure to 20%.
The Norwegian and UK team of researchers used a large collection of climate model simulations to examine how quickly weather will change in the next two decades.
“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,” says lead author Dr Carley Iles, a researcher at the CICERO Center for International Climate Research, Norway.
The team modelled weather changes under 2 different scenarios outlined by the Intergovernmental Panel on Climate Change (IPCC).
Their “high-emissions” scenario assumes greenhouse gas emissions will continue to rise significantly, causing 3.3-5.7°C warming by the end of the century.
Their “low emissions” scenario assumes emissions decline to net zero by about 2075, and the world warms 1.3-2.4°C by 2100.
The independent project Climate Action Tracker estimates that current global policies will cause emissions and warming somewhere in between these two outlooks.
In the high-emissions scenario, the researchers found that big portions of the tropics and subtropics would see very high rates of change in temperature and rainfall extremes.
These areas account for about 70% of the world’s population.
Under the lower emissions scenario, 20% of the world’s population would experience these dramatic trends.
The researchers point out that fast-changing weather extremes can have “particularly strong impacts”, such as the dangers of extreme heatwaves and flooding in areas that aren’t accustomed to them.
“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,” says study co-author Dr Bjørn Samset, also at CICERO.
“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,” says co-author Dr Laura Wilcox, a researcher at the University of Reading, UK.
“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.”
