Page 30 - bne IntelliNews monthly magazine May 2024

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the latest IPCC report, using the high-end warming scenario. Purple shows areas where precipitation will increase, orange indicates less future rain and snow, and the dots indicate where nine out of ten climate models agree.
“The average of the models shows large increases in precipitation near the equator, particularly in the Pacific Ocean. They also show more precipitation in the Arctic and Antarctic, where cold temperatures currently limit how much water vapour the air can hold,” a note by Carbon
“Unlike average annual precipitation, almost the entire world is expected to see an increase in extreme precipitation as it warms”
Brief explained. “The Mediterranean region is expected to have around 20% less precipitation by 2100 in a [high end 4C warming assumption] world, with similar reductions also found in southern Africa. Western Australia, Chile and Central America/Mexico may all become around 10% drier.”
However, a lot of uncertainty surrounds the changing rainfall predictions. The above chart is based on an averaging of the 39 different climate models used by IPCC and many of them give very different predictions of what will happen to rainfall patterns over the long term. In at least one model much of the world outside high-latitude areas and the tropical oceans
shows sizable drying and there is at least one model where nearly any given location in the world gets wetter.
But there is widespread agreement among the models that both the tropical Pacific and high-latitude areas will have more precipitation in the future. India, Bangladesh and Myanmar will all become wetter, as will much of northern China.
The models largely agree that the Mediterranean region and southern Africa will have less precipitation in the future. They also agree on reduced precipitation in southwest Australia around Perth, in southern Chile, the west coast of Mexico and over much of the tropical and subtropical Atlantic ocean.
Interestingly, despite all the focus on drought in the state of California, there is no consensus among climate models that the region will experience less precipitation on average in a warmer world.
Models also generally agree that precipitation, when it does occur, will become more intense nearly everywhere. Unlike average annual precipitation, almost the entire world is expected to see an increase in extreme precipitation as it warms. The science suggests that while a one degree rise in temperature leads to a 7% increase in water vapour, it also results in a 15% increase in extreme rain, especially at higher elevations, according to research published in Nature.
Models suggest most of the world will have a 16-24% rise in heavy precipitation intensity by 2100. In other words, heavy rain is likely to get heavier. In the map red areas show decreases in heavy precipitation, while blue areas indicate increases.
Percent change in heavy precipitation per degree warming, defined as the heaviest daily precipitation event of the year for each location. Figure adapted from Fischer et al 2014.
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