The World Meteorological Organization (WMO) has released an updated assessment of the world's global climate trends and it's a shock for those who think human-induced climate change is an issue for the distant future. They predict there is a 40 percent chance that one of the next five years will breach the 1.5ºC hotter than the pre-Industrial average set out to avoid in the Paris Climate Agreement. There is plenty of evidence rising temperatures are already doing local damage to many ecosystems, but 1.5ºC above baseline has been assessed as the point where the danger becomes global.
The prediction is made as part of the WMO's Global Annual to Decadal Climate Update, looking at what the 2020s have in store for us, climate-wise.
Looking just at the 2021-2025 period the report gives a 90 percent chance one year will be the hottest on record, exceeding the current record-holder, 2016. Annual temperatures experience cyclic fluctuations based on the El Niño/La Niña oscillation, as well as other more subtle variations. For all the disasters 2020 brought with it, its second half saw the Pacific in a La Niña phase, which is associated with lower global temperatures. Nevertheless, 2020 still managed to be the third hottest year on record, 1.2ºC above preindustrial levels. Once another El Niño occurs the annual record will almost certainly be broken, quite possibly taking the 1.5ºC barrier with it. Even future cool years are expected to be 1ºC above the baseline.
“These are more than just statistics,” said WMO Secretary-General Professor Petteri Taalas in a statement. “Increasing temperatures mean more melting ice, higher sea levels, more heatwaves and other extreme weather, and greater impacts on food security, health, the environment and sustainable development.”
Average temperatures can feel abstract, but the assessment predicts an increase in Atlantic Tropical Cyclones, relative to previous 5-year periods. The prediction was put together before Tropical Storm Ana launched what looks like being another overactive hurricane season before the season's official start. The WMO also predicts higher precipitation in Africa’s Sahel, where it might be welcomed, and at high latitudes, where it probably won’t be. Meanwhile, southwestern North America, already locked in an epic drought, is expected to get drier.
The 40 percent chance given to exceeding 1.5ºC is double that in the same report last year. Most of the difference is a result of an improved understanding of exactly what preindustrial temperatures were.
Most of the negative effects of a hotter world are gradual, with every fraction of a degree making them just a little worse. There may be tipping points, where major consequences such as melting glaciers or rainforests turned to savannah become almost impossible to reverse. However, even drawing on the expertise of 11 nations’ climate scientists the WMO can’t pinpoint where these will occur. Acknowledging all this, the world has set 1.5ºC above preindustrial temperatures as the threshold below which global temperatures need to stay. The number is written into the Paris agreement, but national commitments do not get close to meeting that goal, and it seems we will cross it, even if only temporarily, alarmingly soon.