In 2015, in Paris, the world’s countries committed themselves to do their best to limit the warming of the planet to more than 1.5°C above its pre-industrial state. Even at the time the goal seemed ambitious. In recent years, it has started to seem almost impossible.
On 17 May the World Meteorological Organization (WMO), a branch of the United Nations, added to the gloom. It said there was a 66% chance the world would exceed the 1.5°C threshold in at least one of the next five years. This is a huge jump from its projections from a year ago, when the WMO assessed the probability at 48%. Even if the 1.5°C target is not breached, the WMO thinks it is certain that the coming five years will be one of the warmest in human history. (This record now stands until 2016, which was 1.28 °C warmer than the pre-industrial average.)
Optimists point out that even if the 1.5°C limit is exceeded, it will only be temporary, and will not technically violate the Paris Agreement—yet. (This would require exceeding the target by several years.) The increase would be temporary as the rising level of human-driven warming would be further amplified by natural, but transient, changes for the next few years.
The largest of those variations is the El Niño Southern Oscillation (ENSO), a natural cycle of warming and cooling in the waters of the eastern Pacific Ocean that has wide-ranging effects on climate. The world has seen three consecutive “La Niña” years, the name given to the cold phase of the cycle, helping to keep global temperatures down. It is now almost certain that the warm “El Niño” phase will begin sometime later this year, setting up 2024 to be a scorer. (One reason for 2016’s record is that the year coincided with a particularly strong El Niño.)
But ENSO is not the only factor. Last year’s eruption of the Hanga Tonga-Hanga Ha’apai volcano near Tonga may have provided an additional temporary nudge. It was one of the largest eruptions since Mount Pinatubo in the Philippines in the 1990s, and injected an estimated 146m tonnes of water vapor into the stratosphere. Water vapor, like carbon dioxide, is a greenhouse gas. Unlike carbon dioxide, it will slowly fall out of the stratosphere over the next few years. But Stuart Jenkins, a climatologist at the University of Oxford, believes that as long as it persists, it could increase the odds of exceeding 1.5°C by a few percentage points.
Some tentatively encouraging signs flashed amid the gloom. Global emissions of greenhouse gases from fossil fuels seem to have gone unidirectional for several years, leading some researchers to talk cautiously about a possible peak. Rystad Energy, a Norwegian think-tank, predicted earlier this year that global emissions of carbon dioxide from industry could peak in 2025 and then begin a slow decline.
But so far, despite the warm words, the world’s actions still fall far short of its promises. Even the upper end of the targets agreed in Paris – to limit warming to “well below 2°C” – can only be achieved with drastic action. For Europe and the US to meet their commitments, for example, they would need to shut down all of their fossil-fired power plants within the next three decades.
And simply stopping emissions will not be enough. Somewhere between 3.5bn and 5.4bn tonnes of carbon dioxide would need to be taken out of the atmosphere each year, rising to 4.7bn to 9.8bn tonnes within 30 years. To put it mildly, this is all a big ask. But the optimist may take the view that the psychological effect of exceeding the 1.5°C target, even if only temporarily, may help focus.
© 2023, The Economist Newspaper Limited. All rights reserved. From The Economist, published under license. Original content can be found at www.economist.com
catch all business News, market news, today’s fresh news events and Breaking News Update on Live Mint. download mint news app To get daily market updates.