Flirting with climate danger: UN predicts 2 in 3 chance of hitting key heat limit soon

There is a two in three chance within the next five years that the world will temporarily reach the internationally accepted global temperature threshold to limit the worst effects of climate change, a new report from the World Meteorological Organization predicts.

It would likely only be a passing and less ominous flirtation with the agreed climate danger point, the United Nations weather agency said on Wednesday. That’s because scientists expect a temporary burst of heat from an El Niño to amplify human-caused warming from burning coal, oil and gas to new highs and then back down. A little.

The 2015 Paris climate agreement set 1.5°C (2.7°F) as a global guardrail to atmospheric warming, with countries pledging to try to prevent as much warming over the long term if possible. In a 2018 United Nations special report, scientists said that going beyond that point would be radically and dangerously different, with more death, destruction and damage to global ecosystems.

“It probably won’t be this year. Maybe it will be next year or the year after,” said the report’s lead author, Leon Hermanson, a climatologist at the UK’s Met Office.

Why it doesn’t mean we haven’t reached the Paris target

But climate scientists said what is likely to happen over the next five years is not the same as missing the global target.

“This report does not mean we will permanently exceed the 1.5C level specified in the Paris Agreement, which refers to long-term warming over many years. ‘alarm that we will temporarily exceed the 1.5C level with increasing frequency,’ WMO Secretary-General Petteri Taalas said in a statement.

A temperature chart is shown as Petteri Taalas, Secretary General of the World Meteorological Organization, speaks about the global climate update with forecasts for 2023-2027 in Geneva, Switzerland, May 17. (Martial Trezzini/Keystone via The Associated Press)

“A single year really doesn’t mean anything,” Hermanson said. Scientists generally use 30-year averages.

That 66% chance of a single year hitting that threshold in five years has gone from 48% last year, 40% the year before, 20% in 2020 and 10% about ten years ago. The WMO report is based on calculations made by 11 different climate science centers around the world.

The world has been approaching the 1.5°C threshold due to human-induced climate change for years. The temporary El Niño warming expected this year – a phenomenon that begins by warming parts of the central Pacific Ocean and then spreads across the world – allows us “to see a single year exceed 1.5 C a whole decade before the long-term average warming caused by human emissions of greenhouse gases does,” said climate scientist Zeke Hausfather of tech firm Stripe and Berkeley Earth, who was not part of the report. WMO.

“We don’t expect the longer-term average to exceed 1.5°C until the early to mid-2030s,” Hausfather said in an email.

Why it’s always a big deal

But every year at or near 1.5 C counts.

“We see this report as a barometer of how close we are getting, because the closer you get to the threshold, the more noise going up and down is going to cause you to randomly cross the threshold,” Hermanson said in an interview. . And he said the more random bumps there are on the mark, the closer the world gets to the threshold.

WATCH | Scientists give ‘final warning’ on climate change in UN report:

Scientists give ‘final warning’ on climate change in UN report

Top climate scientists have released their final assessment report on climate change, saying this is the last chance to limit human-caused global warming to 1.5C above pre-industrial levels before damage does not become irreversible.

The key to all of this is the El Niño cycle. The world is emerging from a record-breaking La Niña triple trough — three straight years of El Niño’s cooler cousin limiting the rise of human-caused warming — and is on the verge of an El Niño that some scientists predict will be strong. .

La Niña flattened the trend of human-induced warming somewhat, so the world hasn’t crossed the annual temperature mark since 2016, in the middle of the last large El Niño, Hermanson said.

Some bad news, some good news

And that means a 98% chance of breaking the 2016 annual global temperature record by 2027, according to the report. There is also a 98% chance that the next five years will be the five hottest years on record, according to the report.

Due to the shift from La Niña to El Niño. “Where there were floods before, there will be droughts and where there were droughts before, there could be floods,” Hermanson said.

The report warns that the Amazon will be abnormally dry for much of the next five years while the Sahelian part of Africa – the transition zone between the Sahara in the north and the savannahs in the south – will be wetter.

That’s “one of the positive things coming out of these predictions,” Hermanson said. “It’s not all doom and gloom and heat waves.”

WATCH | “They don’t believe the rains are coming again:” Witnesses to the devastating drought in Somalia:

‘They don’t believe the rain is coming’: Witnesses to the devastating drought in Somalia

CBC’s Margaret Evans reflects on what she witnessed in drought-ravaged Somalia and the depth and breadth of the famine crisis after five failed rainy seasons. Plus, International Development Minister Harjit Sajjan on what more Canada can do to help.

University of Pennsylvania climatologist Michael Mann said reports like this place too much emphasis on global surface temperature, which varies with the El Niño cycle, even as it increases over the long term.

The real concern is the deep ocean water, which is absorbing an overwhelming majority of human-caused global warming, causing ocean heat content to steadily rise and new records to be set regularly.

Mann said it’s wrong to think the world is on the verge of crossing the threshold at any time, because “a concerted effort to reduce carbon emissions can still avoid crossing it altogether,” Mann said. “That’s what we need to focus on.”

Leave a Comment