There’s a two-out-of-three chance within the next five years that the world will temporarily reach the internationally accepted global temperature threshold for limiting the worst effects of climate change, a new World Meteorological Organization report forecasts.
The United Nations’ weather agency warned that it would likely only be a brief and more manageable flirtation with climate danger level. Scientists expect that a brief burst in heat caused by an El Nino event will cause the human-caused global warming to reach new heights, and then drop back down.
The 2015 Paris climate agreement set 1. 5 degrees Celsius (2. 7 degrees Fahrenheit) as a global guardrail in atmospheric warming, with countries pledging to try to prevent that much long-term warming if possible. Scientists in a special 2018 United Nations report said going past that point would be drastically and dangerously different with more death, destruction and damage to global ecosystems.
“It won’t be this year probably. Maybe it’ll be next year or the year after” that a year averages 1. 5 degrees Celsius, said report lead author Leon Hermanson, a climate scientist at the United Kingdom’s Met Office.
But climate scientists said what’s likely to happen in the next five years isn’t the same as failing the global goal.
“This report does not mean that we will permanently exceed the 1. 5C level specified in the Paris Agreement which refers to long-term warming over many years. However, WMO is sounding the alarm that we will breach the 1. 5C level on a temporary basis with increasing frequency,” WMO Secretary-General Petteri Taalas said in a statement.
“A single year doesn’t really mean anything,” Hermanson said. Scientists usually use 30-year averages.
Those 66% odds of a single year hitting that threshold in five years have increased from 48% last year, 40% the year before, 20% in 2020 and 10% about a decade ago. The WMO report is based on calculations by 11 different climate science centers across the globe.
The world has been inching closer to the 1. 5-degree threshold due to human-caused climate change for years. The temporary warming of this year’s expected El Nino — a phenomenon that starts with a warming of parts of the central Pacific Ocean and then sloshes across the globe — makes it “possible for us to see a single year exceeding 1. 5C a full decade before the long-term average warming driven by human emissions of greenhouse gases does,” said climate scientist Zeke Hausfather of the tech company Stripe and Berkeley Earth, who wasn’t part of the WMO report.
“We don’t expect the longer-term average to pass 1. 5C until the early-to-mid 2030s,” Hausfather said in an email.
But each year at or near 1. 5 matters.
” “We view this report more as a barometer to see how close we are to crossing the threshold. The closer we get, the louder the noise will be, and the more likely it is that you’ll bump over at random,” Hermanson stated in an interview. He said that the more bumps above the mark, the closer we are to reaching the threshold.
The El Nino cycle is key to all of this. It is now on the verge of a strong El Nino .
The La Nina somewhat flattened the trend of human-caused warming so that the world hasn’t broken the annual temperature mark since 2016, the last El Nino, super-sized one, Hermanson said.
And that means a 98% chance of breaking the 2016 annual global temperature record between now and 2027, the report said. There’s also a 98% chance that the next five years will be the hottest five years on record, the report said.
Because of the shift from La Nina to El Nino “where there were floods before, there will be droughts and where there were droughts before there might be floods,” Hermanson said.
The report warns that Amazonia will remain abnormally dry during the next 5 years, while Sahel Africa — between the Sahara in the north and savannas in the south — is expected to be drier.
That’s “one of the positive things coming out of this forecast,” Hermanson said. “It’s not all doom-and-gloom and heat waves.”
University of Pennsylvania climate scientist Michael Mann said reports like this put too much emphasis on global surface temperature, which varies with the El Nino cycle, even though it is climbing upward in the long term. The real concern is the deep water of oceans, which absorb an overwhelming majority of the world’s human-caused warming, leading to a steady rise in ocean heat content and new records set regularly.
Mann stated that it is wrong to believe the world will soon surpass the threshold because “a concerted attempt to reduce carbon emissions could still prevent crossing it entirely,” Mann explained. “That’s what we need to be focused on.”
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