The Earth has a 50% chance of reaching a warming of 1.5°C within 5 years


Jhe world is approaching the warming threshold that international agreements are trying to prevent, with nearly a 50% chance that the Earth will temporarily reach this temperature within the next five years, teams of meteorologists around the world have predicted.

With continued human-caused climate change, there is a 48% chance that the globe will reach an annual average of 1.5 degrees Celsius (2.7 degrees Fahrenheit) above pre-industrial levels in the late 1800s at least once by 2026, a bright red signal in climate change negotiations and science, a team from 11 different forecasting centers predicted for the World Meteorological Organization on Monday evening.

The chances increase with the thermometer. Last year, the same forecasters put the odds at closer to 40% and ten years ago it was just 10%.

The team, coordinated by the UK Met Office, in its overall five-year outlook, said there was a 93 per cent chance the world would set a record for the hottest year by the end of 2026. They also said there is a 93% chance that the five years from 2022 to 2026 will be the warmest on record. Forecasters also predict that the devastating fire-prone mega-drought in the southwestern United States will continue.

“We are going to see continued warming in line with what is expected with climate change,” said Leon Hermanson, lead scientist at the UK Met Office, who coordinated the report.

These forecasts are global and regional climate predictions on an annual and seasonal timescale based on long-term averages and state-of-the-art computer simulations. They are different from increasingly accurate weather forecasts that predict how hot or humid it will be on a certain day at specific locations.

But even if the world hits that 1.5-degree mark above pre-industrial times — the globe has already warmed about 1.1 degrees (2 degrees Fahrenheit) since the late 1800s — this n is not quite the same as the global threshold first set by international negotiators in the 2015 Paris Agreement. In 2018, a major scientific report by the United Nations predicted dramatic and dangerous effects on people and the world if warming exceeded 1.5 degrees.

The global threshold of 1.5 degrees corresponds to the world warming not for one year, but over a period of 20 or 30 years, several scientists have said. This is not what the report predicts. Meteorologists can’t tell if Earth reaches that average until years, maybe a decade or two, after it actually reaches there, because it’s a long-term average, Hermanson said.

“It’s a warning of what will be just average in a few years,” said Natalie Mahowald, a climatologist at Cornell University, who was not part of the forecast teams.

The prediction makes sense given the world’s already high temperature and an additional tenth of a degree Celsius (nearly two tenths of a degree Fahrenheit) is expected due to human-induced climate change over the next five years, said the climatologist Zeke Hausfather of technology company Stripe and Berkeley Earth, who were not part of the forecast teams. Add to that the likelihood of a strong El Nino – the natural periodic warming of parts of the Pacific that alters the global climate – which could temporarily push up a few more tenths of a degree and the world hits 1.5 degrees.

The world is in the second consecutive year of a La Nina, the opposite of El Nino, which has a slight global cooling effect but is not enough to counter the global warming of heat-trapping gases vomited by the burning coal, oil and natural gas, the scientists said. The five-year forecast indicates that La Nina should end at the end of this year or in 2023.

The fossil fuel greenhouse effect is like putting global temperatures on a rising escalator. El Nino, La Nina and a handful of other natural weather variations are like going up or down steps on that escalator, the scientists said.

On a regional scale, the Arctic will warm again during the winter at a rate three times that of the globe on average. While the American Southwest and Southwestern Europe are expected to be drier than normal over the next five years, wetter than normal conditions are expected for Africa’s often arid Sahel region, the northern Europe, northeastern Brazil and Australia, the report predicts.

The global team has been making these predictions informally for a decade and formally for about five years, with over 90% accuracy, Hermanson said.

NASA chief climatologist Gavin Schmidt said the numbers in this report are “a bit warmer” than those used by the US NASA and the National Oceanic and Atmospheric Administration. He also had doubts about the skill level on long-term regional forecasting.

“Regardless of what is projected here, we will most likely exceed 1.5°C in the next decade, but that does not necessarily mean that we are committed to it in the long term – or that working to reduce further changes is not worth it,” Schmidt said in an email.

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