In a remarkably candid essay in the March issue of Nature, one of the world’s top climate scientists raised the alarming possibility that global warming is outpacing experts’ ability to predict what will happen.
“The 2023 temperature anomaly came out of nowhere, revealing an unprecedented knowledge gap, perhaps for the first time in about 40 years, when satellite data began offering modelers an unprecedented, real-time view of Earth’s climate system,” wrote Gavin Schmidt, a British scientist and director of the Nasa Goddard Institute for Space Studies in New York.
If this anomaly fails to stabilize by August, it could mean “a warming planet is already fundamentally changing how the climate system works, much earlier than scientists expected.”
Many in the science and environmental communities read these words with alarm. Was the jump in temperatures over the past 13 months, which has exceeded experts’ global warming predictions, a sign of a systemic shift, or merely a temporary anomaly? If the world was warming even faster than scientists had thought, and seemingly years ahead of predictions, would that mean that even more crucial decades of action have been lost?
Now that August is here, Schmidt is a fraction less alarmed. He said the situation remains unclear, but that broader global warming trends are starting to move back in the direction of predictions. “What I think now is that we’re not that far off from expectations. If we keep this up for the next few months, we can say that what happened in late 2023 was more ‘blippish’ than systematic. But it’s too early to say,” he said. “I’m a little less worried, but I’m still humbled that we can’t explain it.”
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In an exclusive interview with the Guardian, Schmidt said that records were broken by a surprising margin last year. He predicts that 2024 will likely also see a new high, although the trend may be closer to expectations.
Looking back at the most extreme months of heat in the second half of 2023 and early 2024, when previous records were sometimes broken by more than 0.2 degrees Celsius, a huge anomaly, he said scientists were still baffled: “We don’t have a quantitative explanation for even half of it. That’s quite humbling.”
He added: “We should have better answers now. Climate modelling as an enterprise is not meant to be super reactive. It’s a slow, long process where people around the world volunteer their time. We haven’t got our act together on this question yet.”
This is not to question the underlying science of global warming. Over 99.9% of climatologists agree that it is caused by human burning of gas, oil, coal and forests.
That alone sets alarming new temperature records every year, as the world experienced last month with two consecutive days of heat higher than ever recorded by humans, and likely higher than ever in more than 120,000 years.
This is causing devastation across an even larger part of the world through increasing wildfires, droughts, floods, loss of sea ice and other extreme weather phenomena.
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The worsening trend will continue until fossil fuels are retired. “As climate change continues, it gets warmer every decade, the impacts are greater, the consequences are greater,” Schmidt said. “So in that sense, we are already in uncharted territory with respect to climate, and with every decade we are going further down a sidetrack.”
The recent El Nino has added to the global heat stress. Scientists have also pointed to the effects of the January 2022 Hunga Tonga-Hunga Ha’apai volcanic eruption in Tonga, increased solar activity in the run-up to a predicted solar maximum, and pollution controls that reduced the amount of cooling sulfur dioxide particles. But Schmidt said none of these possible causes were sufficient to explain the temperature rise.
Schmidt said he hoped a clearer picture would emerge by the time the American Geophysical Union meets in December, when many of the world’s top Earth system scientists gather in New Orleans, Louisiana.
One of the most troubling theories to emerge is that Earth is losing its albedo, the planet’s ability to reflect heat back into space. This is largely due to a reduction in the amount of white ice in the Arctic, Antarctic, and mountain glaciers. Peter Cox, a professor at the University of Exeter, noted on X that this is “contributing massively to the acceleration of global warming.” It would also suggest that the recent data isn’t just a strange coincidence.
On July 29, the total extent of sea ice was at a record low for that date, nearly 4 million square kilometers (1.5 million square miles) — an area larger than India — below the 1981-2010 average, said Zackary Labe, a climate scientist with the U.S. National Oceanic and Atmospheric Administration.
It is still melting rapidly as temperatures in some parts of Antarctica recently reached 24 degrees above average for the time of year, in the middle of the Australian winter.
United Nations Secretary-General António Guterres recently warned that “the Earth is becoming hotter and more dangerous for everyone, everywhere”.
Related: Unprecedented number of global heat records broken this year
He pointed out that scorching temperatures during the Hajj in Saudi Arabia killed 1,300 pilgrims, closed tourist attractions in European cities and closed schools in Asia and Africa.
Temperatures above 50 degrees Celsius were previously rare and limited to two or three global hotspots. However, the World Meteorological Organization noted that at least 10 countries reported such levels of scorching heat in the past year: the US, Mexico, Morocco, Algeria, Saudi Arabia, Kuwait, Iran, Pakistan, India and China.
In Iran, the heat index – a measure of humidity – has reached dangerously close to 60 degrees Celsius, far above levels considered safe for humans.
Heatwaves are now commonplace around the world, killing the most vulnerable, exacerbating inequality and threatening the well-being of future generations. UNICEF calculates that a quarter of the world’s children are already exposed to frequent heatwaves, and that this will rise to almost 100% by mid-century.
The pace of change is disorienting. Schmidt says there is a 72 percent chance that 2024 will break last year’s heat record. The odds will increase even more if there is no cooling La Niña in December.
While some argue that the world will soon pass the lower Paris limit of 1.5 degrees of warming above the pre-industrial average, Schmidt says the more important goal should be to phase out carbon emissions as quickly as possible: “What should motivate people is that with every tenth of a degree of warming, the impact will increase. That’s the fundamental equation. It doesn’t matter where we are now, but we have to get to net zero. The faster we do that, the happier we’ll be.”
At times, he admitted that his work got him into trouble. As a scientist, he wants his predictions about global warming to be correct, but as a human being, he would rather they were overestimated.
“We would all rather be wrong than right,” he says. “That’s the one thing skeptics don’t understand.”