It won’t be confirmed until January, but it is now almost certain that 2024 will surpass 2023 as the hottest year on record. Even more significantly, the global average temperature is set to show that the planet has warmed by more than 1.5°C since the 19th century – the limit countries agreed to pursue under the Paris Agreement.
But average temperatures are just one way of assessing the rapid changes taking place in the planet’s climate in response to our greenhouse gas emissions. From the oceans to the Amazon, 2024 saw a parade of new climate extremes.
Many of these were captured by the a review of 35 “planetary vital signs” released for the past five years by a group of climate researchers. This year’s analysis, published in October, found that 25 of these climate indicators reached record levels in 2024, prompting the authors to offer this dire assessment: “We are on the brink of an irreversible climate disaster. This is a global emergency beyond any doubt. Much of the very fabric of life on Earth is imperiled.”
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Across the oceans, surface temperatures were at record highs for the first half of the year and remain well above average, although they have fallen below last year’s levels. The amount of heat stored deeper in the oceans, which have absorbed 90 per cent of the excess heat trapped in the atmosphere since the industrial revolution, continued to climb.
In August, a New Scientist cover story explored how all this heat has caused chaos in the oceans, from collapsing fisheries to signs that key ocean currents are changing. The heat has also driven coral bleaching in 77 per cent of the world’s reefs, prompting the US National Oceanic and Atmospheric Administration to declare on record. Adding to stress from heat, the oceans have grown more acidic as they continue to absorb carbon dioxide.
The heat in the oceans has also been a factor behind the extremely low levels of sea ice at both poles. For most of 2024, sea ice extent in the Arctic has remained near the record-low levels set in 2012. The persistently low levels of sea ice since 2007 prompted the National Snow and Ice Data Center in the US to call this Antarctic sea ice, too, has remained near record lows set in 2023 – and briefly surpassed them – reinforcing concerns that southern hemisphere sea ice is also in the midst of a permanent shift.
“2024 teaches us that we have no time to waste: the consequences of climate change are real, they are here today and they are affecting our lives right now,” says at the University of Tasmania in Australia, who has raised alarm about low sea ice extent. “The path to net-zero emissions is not an easy one, but the consequences of delay are becoming frighteningly clear.”
While missing sea ice is bad news for ecosystems and may have other consequences for polar waters, it doesn’t directly affect sea levels. But the ice sheets on land that do contribute to sea level rise are also melting faster than ever. Both the Greenland and Antarctic ice sheets have lost billions of tonnes of mass in 2024, breaking records, according to the State of the Climate report. In September, a six-year investigation of Antarctica’s massive Thwaites glacier projected that its retreat will continue to accelerate, which could eventually trigger the loss of much of the West Antarctic ice sheet and 3.3 metres of sea level rise, although that “doomsday” scenario could take centuries.
Extreme weather has also caused deaths and damage worldwide, from flooding in countries including Ethiopia, Brazil, Spain and Bangladesh to heatwaves In Saudi Arabia, a heatwave killed more than 1100 people making the pilgrimage to Mecca. Along with extreme heat , India saw its longest heatwave on record, with the mercury passing 50°C (122°F) in some places. The US Southwest and Mexico also scorched under a heat dome. Formal attribution analyses found that each of these events was made more likely or was exacerbated by climate change to some extent.
Fuelled by ocean heat, the Atlantic hurricane season roared to a start with Beryl, which rapidly intensified in early July. After an unexpected lull, a series of destructive storms battered the US Gulf Coast one after the other later in the summer. Heavy precipitation from Hurricane Helene caused devastating flooding far inland, stressing water infrastructure and knocking out a major climate data processing centre in North Carolina.
Meanwhile, on the Panama Canal, the problem wasn’t too much water, but a lack of it, as a severe drought exacerbated by climate change led to disruptive traffic jams on the globally important waterway.
The heat also contributed to another extreme year for fire. According to the State of the Climate report, a record 119,000 square kilometres of forest had burned by October across the globe. A parched South America saw especially significant burning, including some of Chile’s deadliest wildfires on record early in the year. Thousands of square kilometres also burned in Brazil’s Pantanal wetlands and the Amazon, releasing more carbon into the atmosphere than any other fire season in at least two decades, . Fires in Canada haven’t been as extreme as in 2023, but with more than 50,000 km2 burned, . The US has seen a much more active season than in 2023, with more than
Alongside changes in the climate itself, greenhouse gas emissions are projected to hit record levels, pushing the . “The thing that keeps me up at night is not knowing how far down this path we will go,” says Doddridge. “Our science tells us that the risks become much, much worse as the world warms. I’d rather not find out just how bad things can get.”
Even if emissions start to fall thanks to the continuing acceleration of clean energy development, further warming is already baked in. Expect more extremes to follow in 2025.
