2024, Hottest Year on Record, Marks ‘Decade of Deadly Heat’

“The top ten hottest years on record have happened in the last ten years, including 2024,” António Guterres said in his New Year message, stressing that humanity has “no time to lose.”

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It is now certain that 2024 will be the hottest year in recorded history, wrapping up a decade of unprecedented heat globally fuelled by human activities.

Scorching, deadly heat has affected many regions of the world this year, with temperatures soaring past 50C in some occasions. Daily global average temperatures broke the record two days in a row, on July 21 and then again on July 22, an event scientists described as “extraordinary.”

The average person experienced 41 additional days of dangerous heat fuelled by human-made climate change in 2024, according to a recent analysis by World Weather Attribution and Climate Central. But for residents of climate-vulnerable regions such as Small Developing Island States, the number of dangerous heat days surpassed 130.

The increase in extreme heat is a direct result of our warming planet, which is driven by greenhouse gases that trap heat in the atmosphere. This raises Earth’s surface temperature, leading to longer and hotter heatwaves.

Atmospheric concentrations of all three major planet-warming greenhouse gases – carbon dioxide (CO2), methane, and nitrous oxide – reached new highs in 2023. Because of these gases’ extremely long durability in the atmosphere, the world is now “committed to rising temperatures for many, many years to come,” Ko Barret, Deputy Secretary-General of the World Meteorological Organization, said last month.

Concentrations of CO2, the principal anthropogenic greenhouse gas in the atmosphere, are now 51% higher than before the onset of the Industrial Revolution. The gas, a by-product of burning fossil fuels, biomass, land-use changes, and industrial processes such as cement production, is responsible for about three-quarters of planet-warming emissions.

Hottest Decade

The relentless growth of greenhouse gas levels has coincided with a steady rise in global temperatures, with the last ten years making up the top ten hottest years on record.

2024 now tops the ranking, beating 2023. It is also the first year above 1.5C, the critical global warming temperature threshold set in the Paris Agreement.

World leaders at the 2015 COP21 climate summit agreed to keep global warming to below 1.5C or “well below 2C” above pre-industrial levels by the end of the century. Beyond this limit, experts warn that critical tipping points will be breached, leading to devastating and potentially irreversible consequences for several vital Earth systems that sustain a hospitable planet.

While the recent heat streak does not signal a permanent breach of the Paris goal, which scientists say is measured over decades, it makes “ambitious climate action … more urgent than ever,” said Burgess.

Addressing the world in his New Year message, UN Secretary-General António Guterres said humanity is on a "road to ruin" and has "no time to lose."

“Today I can officially report that we have just endured a decade of deadly heat," he said. "In 2025, countries must put the world on a safer path by dramatically slashing emissions, and supporting the transition to a renewable future.”