We finally have an explanation for 2023’s record-breaking temperatures

A decline in low-lying cloud cover means Earth is absorbing more solar radiation, which could explain 0.2°C of missing heat scientists have been struggling to account for

By Madeleine Cuff

5 December 2024

There was a sharp fall in the number of low-lying clouds in 2023

Busà Photography/Getty Images

Changes in cloud cover may account for why global temperatures for the past two years have exceeded the predictions of climate models.

2023 and 2024 saw temperature records repeatedly smashed, with both years now showing average temperatures around 1.5°C above the pre-industrial level. Climate change plus an El Niño weather pattern are partly to blame, but neither factor fully explains the extraordinary warmth.

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Now, researchers believe the answer lies in a sharp drop in low-lying cloud cover in 2023. This change reduced Earth’s albedo – the planet’s ability to reflect solar radiation back into space – causing an increase in temperatures.

Earth’s albedo has been declining since the 1970s, largely due to the melting of polar ice caps, which help to bounce sunlight back into space. But analysis of satellite data by Helge Goessling at the Alfred Wegener Institute in Germany and his colleagues revealed that 2023’s planetary albedo hit a record low.

Goessling and his colleagues then used a combination of weather observations and modelling to understand the causes of this drop, and found there had been a sharp fall in the number of low-lying clouds in 2023. The change was particularly pronounced in the Atlantic Ocean, which experienced some of the most unusual temperature extremes in 2023.