El Niño and global heating pushes water vapour in Earth’s atmosphere to record levels in August — SkimNews
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- Copernicus Climate Change Service recorded 27.35 kg of water vapour per square metre in the atmosphere in August, beating the July 2024 record by 0.04 kg/m² — a difference C3S's Dr Julien Nicolas says is equivalent to roughly 20 trillion additional litres of water in the air.
- Climate scientists attribute the record to global heating (warmer air holds about 7% more water vapour per degree of warming) and the historic El Niño, which raised sea surface temperatures across the tropical oceans and increased evaporation.
- August was also the joint hottest month on the ERA5 dataset (since 1940) and the hottest in NOAA records dating to 1850, a near-perfect correlation with the moisture record.
- Dr Julien Nicolas warned that rising atmospheric water vapour increases the risk of intense rainfall and can intensify storms, since heat is released when vapour condenses into cloud droplets.
- The current El Niño in the tropical Pacific is forecast to be the strongest on record, with provisional Australian analysis finding its record peak ocean temperatures are six times more likely because of global heating.
- Prof Steven Sherwood of the UNSW Climate Change Research Centre noted that high humidity prevents night-time cooling during heatwaves, making it harder for people to recover from extreme hot days once water vapour moves to higher latitudes.
- Dr Kimberley Reid of the University of Melbourne highlighted a feedback loop: water vapour is itself a greenhouse gas, so more atmospheric moisture drives further warming, which draws up still more moisture — with the root cause being CO2 and methane emissions from burning fossil fuels.
Why it matters: Water vapour is itself a greenhouse gas, so the record atmospheric moisture feeds a feedback loop that further amplifies the underlying global heating. With Australian analysis already showing El Niño's peak Pacific temperatures are six times more likely due to human-caused warming, the extra 20 trillion litres of atmospheric water heightens risks of intense rainfall and storm intensification worldwide.
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