Atmosphere sets record water vapor level in August — SkimNews
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- Copernicus Climate Change Service (C3S) measured 27.35 kg of water vapor per square meter in the atmosphere during August, exceeding the previous record set in July 2024 by 0.04 kg/m² — a margin equivalent to roughly 20 trillion liters, or about 41 Sydney Harbours' worth of additional water.
- August also ranked as the planet's joint hottest month on C3S's ERA5 dataset (since 1940) and the hottest on NOAA's record going back to 1850, according to Dr. Julien Nicolas, a senior scientist at C3S.
- C3S attributed the vapor surge to two reinforcing drivers: global heating (which lets air hold about 7% more water vapor per degree of warming) and a strengthening El Niño event in the tropical Pacific, which has fueled record sea-surface temperatures and evaporation.
- Dr. Andrew Dessler of Texas A&M University wrote that it was 'unimaginable that any month in the last few thousand years, maybe 100,000 years' had carried more atmospheric water vapor than August.
- Prof. Steven Sherwood of UNSW's Climate Change Research Centre warned that high humidity suppresses nighttime cooling, making it harder for people to recover from extreme daytime heat — a pathway he said drives much of the heat-exposure burden at higher latitudes.
- Dr. Kimberley Reid of the University of Melbourne highlighted water vapor's role as a greenhouse gas: as concentrations rise, the atmosphere warms further and absorbs still more vapor, with fossil-fuel emissions as the root driver of the feedback loop.
Why it matters: A small 0.04 kg/m² margin above last July's record adds enough atmospheric moisture to intensify heatwaves by blocking nighttime cooling and to supercharge rainfall and cyclones, while the vapor itself acts as a greenhouse gas that pushes temperatures — and thus vapor loads — even higher in a self-reinforcing loop now superimposed on a record-strength El Niño.
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