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Ocean heat and acid share a month as dry air cuts extra typhoon rain

Marine heatwaves and extreme acidification overlapped about 4 times more often than chance in low and mid latitudes from 1982 to 2024. Drier air limits extra typhoon rain. Woodland in Guildford stayed 4.5 degrees Celsius cooler.

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Coral and teal ocean layers meet in a violet zone beneath a distant sparse-rain storm and a shaded woodland coast.

Compound ocean extremes cluster in summer

Luke Gregor and Nicolas Gruber reconstructed the surface ocean from 1982 to 2024 in AGU Advances and flagged an extreme wherever detrended sea surface temperature and hydrogen ion concentration each sat in the top 5 per cent of its own detrended distribution in the OceanSODA-ETHZv1 product, gridded monthly at 1 degree. Across low and mid latitudes those marine heatwaves and extreme acidification episodes coincided about 4 times more often than independent chance allows, and about 4 times more rarely at high latitudes and in the eastern tropical Pacific. Compound events cluster in summer and swing with the El Niño-Southern Oscillation. Most cover on the order of 500,000 square kilometres and last about a month; The Blob in the northeast Pacific and a North Atlantic event in 2023-2024 ran far past that typical month. The authors note that monthly, 1-degree fields cannot resolve short, sharp events and that the product carries no subsurface coverage, so the counts read as a floor.[1]

Drier air holds back extra typhoon rain

Researchers at the University of Hong Kong and Imperial College London report in Nature Geoscience that tropical cyclone rainfall rises far less than thermodynamics alone would predict. They point to a warmer atmosphere that widens the gap to saturation even when relative humidity holds steady, and they name two mechanisms: rain evaporating before it lands, and condensation held back inside the storm. The analysis combines climate simulations, satellite observations and reanalysis. The authors say global climate models do not fully capture some fine-scale processes and that higher-resolution simulations are needed to refine the projections. The brake limits how fast the increase grows; warming still leaves typhoons wetter than they were.[2]

Guildford woodland logged no heat wave days

Sensors placed at seven sites around Guildford between June 2023 and August 2025 recorded woodland 4.5 degrees Celsius cooler during extreme heat and 2.5 degrees cooler at peak summer hours, with grassland and a lakeside close behind. The built up site logged 54 heat wave days; the woodland logged none. The University of Surrey team defined a heat wave day as at least 28 degrees Celsius for 3 consecutive days, and found heat exposure in 19.6 per cent of summer daytime observations at the built up site against 8.7 per cent at a green wall, the highest among the green and blue sites. Results appear in Environment International. Each infrastructure type was represented by a single location, so local conditions may have shaped the numbers.[3]

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References

  1. News sourcePhys.orgOcean heat and acidity extremes overlap about 4 times more often than chance
    Primary paperAGU AdvancesRecent History of Surface Ocean Acidification Extremes That Compound Marine Heatwaves
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  2. News sourcePhys.orgDrier air brakes the extra rain that warming would otherwise add to typhoons↩
  3. News sourcePhys.orgWoodland ran 4.5 degrees Celsius cooler than built-up Guildford during heat extremes↩
Space and explorationEnergy transition and climate

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