{
  "id": 3013287,
  "title": "Why Marine Heat Waves and Acidification Strike Together",
  "url": "https://urgent.news/2026/08/24/why-marine-heat-waves-and-acidification-strike-together",
  "topic": "world",
  "section": "World",
  "published": "2026-08-24T12:12:25.000Z",
  "source": {
    "name": "Eos",
    "slug": "eos",
    "url": "https://eos.org/research-spotlights/why-marine-heat-waves-and-acidification-strike-together"
  },
  "original_language": "en",
  "account": "Marine heat waves and extreme ocean acidification are both harmful individually, but their simultaneous occurrence can intensify their impacts. This was vividly demonstrated during the 2013-2015 \"the Blob\" event in the northeastern Pacific, which led to closed fisheries, stranded marine mammals, seabird deaths, and shifts or losses of sea creatures. However, our comprehension of these combined heat-acidity ocean extremes is still rudimentary, with more research concentrated on heat waves than on acidification.\n\nGregor and Gruber, in a study using 43 years of monthly data from 1982 to 2024 on surface ocean temperatures and acidity, analyzed conditions for compound heat-acidity extreme events. They considered these events extreme when both temperature and detrended acidity surpassed their 95th percentiles. Their findings revealed that such events are more frequent than anticipated by chance. In the low to mid-latitudes, they occur approximately four times more frequently than expected by chance, primarily in areas with permanent stratification. In these regions, heat waves tend to make waters more acidic. Compound events are rare in the eastern equatorial Pacific and around the poles, where deep waters upwell to the surface. When marine heat waves strike these upwelling regions, a warm lens atop the water layer hinders the influx of acidic deep waters, resulting in unusually low acidity for the region.\n\nMost compound heat-acidity events in the study period were under 500,000 square kilometers (roughly the size of Spain) and persisted for about a month. However, a few lasted longer, like the Blob in 2015, which lasted over a year and had long-lasting consequences. El Niño and La Niña events significantly influence these compound events, although they seldom coincide with the events' epicenters in the equatorial Pacific. During El Niño, warmer waters create a lens that obstructs upwelling, thereby diminishing the region's typical acidity. Conversely, during La Niña, cold, deep waters richer in acidity upwell, leading to only an acidification extreme. Nonetheless, it is in the neighboring regions where the effects of warming or increased acidity trigger compound extremes. The new findings align with several aspects of earlier research and provide more insights into the temporal patterns and drivers of these events.",
  "summary": "A chemistry tug-of-war between ocean acidity and carbon in warming oceans determines when and where these damaging events strike.",
  "key_points": [
    "Marine heat waves and acidification worsen each other's effects.",
    "2013-2015 Blob event showed closed fisheries and marine mammal deaths.",
    "Compound events more frequent than chance in mid-latitudes."
  ],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}