Why an immense marine heatwave off the US west coast has alarmed scientists
An immense marine heatwave off the US west coast is raising concerns among scientists due to its ecological and environmental impacts. The heatwave, which has persisted since September 2025, is expected to expand and strengthen, coinciding with the formation of El Niño. This phenomenon could lead to record-breaking temperatures and disrupted marine food chains across the United States.
- ▪The marine heatwave has affected a vast area from Hawaii to British Columbia and southward to Mexico.
- ▪New projections indicate that the heatwave is expected to expand and strengthen in the coming months.
- ▪The persistent heatwave has contributed to extreme temperatures across the United States, with many weather stations setting new all-time records for March.
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| Original publisher | The Guardian — US |
| Canonical URL | https://www.theguardian.com/us-news/2026/may/22/marine-heatwave-west-coast |
| Publication time | Fri, 22 May 2026 13:00:01 GMT |
| Retrieval time | 2026-05-22T13:17:02.303Z |
| Last seen | 2026-05-22T13:17:02.303Z |
| Headline source | Publisher (no WeSearch rewrite) |
| Excerpt source | publisher body |
| Excerpt method | First ~120 words (~800 chars) of extracted publisher body, fair-use limited. |
| Summary | WeSearch · cerebras-chat (WeSearch summarizer) |
| Summary source text | contentText |
| Citation coverage | Summary is a WeSearch-generated derivative; primary citation is the original publisher URL. |
| Cluster | uHl6XyjqljKZ · 2 stories |
| Cluster logic | Grouped by semantic title/content similarity across sources within a rolling window. Same-publisher template collisions are excluded from coverage comparison. |
| Ranking reason | Story pages are not engagement-ranked. Hub feeds use recency, with optional source-diversified chronological ordering (cap consecutive stories per source). No personalized ranking. |
| Publisher visit | Yes — open original |
| Substitutes article? | No — link-out required for full text |
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| Indexing | May the item be indexed (stored, ranked, made findable)? | Allowed |
| Snippet | May a short excerpt of the publisher's text be shown? | Allowed |
| AI summary | May WeSearch generate its own short summary of the article? | Limited |
| Retrieval / RAG | May the content be exposed for third-party retrieval-augmented generation? | Not asserted |
| Model training | May the content be used to train AI models? | Not asserted |
| Commercial reuse | May the content be reused commercially? | Not permitted |
Basis: Derived from the published RSS/Atom feed. Contact: [email protected]. Reviewed: 2026-07-24.
Opening excerpt (first ~120 words) tap to expand
The sun rises behind mountains at dawn in Mexico City on 28 April 2026. Photograph: Yuri Cortéz/AFP/Getty ImagesView image in fullscreenThe sun rises behind mountains at dawn in Mexico City on 28 April 2026. Photograph: Yuri Cortéz/AFP/Getty ImagesWest CoastWhy an immense marine heatwave off the US west coast has alarmed scientistsWhat does a surge in ocean temperatures, compounded with El Niño, bode for the summer?Eric HolthausFri 22 May 2026 09.00 EDTLast modified on Fri 22 May 2026 09.02 EDTSharePrefer the Guardian on GoogleAn enormous marine heatwave off the US west coast is ringing alarm bells among ocean and atmospheric scientists as new data shows its ecological and environmental effects are intensifying.The unusual area of warm water has persisted since peaking in size during…
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