ACC News Brief
Climate Science Global oceans
Surface winds suggest the tropical belt widened over three decades
What happened
A peer-reviewed observational analysis using an ocean-surface-wind proxy estimated that the tropical belt widened by 2.16 plus or minus 0.50 degrees from 1995 to 2024. Most of the inferred widening appeared in the Northern Hemisphere, with strong regional and seasonal variation and weaker model agreement there than in the Southern Hemisphere.
Why it matters
Movement of large-scale circulation boundaries can reshape long-term water risk, so an apparent Northern Hemisphere model gap deserves attention. The study is ocean-only, relies on a proxy for Hadley-cell edges, and is not a formal attribution analysis; it does not by itself prove greenhouse gases caused the trend or that deserts have already expanded.
What to watch
- Independent confirmation with other circulation proxies and tests of satellite-record homogeneity.
- Attribution studies and regional evidence connecting circulation shifts with precipitation, drought, and land impacts.
Sources & evidence
- Widening of the tropics in global surface-air windsPeer-reviewed Article, Scientific Reports 16 (2026), from Atmospheric and Environmental Research's JANUS Research Group. Initially published March 14, 2026; the publisher page records an April 14, 2026 version of record. Ocean-surface-wind proxy analysis; not a formal attribution study.
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