Earth & climate · the experiment
Compare the Pacific's two futures
Same greenhouse gases, two different airs: one polluted, one cleaned up. Four questions, from beginner to expert, on what clean air does to the trade winds and to El Niño.
1 · Read the trade winds' response
Beginner
In 2036–2054, what does cleaner air do to the equatorial Pacific trade winds?
2 · Work out what remains
Without the pollution cuts, the twelve models on average weaken the trade winds' push on the western Pacific by 1.9 mPa (millipascals, the unit of the wind's push) by mid-century. Cleaner air cancels about 70% of that weakening.
Intermediate
How much weakening is left with cleaner air?
3 · Find the hidden link
With three of the models, the authors rerun the experiment with the same sea temperatures imposed in both futures. Asia still gets the extra sunshine, but the strengthening of the trades disappears.
Expert
What does that tell you about how cleaner air acts?
4 · Explain the heat in Brazil
With cleaner air, El Niño's strength shows no detectable change. Yet over north-eastern Brazil, the chance that an El Niño season lands in the hottest third of the temperatures of the future without cuts rises from 0.75 to 0.96.
Expert
How does the article explain this paradox?
Futures compared
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