A warm tropical ocean slowed Rossby ice loss, Peruvian Huascarán retained methane, and wild C4 grasses surged on extra carbon
A prolonged warming of the tropical warm pool brought Rossby wave snow to Antarctica. Pre-industrial methane measurements from Peruvian Huascarán pointed to tropical emissions, and C4 grasses in southern Africa produced more biomass as carbon dioxide rose.
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Antarctic snow
Heavy snowfall over East Antarctica slowed the continent's total ice loss between 2021 and 2023, and researchers traced the moisture mostly to the mid-latitude Indian Ocean. Unusually persistent warming in the tropical warm pool set off a poleward Rossby wave train that parked a high-pressure anomaly over the area. Multiyear warm pool warming of this kind recurs roughly once a decade in observations; since the resulting precipitation differs from the long-term poleward shift of storm tracks, the mass gain will likely reverse rather than signalling permanent Antarctic moistening.[1]
Huascarán methane
A 2,000-year atmospheric methane series drilled from a Peruvian glacier indicates that the pre-industrial budget was dominated by tropical sources. Most historical methane reconstructions have relied on polar ice cores that could not resolve the exact share of gas arriving from lower latitudes. The 6,768-metre South Peak summit of Nevado Huascarán yielded measurements that, when fed into an atmospheric model, revealed equatorial emissions higher than polar-only estimates had implied.[2]
Nature on C4 grass biomass
Rising carbon dioxide levels fertilised wild C4 grasses in southern Africa, producing a 28 per cent increase in annual aboveground production over three decades. The grasses responded to the changing atmosphere by narrowing their stomata, losing less water while gaining more carbon. Nature reported field observations matching a meta-analysis of CO2 experiments, and researchers attributed the carbon-driven growth to 75.1 grams per square metre a year.[3]
