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Highlights d Microplastics were found in snow and stream water samples on Mt. Everest d The highest microplastics were discovered in a sample from 8,440 m.a.s.l. d Most microplastics were polyester fibers, likely from clothing and equipment d Technological advances could minimize microplastic pollution from exploration

Changes in ocean circulation are thought to have contributed to lowering glacial atmospheric CO 2 levels by enhancing deep ocean sequestration of carbon that was returned to the atmosphere during glacial terminations. High-resolution benthic foraminiferal δ 13 C and δ 18 O records from a depth transect of cores in the Southwest Pacific Ocean presented here provide evidence that both wind-and thermohaline-driven circulation drove CO 2 from the ocean during the last deglaciation. Shallow geochemical stratification in the glacial Southern Ocean was followed by a short pulse of rapid δ 13 C enrichment to intermediate water depths during Heinrich Stadial 1, indicative of betterventilated intermediate waters co-occurring with documented wind-driven upwelling in the Southern Ocean. Intermediate depth  13 C enrichment paused at the start of the Antarctic Cold Reversal (~14.7 ka), implying a brief shallow restratification, while deeper layers were progressively flushed of δ 13 C-depleted and δ 18 O-enriched waters, likely caused by the increasing influence of deep waters sourced from the North Atlantic. The coincidence of atmospheric CO 2 increases with these geochemical shifts in both shallow and deep cores suggests that shifts in both atmospheric and oceanic circulation contributed to the deglacial rise of CO 2 .

Capsule We installed the world’s highest weather stations on Mount Everest, offering new insights into water resources under climate change, and potentially improving climber safety.