Very Low Emissions Could Protect Arctic Summer Sea Ice

Nature Reviews Earth & Environment, 5 March 2024

This review paper provides a clear message: the frequency and length of future sea ice-free periods in the Arctic directly depends on future CO2 emissions. Only the lowest emissions scenario, consistent with 1.5°C offers a possibility of maintaining a perennial sea ice cover. Up to three months of sea ice-free conditions would result with global temperatures at 2°C, extending to four months with ≥2.5°C warming, five months with ≥3.5 °C, and eight months with very high emissions (SSP5-8.5). Briefly exceeding the lower Paris Agreement 1.5°C temperature threshold would still lead to summer sea ice-free periods that occur once every several decades, but these periods could fully disappear with minimal overshoot and sufficient negative emissions that lower CO2 in the atmosphere. An ice-free Arctic Ocean is likely to have multiple deleterious impacts and feedbacks, not only regionally but globally. The study concludes that ice-free conditions can “remain an exception rather than the new normal” if temperatures stay at or return below 1.5°C with only temporary overshoot.

全文 https://www.nature.com/articles/s43017-023-00515-9
通俗易懂的简报： https://www.latimes.com/environment/story/2024-03-05/the-arctic-ocean-could-be-ice-free-within-a-decade