格陵兰岛因今天的排放和温度已“锁定”海平面上升一英尺：但快速减排可避免进一步损失

Nature Climate Change, 29 August 2022

New research suggests that the Greenland Ice Sheet is already committed to lose 3.3% of its ice, even if the world stopped emitting greenhouse gasses today; this ice loss will trigger nearly one foot (27 cm) of global sea-level rise. While the study does not specify a time frame for this amount of sea-level rise, authors suggest that especially with continued emissions, much of this loss will occur by 2100. Authors used the past two decades of accelerated ice loss to predict future ice sheet behavior. When they based forecasts on a year when massive Greenland melt occurred, such as 2012, they found that Greenland may be committed to produce more than 2.5 feet (nearly 80cm) of sea-level rise over coming centuries already at today’s climate.

Greenland’s vulnerability to long-term ice loss increases as global temperatures rise. The intrusion of warm ocean waters in Greenland’s fjords erodes the base of glaciers, releasing more icebergs into the ocean. Surface melt however becomes more important as the point where snow and ice accumulates each year moves higher up the ice sheet, which is 3 km in altitude; with rain rather than snow falling for greater periods during the year and at higher altitudes (and rain was recorded at the highest research station for the first time in August 2021). These factors prevent the ice sheet from regaining its former size after each melt season, thereby committing it to a certain amount of irreversible ice loss.

Sea-level rise increases coastal erosion, flooding, and devastating storm surges on a global scale. Authors underscore the importance of urgent action to reduce emissions. Although the world is already committed to more sea-level rise from Greenland than previously thought, reducing emissions will have a huge positive impact on the ability of low-lying island nations and coastal communities to adapt. Curbing global temperatures to uphold the 1.5°C limit of the Paris Agreement, the authors conclude, will minimize future destructive sea-level rise; and give nations across the world time to implement necessary adaptation strategies to protect vulnerable populations.

https://www.nature.com/articles/s41558-022-01441-2