临界点与窗口期

不可逆转冻土带气候变化的风险

政策制定者和公众普遍接受，北极、南极和许多山区变暖的速度已经是地球其他地区的两到三倍。在科学界之外，人们对冰冻圈——即冰雪地区的性质——的理解却很少，它的动力学一旦被触发，在某些情况下即使温度或二氧化碳水平恢复到较低水平也无法逆转。.

“Thresholds and Closing Windows: Risks of Irreversible Climate Change” seeks to convey a message from IPCC AR5 and key cryosphere research since then: that at current commitment levels or INDCs, humanity faces very high risk of crossing certain irreversible thresholds in its cryosphere regions – setting into motion changes that cannot be stopped or reversed, in some cases not without a new “Little Ice Age”, and perhaps not even then. The only way to prevent these dynamics from beginning is to make sure temperatures never rise that high.

引用 ICCI，2015. 临界阈值与关闭窗口：不可逆转的冰冻圈气候变化风险。《国际冰冻圈气候倡议》（ICCI），瑞典斯德哥尔摩。32页。.

已出版： 2015年12月9日

DOI: https://doi.org/10.5281/zenodo.18223467

下载报告

In connection with the release of the print version of “Thresholds” at the Paris climate talks on December 9, a group of the Report reviewers and other leading scientists called for greater reductions to avoid crossing these dangerous thresholds in “cryosphere” – snow and ice – regions, taking out an ad in The Guardian newspaper to express their concern. “This can set into motion very long-term changes that cannot be stopped or reversed, even if temperatures later decrease,” they note. “Some changes, such as committed sea-level rise from the great polar ice sheets, cannot be reversed short of a new Ice Age.”

23名科学家，其中大部分是IPCC第五次评估报告的作者，呼吁各国承诺将气温升幅控制在两摄氏度以下，最好是比工业化前水平低1.5摄氏度，以最大程度地降低风险。. Click here to see the “Losses on All Human Timescales” call.

演示文稿

冰冻圈风险介绍（.ppt） *Please note .pptx files cannot be opened in Firefox. You must use “Save As” or Google Chrome to view these presentations.

Anders Levermann – Ice Sheets (large .ppt)

George Kaser – Mountain Glaciers (.pptx) *Please note .pptx files cannot be opened in Firefox. You must use “Save As” or Google Chrome to view these presentations.

Susan Natali – Permafrost (.pptx) *Please note .pptx files cannot be opened in Firefox. You must use “Save As” or Google Chrome to view these presentations.

Dirk Notz – Arctic Sea Ice (.pdf)