Risks of Irreversible Cryosphere Climate Change
Policy makers and the general public alike now largely accept that the Arctic, Antarctica and many mountain regions already have warmed two-three times faster than the rest of the planet. What is less understood, outside the scientific community, is that the very nature of the cryosphere – regions of snow and ice – carries dynamics that once triggered, in some cases cannot be reversed, even with a return to lower temperatures or CO2 levels.
“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.
Citation: ICCI, 2015. Thresholds and Closing Windows: Risks of Irreversible Cryosphere Climate Change. International Cryosphere Climate Initiative (ICCI), Stockholm, Sweden. 32 pp.
Published: 9 December 2015Download the report
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.”
The 23 scientists, a majority of them IPCC AR5 authors, called on pledges leading to temperatures under two degrees – and preferably, under 1.5 degrees over pre-industrial for the best chance of limiting these risks. Click here to see the “Losses on All Human Timescales” call.
Introduction to Cryosphere Risks (.ppt) *Please note .pptx files cannot be opened in Firefox. You must use “Save As” or Google Chrome to view these presentations.
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.