Cryosphere 1.5°

Where Urgency and Ambition Meet – Why Cryosphere Dynamics Must Mean 1.5° Pathways for 2020 NDCs

Reviewed by over 40 IPCC and other cryosphere scientists, this Report combines the findings of the IPCC Special Report on Global Warming of 1.5 ºC and the IPCC Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC).

The cryosphere – snow and ice regions – is amazingly sensitive to small changes in temperature. This principle holds for an ice cube taken from the freezer, or a mountain glacier or great polar ice sheet: once temperature exceeds 0°C/32°F, it melts. And in Earth’s past, the difference between the 1°C above pre-industrial temperatures where we are today, and 2°C has been very different planetary states, including the difference between a few meters of sea-level rise, to well above 20 meters.

The IPCC SR1.5 and SROCC summaries in this Report confirm the physical reality that at some point in the gradient above 1.5°C, processes will be set in motion that cannot be halted or easily reversed, in some cases not even if temperatures return to pre-industrial. This is why policy decisions in the coming years will determine the future state of the Earth for centuries and generations to come. Cryosphere climate change is slow to manifest itself, but once triggered it inevitably forces the Earth’s climate system into a new state, one that most scientists believe has not existed for 65 million years. This future however is neither defined, nor hopeless. Instead, pathways to the needed lower emissions levels not only exist, but were very well-defined in the SR1.5 as physically, technologically, and economically feasible.

Citation: ICCI, 2019. Cryosphere 1.5°: Where Urgency and Ambition Meet – Why Cryosphere Dynamics Must Mean 1.5° Pathways for 2020 NDCs. International Cryosphere Climate Initiative (ICCI), Stockholm, Sweden. 36 pp.

Published: 12 December 2019

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