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IPCC Warns of Tipping Points from Loss of Arctic Snow and Ice


Washington, DC, 25 September 2019—Following the warning from the United Nations Climate Action Summit earlier this week, that climate pledges must increase five-fold to keep the planet from warming more than 1.5ºC, today the IPCC released its Summary for Policymakers for its Special Report on Ocean and Cryosphere in a Changing Climate, describing the accelerating impacts of climate change on ocean, coastal, polar, and mountain ecosystems. 

Most critically the IPCC Report notes the cryosphere is already experiencing a number of globally consequential tipping elements and climate feedback loops that could permanently alter regional and global climate. In the next few decades, these will include mass loss from glaciers, permafrost thaw, and decline in Arctic snow cover and sea ice.

In particular, these cascading feedbacks include the loss of Arctic sea ice, which the IPCC Report notes has decreased extensively in recent years, in both extent and thickness of ice, and that trend will continue unless emissions can be halted. Last week the Arctic sea ice reached its summer minimum, tied for the second-lowest in modern record-keeping. The strong multi-year ice is down to one percent.

Arctic sea ice serves as a great white shield, reflecting heat back into the atmosphere. As it melts it exposes the darker seawater, which absorbs heat instead. This, in turn, accelerates warming in the region and increases the thawing of permafrost—which stores huge reservoirs of carbon dioxide and methane, along with nitrous oxide. The IPCC Report notes “even if global warming is limited to well below 2°C, around 25% of the near-surface (3-4 meter depth) permafrost will thaw by 2100. If greenhouse gas emissions continue to increase strongly, there is a potential that around 70% near-surface permafrost could be lost.” Global permafrost thawing releases its ancient stores of methane, a super climate pollutant more than 80 times more potent at trapping warming than carbon dioxide over the next 20 years.

“Losing the reflective power of Arctic sea ice will lead to warming equivalent to emitting one trillion tons of CO2, which will advance the 2ºC guardrail by 25 years,” said Durwood Zaelke, President of the Institute for Governance & Sustainable Development, quoting from a new study that was published too late to be included in the IPCC Report. (For context, humans have released 2.4 trillion tons of carbon dioxide since pre-industrial times, including from land-use changes.)

“We could lose the remaining Arctic sea ice in 15 years. The bottom line is that it’s not possible to keep the global climate-safe without saving the Arctic sea ice,” he added.

The IPCC Report concludes:

“This assessment of the ocean and cryosphere in a changing climate reveals the benefits of ambitious mitigation and effective adaptation for sustainable development and, conversely, the escalating costs and risks of delayed action. The potential to chart Climate Resilient Development Pathways varies within and among ocean, high mountain, and polar land regions. Realising this potential depends on transformative change. This highlights the urgency of prioritising timely, ambitious, coordinated, and enduring action. (very high confidence)”. (emphasis added)

As for the oceans, the IPCC Report summarizes the impacts of acidification, deoxygenation, and increased warming on marine life, and the implications on global food security and the livelihood of populations that depend on the oceans. Further, continued rising temperatures have exacerbated the melting of ice sheets that leads to increased sea levels, putting people that live in low-lying areas at risk from rising seas as well as extreme storm surge events. The IPCC predicts a rise of up to about 1 meter of sea-level rise by 2100 if emissions aren’t quickly slashed, with the rate of sea-level rise accelerating over time.

The IPCC Special Report on the Ocean and Cryosphere in a Changing Climate is here.

The IPCC Special Report on Global Warming of 1.5ºC is here and its Climate Change and Land Report is here.

An advance chapter of the 2019 UNEP Emissions Gap Report is here.