Abrupt Impacts of Climate Change: Anticipating Surprises

From the National Academies’ Committee on Understanding and Monitoring Abrupt Climate Change and Its Impacts, Abrupt Impacts of Climate Change was published in paperback format, and is made available in PDF format on the Academies website. This publication summarizes the current state of knowledge on potential abrupt changes to the ocean, atmosphere, ecosystems, and high latitude areas; explores how to monitor climate change for warnings of abrupt changes and emerging impacts; and identifies key research and monitoring needs.  It considers abrupt changes to the climate system itself and abrupt climate impacts and tipping points in the physical, biological, or human systems that can be triggered by gradual changes in climate.

The report addresses abrupt changes in sea level rise and related coastal impacts; the ocean, specifically the Atlantic Meridional Overturning Circulation; polar ice sheets; ocean chemistry and associated effects of marine ecosystems; abrupt changes in the atmosphere; weather extremes and the links between extreme events and abrupt change. Impacts are categorized by those which are already occurring, have a high probability of occurrence, or are unlikely to occur - distinguishing the more serious threats from the less likely ones. There is also a focus on sudden climate impacts that have the potential to severely affect the physical climate system, natural systems, or human systems – those which often affect multiple interconnected areas of concern.

The findings suggest that abrupt changes that are already underway and of most immediate concern for societal decisions include the disappearance of late-summer Arctic sea ice and increases in extinction rates of marine and terrestrial species.

The Committee contends that action is urgently needed to improve society’s ability to anticipate abrupt climate changes and impacts and calls for action to develop an abrupt change early warning system to help anticipate future abrupt changes and reduce their impacts. The "Abrupt Change Early Warning System" (ACEWS) would be part of an overall risk management strategy, providing required information for hazard identification and risk assessment. In general, an ACEWS system would:

(1) identify and quantify social and natural vulnerabilities and ensure long-term, stable observations of key environmental and economic parameters through enhanced and targeted monitoring;

(2) integrate new knowledge into numerical models for enhanced understanding and predictive capability; and

(3) synthesize new learning and advance the understanding of the Earth system, taking advantage of collaborations and new analysis tools.

The study was sponsored by the National Oceanic and Atmospheric Administration, National Science Foundation, U.S. intelligence community, and the National Academies.  The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council make up the National Academies.  They are private, independent nonprofit institutions that provide science, technology, and health policy advice under a congressional charter granted to NAS in 1863.

Publication Date: December 3, 2013

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