Abrupt Climate Change

Traditionally, most climate change analyses have assumed any impacts would emerge gradually. But in recent years, evidence has grown that the climate system can exhibit abrupt changes that emerge rapidly once the system passes some threshold or tipping point. Including the potential for such abrupt changes in policy analyses of climate change can be difficult, however, for at least two reasons. First, the resulting discontinuities can make policy models more difficult to solve. Second, the likelihood of any abrupt change can be difficult to estimate.

In this project we have been advancing and using robust decisionmaking methods to better address these issues. In particular, we have examined the ability alternative observation systems to provide actionable warning of any oncoming change in the North Atlantic meridional overturning circulation, evaluated the costs and benefits of early action and optimal risk reduction strategies in the face of uncertain climate thresholds, and estimated the benefits and risks of carbon sequestration technologies as a response to potential abrupt climate changes.

This research has advanced the ability to address this type of uncertainty in climate change policy and has provided some valuable policy insights. In addition, we have used the results of these analyses to support our judgment and decision making laboratory experiments that assess how individuals respond to different characterizations of deep uncertainty.

Published Research

Managing the Risk of Uncertain Threshold Responses: Comparison of Robust, Optimum, and Precautionary Approaches

Lempert, Robert J. and Myles T. Collins

Risk Assessment, Vol 27, No 4, 2007, p. 1009-1026.

Early Detection of Changes in the North Atlantic Meridional Overturning Circulation: Implications for the Design of Ocean Observation Systems — 2007

Keller, K., C. Deutsch, M. G. Hall and D. F. Bradford

Journal of Climate, Volume 20, Issue 2, January 2007, pp. 145-157.

Economically Optimal Risk Reduction Strategies in the Face of Uncertain Climate Thresholds — 2007

McInerney, D. and K. Keller

Climate Change, Published online, January 2007.

Submitted or In Press

Detecting Potential Changes in the Meridional Overturning Circulation at 26°N in the Atlantic — 2007

Baehr, J., K. Keller, and J. Marotzke

Climate Change

The Dynamics of Learning about a Climate Threshold — 2007

Keller, K. and D. McInerney

Climate Dynamics

Global Optimization of an Observing System Design for the North Atlantic Meridional Overturning Circulation — 2007

Baehr, J., D. McInerney, K. Keller, and J. Marotzke

Journal of Atmospheric and Oceanic Technology

Managing the Risks of Climate Thresholds: Uncertainties and Needed Information

Keller, K., G. Yohe, and M. Schlesinger

Climatic Change

Oxygen Observations Improve the Detection Capabilities of an Ocean Observation Array — 2007

Brennan, C., R. Matear, and K. Keller

Journal of Geophysical Research – Oceans

The Regrets of Procrastination in Climate Policy — 2007

Keller, K., A. Robinson, D. F. Bradford, and M. Oppenheimer

Environmental Research Letters

Robust Strategies in the Face of Uncertain Climate Thresholds — 2007

McInerney, D., R. Lempert, and K. Keller

Risk Analysis

What is the Economic Value of Information About Uncertain Climate Thresholds?

K. Keller, S.-R. Kim, J. Baehr, D. F. Bradford, and M. Oppenheimer

Chapter in Integrated Assessment, The State of the Art