Today I am giving a presentation at a forum on climate change sponsored by the Reinsurance Association of America. For those who are visiting this weblog as a result of my invitation during my talk, welcome! I am serving on a panel with several distinguished scientists from the reinsurance industry:

Dr. Eberhard Faust Head of Climate Risks, Department of Geo Risks Research Environmental Management, Munich Reinsurance Company AG

Gerry Lemcke, Ph.D. Head, Catastrophe Perils Team, Swiss Re America Corporation

My talk focuses on current scientific understandings related to the attribution of trends in the growth of economic damages related to weather and climate extremes. My basic conclusion is that, despite various claims to the contrary in the media and by advocacy groups, looking back in time, the evidence from climate impacts scientists provides very little support for claims that any significant part of the trend of increasing economic losses is the result of changes in the frequency or intensity of weather or climate extremes. (We discussed this in some detail last year here and here). Below you can find a long list of relevant studies.

This conclusion is for two reasons. First, although extreme events have varied at all time scales in their occurrence and magnitude (and such variations can be seen in the impacts records), and one can present historical records of various lengths that show trends, there has been no secular increase in extreme events around the world over recent decades. This conclusion is well supported by the most recent assessment of Intergovernmental Panel on Climate Change. A second reason is why the influence of extreme events is hard to detect is that the single most important factor responsible for the trend is increasing population and wealth in exposed locations. Any climate signal in the historical record will be difficult to detect, even after adjusting for societal factors, simply because the size of the climate signal is less than the errors in the societal data.

Looking to the future it is important to consider both possible changes in climate and society. All of the analyses that I am aware of all suggest that societal factors will continue to dominate climate factors, probably overwhelmingly so. We should therefore expect weather and climate-related damage to increase dramatically in future years and decades. This increase will be insensitive to the amount of emissions reductions that might be achieved (either realistically or unrealistically) over coming years and decades. It does not make sense to attempt to modulate future extreme events, and by extension their impacts, with energy policies (although there are other good reasons for thinking about energy policy and CO2 emissions.) Reduction of the economic and other human impacts of weather and climate will be most effective when focused on the societal conditions that lead to ever growing vulnerability.

It is of course important to recognize that science is always a work in progress and new experience or studies might give good reasons for a change in expectations.

For further reading:

Downton, M., J. Z. B. Miller and R. A. Pielke, Jr., 2005. Reanalysis of U.S. National Weather Service Flood Loss Database, Natural Hazards Review, 6:13-22. (PDF)

Pielke, Jr., R. A. and D. Sarewitz, 2005. Bringing Society back into the Climate Debate, Population and Environment, Volume 26, Number 3, pp. 255-268. (PDF)

Sarewitz, D., and R.A. Pielke, Jr., 2005. Rising Tide, The New Republic, January 6. (PDF)

Pielke, Jr., R. A., J. Rubiera, C. Landsea, M. Fernandez, and R.A. Klein, 2003: Hurricane Vulnerability in Latin America and the Caribbean, Natural Hazards Review, 4:101-114. (PDF)

Downton, M. and R.A. Pielke, Jr., 2001: Discretion Without Accountability: Politics, Flood Damage, and Climate, Natural Hazards Review, 2(4):157-166. (PDF)

Changnon, S., R. A. Pielke, Jr., D. Changnon, D., R. T. Sylves, and R. Pulwarty, 2000: Human Factors Explain the Increased Losses from Weather and Climate Extremes. Bulletin of the American Meteorological Society, 81(3), 437-442. (PDF)

Pielke, Jr., R.A., and M.W. Downton, 2000: Precipitation and Damaging Floods: Trends in the United States, 1932-97. Journal of Climate, 13(20), 3625-3637. (PDF)

Pielke, Jr., R. A., R.A. Klein, and D. Sarewitz, 2000: Turning the Big Knob: Energy Policy as a Means to Reduce Weather Impacts. Energy and Environment, Vol. 11, No. 3, 255-276. (PDF)

Landsea, C. L., R. A. Pielke, Jr., A. Mestas-Nuez, and J. Knaff, 1999: Atlantic Basin Hurricanes: Indicies of Climate Changes. Climate Change, 42, 89-129. (PDF)

Pielke, Jr., R. A., and M. Downton, 1999: U.S. Trends in Streamflow and Precipitation: Using Societal Impact Data to Address an Apparent Paradox. Bulletin of the American Meteorological Society, 80(7), 1435-1436. (PDF)

Pielke, Jr., R.A., and C.W. Landsea, 1999: La Nia, El Nio, and Atlantic Hurricane Damages in the United States. Bulletin of the American Meteorological Society, 80, 10, 2027-2033. (PDF)

Pielke, Jr., R. A., and C. W. Landsea, 1998: Normalized Hurricane Damages in the United States: 1925-95. Weather and Forecasting, American Meteorological Society, Vol. 13, 621-631. (PDF)