Climate Change, Heat Waves, and Adaptation

Tuesday, 17 June 2014
146B-C (Washington Convention Center)
Paul C Knappenberger, Cato Institute, Tucson, AZ, United States and Patrick J Michaels, Cato Institute, Washington, DC, United States
One of the most important prospective impacts on public health and welfare resulting from human-caused climate change is a rise in the rate of heat-related mortality from an increase in the intensity and frequency of extreme urban heat events. It is central to the EPA's Endangerment Finding from carbon dioxide and other greenhouse gases. According to the 2007 Supreme Court case Mass. v. EPA, such a finding requires that EPA regulate these emissions, presumably to the point of non-endangerment.

From the EPA's Technical Support Document for the Endangerment Finding:

"Severe heat waves are projected to intensify in magnitude and duration over the portions of the United States where these events already occur, with potential increases in mortality and morbidity, especially among the elderly, young, and frail." [emphasis in original]

While the first part of this statement is likely to be true (if for no other reason than urban growth), the second half is more a hypothesis than a statement of fact. The "potential" only exists in the absence of an adaptive response. In reality, the adaptive response is strong.

A clear example of this can be seen in the heat-related mortality statistics recently reported for the European city of Stockholm, Sweden. In response to a recent study claiming a climate change-related increase in the number of heat waves had led to an increase of 288 heat-related death in Stockholm over the period 1980-2009, we demonstrate that adaptations there have led to a decrease of 2304 deaths during those heat events. The positive effects of adaptation to heat events overwhelmed the negative impact from an increasing in the number of events.

Not only have we found this to be the case in Stockholm, but in major cities all across the United States. Recent complimentary research has confirmed our original findings and also extended them to the point that there is no longer any support for an elevated risk from heat-related mortality in the elderly population in urban areas in the developed world.

These studies undermine the EPA's arguments and highlight an oft-overlooked human response to climate change--that climate change itself can spur an adaptive response that outpaces the negative impacts of the same climate change.