Comments on the USGCRP Climate and Health Assessment

Global Science Report is a feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.”

On June 8th, the public comment period on the draft report on climate and health from the U.S. Global Change Research Program (USGCRP) closed. Never liking to miss an opportunity to add our two cents’ worth to the conversation, we submitted a set of comments that focused on the weakness of the underlying premise of the report, more so than the specific details (although we did include a sample set of those to show just how pervasive the selective and misuse of science is throughout the report).

Our entire Comments are available here. But, for convenience, here’s the highlight reel. In summary, we found:

What is clear from this report, The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment, and all other similar ones that have come before, is that the USGCRP simply chooses not to accept the science on human health and climate and instead prefers to forward alarming narratives, many based on science fiction rather than actual science. To best serve the public, this report should be withdrawn. By going forward without a major overhaul, its primary service [will] be to misinform and mislead the general public and policymakers alike.

Here we lay out the general problem:

The authors of the USGCRP draft of The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment report have an outstanding imagination for coming up with ways that climate change may negatively impact the health and well-being of Americans, but a profound lack of understanding in the manner in which health and well-being is impacted by climate (including climate change).

In modern American society, we have largely insulated our health and welfare from the climate. The United States has a population of nearly than 320 million people living across a diverse range of climates—a range that is an order of magnitude (or more) larger the projected impacts of human-cause climate change—and yet the health and well-being differences of the population across these diverse climates [are] extremely minimal. Those differences with a direct component of climate associated with them are even smaller. For example, in examining trends and patterns of temperature-related mortality in America, Davis et al. (2004) concluded “The overarching implication of this result indicates that there is no net mortality benefit to one’s place of residence derived from the location’s climate.”

Rather than speculate on how human-caused climate change from greenhouse gas emissions may impact our health and well-being in the future—speculation which is open to influence of preconceived notions, policy preferences, and other matters of personal belief, any or all of which may differ from individual to individual—a more grounded approach is to look across existing climate space and examine the character of the response. In doing so, it is readily obvious that Americans, across all climates, are well-adapted to the prevailing climate (and its inherent weather events, both mild and extreme).

However, this adaptation remains imperfect, as evidenced by the number of Americans still negatively impacted by components of the climate that they live in. Less than perfect, yes, but static, no.

For example, research such as the Davis et al., (2003a, 2003b) shows that while heat waves still lead to elevated daily mortality totals in some cities across the United States (mostly Midwestern and Northeastern cities where heat waves are still relatively uncommon), the sensitivity of urban populations to extreme heat events has been on the decline since at least the mid-1960s (Figure 1). More recent research (e.g., Bobb et al., 2014) shows that these declines have continued. Not only has our adaptive response greatly lowered our sensitivity to extreme elements of climate, but we continue to make improvements going forward.

Figure 1. Annual heat-related mortality rates (excess deaths per standard million population on days in which the decadal-varying threshold apparent temperature (AT) is equaled or exceeded) by city and decade, and long-term trend in summer afternoon AT. Each histogram bar indicates a different decade: from left to right, 1960s–1970s, 1980–1989, and 1990–1998. Decades without histogram bars exhibit no threshold ATs and no heat-related mortality. Decades with gray bars have mortality rates that are statistically significantly different from the decades indicated by black bars. The average excess deaths across all 28 cities is shown at the lower left. AT trends are indicated beneath each city abbreviation (from Davis et al., 2003).

Figure 1. Annual heat-related mortality rates (excess deaths per standard million population on days in which the decadal-varying threshold apparent temperature (AT) is equaled or exceeded) by city and decade, and long-term trend in summer afternoon AT. Each histogram bar indicates a different decade: from left to right, 1960s–1970s, 1980–1989, and 1990–1998. Decades without histogram bars exhibit no threshold ATs and no heat-related mortality. Decades with gray bars have mortality rates that are statistically significantly different from the decades indicated by black bars. The average excess deaths across all 28 cities is shown at the lower left. AT trends are indicated beneath each city abbreviation (from Davis et al., 2003).

There is no tenable reason to think that further improvements will not continue to be achieved and a greater level of adaptation to extreme heat events attained—along with ever less impact on human health and well-being.

Looking beyond extreme temperature impacts on mortality, Goklany (2009), in a major study, found that for the entire collection of extreme weather impacts, mortality has greatly declined over the course of the past several decades, not only in the U.S., but for the globe in general. These findings are extremely relevant to the proper understanding of climate and health in the U.S. Goklany (2009) summarizes:

Current deaths and death rates from extreme weather events for both the U.S. and the globe are, in general, lower than in previous decades. Predictably, annual death rates have declined more rapidly than annual deaths, confirming results from previous studies. This indicates that the total risk of death from such events has actually declined, notwithstanding any increases in the number or intensity of extreme weather events that some claim to have occurred. Globally, as well as for the United States, the aggregate contribution of extreme weather events to the mortality burden is currently minor—on the order of 0.06%.

In the U.S, more lives are lost in an average year to extreme temperatures—both heat and cold—than to more heavily publicized events such as tornados, hurricanes, and floods. According to CDC data, extreme cold, on average, claims more lives than extreme heat, tornados, floods, lightning, and hurricanes combined. In general, mortality and mortality rates from the various categories of extreme events examined here are lower today than in the past. Mortality during the 2000s was lower than in earlier peak periods by 59%–81% for floods, lightning, tornados, and hurricanes, while mortality rates were 72%–94% lower. However, there are no consistent trends for mortality due to floods.

These improvements have occurred despite increases in the populations at risk, in large part because of greater access to the capital and technology necessary to protect against and to cope with adversity in general and extreme weather events in particular. Even if the number of events has increased—and the long-term record is inadequate for ascertaining whether it has—wealth, technology, and human and social capital for the most part have, despite notable exceptions, apparently been of greater importance than any global warming or changes in climatic variability in determining mortality.

Finally, despite population increases, over the long term cumulative mortality from extreme weather events has declined both globally and for the United States, even as total (all-cause) mortality has increased. This indicates that humanity is coping better with extreme weather events than with far more important health and safety problems.

Through our increasing ability to shelter ourselves from the climate, we have greatly reduced the overall impact that the elements of climate have on our overall health/mortality.

The biggest thing missing from virtually all assessments of the impacts of climate change is the very real fact that climate change itself spurs us become better prepared for what it brings. If you ignore this fact (as the USGCRP typically does), your report is overly pessimistic and overly alarming—characteristic features of all USGCRP assessments:

What all of the above tells us can be summed up like this: climate—and for the matter more relevant to the USGCRP Climate and Health Assessment, climate change—begets the human adaptive response.

This is being increasingly being recognized in the scientific literature. For example, Knappenberger et al. (2014), in discussing the response to an increasing frequency of extreme heat events, notes: 

Some portion of this response probably reflects the temporal increase in the frequency of extreme-heat events, an increase that elevates public consciousness and spurs adaptive response. In this manner, climate change itself leads to adaptation. It is insufficient to ignore this effect when compiling and discussing the impacts of climate change. If an increasing frequency of heat events raises public awareness and gives rise to an adaptive response that lowers the population’s relative risk due to extreme heat, this must be properly weighed against any increases in mortality that result from a greater number of mortality-inducing heat events…Our analysis highlights one of the many often overlooked intricacies of the human response to climate change. [emphasis added]

And, unfortunately, the USGCRP and the author team of the Climate and Health Assessment are among those who have completely overlooked this intricacy.

But this does not come as surprising.

We have been through this exercise repeatedly, having submitted voluminous comments on previous USGCRP reports dealing with health, including the first, second, and third National Climate Assessment. While we’ve seen some changes in response to a few of our specific comments, there is never any response to our most general comment, that the overall tone of the USGCRP on the topic is overly pessimistic in light of demonstrable gains in human well-being, even coming in the face of a change climate.

This Climate and Health Assessment is but another in this same mold.

Again, for those wanting more, be sure to check out our set of comments in its entirety.

References:

Bobb, J.F., R.D. Peng, M.L. Bell, and F. Dominici, 2014. Heat-related mortality and adaptation in the United States, Environmental Health Perspectiveshttp://dx.doi.org/10.1289/ehp.1307392

Davis, R.E., P.C. Knappenberger, P.J. Michaels, and W.M. Novicoff, 2003a, Decadal changes in summer mortality in U.S. cities. International Journal of Biometeorology, 47, 166–75.

Davis, R.E., P.C. Knappenberger, P.J. Michaels, and W.M. Novicoff, 2003b, Changing heat-related mortality in the United States. Environmental Health Perspectives111, 1712–1718.

Davis, R.E., P.C. Knappenberger, P.J. Michaels, and W.M. Novicoff, 2004. Seasonality of climate-human mortality relationships in US cities and impacts of climate change. Climate Research, 26, 61-76.

Goklany, I.M., 2009. Deaths and Death Rates from Extreme Weather Events: 1900-2008. Journal of American Physicians and Surgeons, 14, 102-109, http://www.jpands.org/vol14no4/goklany.pdf

Knappenberger, P., Michaels, P., and A. Watts, 2014. Adaptation to extreme heat in Stockholm County, Sweden. Nature Climate Change, 4, 302-303.