In a recent Washington Post op-ed, environmental researcher Bjorn Lomborg calls on the next president to “get our priorities straight” on climate change. A tall order. The next president will need the “courage to discard our current feel-good but ineffective solutions.” He or she must also reject the fashionable dogma that climate change is the “defining issue of our time.” I could not agree more.
However, I think Lomborg concedes too much when trying to put the health risks of climate change in perspective. He writes:
Speaking of climate change in catastrophic terms easily makes us ignore bigger problems, including malnutrition, tuberculosis, malaria and corruption. The World Health Organization estimates that climate change since the 1970s causes about 140,000 additional deaths each year, and toward the middle of the century will kill 250,000 people annually, mostly in poor countries. This pales in comparison with much deadlier environmental problems such as indoor air pollution, claiming 4.3 million lives annually, outdoor air pollution killing 3.7 million and lack of water and sanitation killing 760,000. Outside of environment, the problems are even bigger: Poverty arguably kills 18 million each year.
The link Lomborg provides to the estimated “140,000 additional deaths each year” doesn’t clearly identify the source of that estimate. It appears to come from Anthony J. McMichael et al., a chapter on climate change in a World Health Organization (WHO) report. There are serious problems with the analysis.
As the authors acknowledge, estimating the health impacts of climate change is not subject to empirical validation. Therefore, by their own admission, the results of their study cannot be considered scientific:
Empirical observation of the health consequences of long-term climate change, followed by formulation, testing and then modification of hypotheses would therefore require long time series (probably several decades) of careful monitoring. While this process may accord with the canons of empirical science, it would not provide the timely information needed to inform current policy decisions on GHG emission abatement, so as to offset possible health consequences in the future (p. 1547).
So instead of testing hypotheses against data, what did they do? The authors discuss their methodology on pp. 1543-1544. First, they used the United Nations Intergovernmental Panel on Climate Change’s (IPCC) climate model projections of how global warming might affect “exposures to thermal extremes and weather disasters (deaths and injuries associated with floods), the distribution and incidence of malaria, the incidence of diarrhea, and malnutrition (via effects on yields of agricultural crops)” in the year 2100. Then, “Estimates of future effects were interpolated back to give an approximate measure of the effects of the climate change that have occurred since 1990 on the burden of disease in 2000.”
Got that? Based on unverifiable, speculative predictions about climate change impacts in 2100, they purport to determine how climate change affects health today!
Why do the authors trust what IPCC models predict for a century from now? They explain:
The models used by the IPCC have been validated by “back-casting”—that is, testing their ability to explain climate variations that already occurred in the past. In general, the models are able to give good approximations of past patterns only when anthropogenic emissions of [GHG and] non-GHG air pollutants (particulates, dust, oxides of sulfur, etc.) are included along with natural phenomena (IPCC 2001b) (p. 1546).
Well, that’s what the IPCC boasted back in 2001 (Third Assessment Report, Summary for Policymakers, p. 11). Things are less settled these days. IPCC model projections increasingly diverge from reality. Indeed, according to climate scientist John Christy, IPCC model projections are consistent with observed temperature change in the bulk tropical atmosphere only when anthropogenic emissions are not included along with natural phenomena.
Most of the deaths in the WHO estimate for year 2000 are attributed to climate change impacts on malnutrition (77,000 deaths), diarrhea (47,000 deaths), and malaria (27,000) (pp. 1544-1545). That is all very dubious, and not only because the numbers are “interpolated” from hypothetical climate impacts in the unknowable future. As the WHO authors acknowledge, all of the climate change-induced present-day deaths are estimated to occur in developing countries. But since much larger numbers of people in developing countries die from such afflictions each year in “baseline” climate conditions, there is no way to verify which or how many of those deaths are actually due to climate change.
For one thing, neither meteorological nor economic data provide clear confirmation that extreme weather is becoming more frequent or severe. What is more, death and death rates related to extreme weather have declined by 93 percent and 98 percent, respectively, since the 1920s. Try finding a climate change signal in that data!
More fundamentally, as the WHO report tacitly acknowledges, malnutrition, diarrhea, and malaria are essentially diseases of poverty, not of climate. High death rates due to malnutrition, diarrhea, and insect-borne disease are the natural condition of humanity where people lack plentiful, affordable, reliable energy and the associated improvements in technology and per capita income.
The state of the world keeps improving, thanks in large part to wealth creation and technologies supported by fossil fuels. Global death rates due to malaria “declined from 194 per 100,000 in 1900 to 9 per 100,000 in 2012, an overall decline of 95.4 percent,” reports environmental researcher Indur Goklany. He also notes that “between 1990–92 and 2014–16, despite a global population increase of 35 percent (or 1.9 billion), the population suffering chronic hunger decreased by 216 million.” UNICEF reports that “From 2000 to 2015, the total annual number of deaths from diarrhea among children under 5 decreased by more than 50 percent—from over 1.2 million to half a million.”
One is free to guess that progress in averting deaths from malnutrition, malaria, and diarrhea would be even greater absent anthropogenic global warming. However, political and economic factors are so much more important in determining mortality risk from diseases of poverty there is no way to tease a greenhouse “fingerprint” out of the data. So although it’s helpful to note that in UN agency statistics poverty kills 120 times more people than climate change, we should also caution that WHO’s climate change mortality estimate is unverifiable conjecture.
That caveat aside, Lomborg’s op-ed is well worth reading. I believe we agree on the big picture that what developing countries need most is economic growth. Hence, they have more to fear from climate policies that would restrict their access to affordable energy than from climate change itself.