EPA last week released Climate Change in the United States: Benefits of Global Action. As summarized by the agency’s press release, the 96-page report “compares two future scenarios”:
a future with significant global action on climate change, where global warming [in 2100] has been limited to 2 degrees Celsius (3.6 degrees Fahrenheit), and a future with no action on climate change (where global temperatures rise 9 degrees Fahrenheit). The report then quantifies the differences in health, infrastructure and ecosystem impacts under the two scenarios, producing estimates of the costs of inaction and the benefits of reducing global GHG emissions.
The report has five main sections (health, infrastructure, electricity, water resources, agricultural and forestry, and ecosystems). At the end of each section, EPA cites to an underlying technical study. I may examine one or more of those in a later post. Here I will point out a few tricks EPA uses to make its case.
The core bias that predetermines all the alarming forecasts in EPA’s report is the assumption that, in the reference (“no action”) scenario, global temperatures will increase by 9°F (5°C) between 2010 and 2100 (the red line in the chart below).
Average U.S. temperatures are projected to rise even higher. In the reference scenario, EPA projects a 14ºF increase above present temperatures in the Mountain West and a 12°F increase in the northern regions. In contrast, temperatures rise no more than 4ºF in any state under the “global action” scenario.
Unsurprisingly, in EPA’s assessment, unmitigated warming produces terrible and terrifying climate impacts whereas “global action” reduces such impacts to manageable and non-threatening levels. For example, EPA claims significant global action would reduce U.S. urban heat-related mortality by 93% in 2100, saving approximately 12,000 lives in that year.
How reasonable is it, though, to suppose that average global temperatures in 2100 will be 9°F higher than they are today? Not very.
Over the past 36 years, the lower troposphere (roughly 0-25,000 feet) has warmed at a rate of 0.114°C/decade, according to the latest University of Alabama in Huntsville satellite temperature record (UAH6.0). That translates into another 2.2ºF of warming by 2100, not 9ºF.
Things could change, of course. Nonetheless, there’s no empirical data to back up EPA’s assumption that the warming rate over the next 85 years will increase by 400%.
The 36-year rate is at or below the low end of three of the IPCC’s four global warming projections for the 21st Century, known as representative concentration pathways (RCPs). It’s also smack dab in the middle of the IPCC’s lowest projection of 0.3ºC-1.7ºC, known as RCP2.6, which assumes a 70% reduction in cumulative global GHG emissions between 2010 and 2100. In other words, the warming rate of recent decades is already as low as EPA assumes is possible only through “global action.”
Over the past 18.5 years, a period often described as the warming “pause” or “hiatus,” the UAH V.6 warming rate in the lower troposphere is 0.035ºC/decade, which is near the low end of the RCP2.6 warming range.
So sure, if one starts with errant climate models that increasingly estimate more warming than observed (see chart below), one can easily project scary climate impacts over the next 85 years, and can just as easily deduce big benefits from CO2 reduction policies.
All it proves is that EPA knows how to pick dubious assumptions to get the results it wants.
Nowhere in its 96-page report does EPA mention the “pause” or the growing divergence between models and observations. What then is EPA’s evidence that global warming will add another 9ºF to average global temperatures by century’s end?
EPA uses the Massachusetts Institute of Technology Integrated Global System Model (IGSM) to project future warming. When the model is run with a climate sensitivity of 3ºC (pp. 16-18), the planet warms 9ºF by 2100. Climate sensitivity is generally defined as the equilibrium (final) global mean surface temperature following a doubling of carbon dioxide-equivalent (CO2e) greenhouse gas concentrations.
EPA assumes a climate sensitivity of 3ºC because that was the best estimate in the IPCC’s 2007 Fourth Assessment Report (AR4). EPA notes that AR4 gave a “likely” sensitivity range of 2ºC-4.5ºC. EPA does not mention that the IPCC’s 2013 Fifth Assessment Report (AR5) lowered the bottom end of the “likely” range to 1.5ºC. More importantly, EPA does not mention that a growing number of studies since 2011 have sensitivity ranges and best estimates lower than those in AR4. The chart below shows a partial list comparing the range and average sensitivity of AR5 climate models with recent studies.
Even if the planet were warming as fast as EPA imagines, the agency’s impact projections would still be dubious. For example, EPA estimates that in the “no action” scenario, heat stress will kill an additional 12,000 Americans in 49 cities in 2100 (p. 26). But only about 2,000 U.S. residents die each year from all forms of extreme weather, with about 31% attributed to exposure to extreme heat, according to the Centers for Disease Control. So currently about 620 annual U.S. deaths are heat-related, and U.S. heat-related mortality has been declining, decade-by-decade, since the 1960s, despite rising urban summer air temperatures.
The reason is people aren’t dumb. When hot weather becomes more frequent, people adapt, reducing their vulnerability to heat waves. There is no reason to believe such progress will not continue.
EPA concedes that adaptation “equal to that of Dallas” in all 49 cities could avert thousands of deaths in 2100 (p. 27) but contends that “global action” would save an additional 5,500 lives. However, it is implausible that Dallas in 2015 represents the peak of human adaptive capability — especially if hot weather becomes more prevalent and severe, as EPA imagines.
EPA claims global action would avoid approximately 13,000 premature U.S. deaths in 2050 and 57,000 in 2100 from poor air quality, the theory being that warming will increase ozone and fine particulate matter (PM2.5) air pollution (p. 27). However, it is far from clear that ozone and PM2.5 pose significant health risks at today’s historically low levels. Moreover, as EPA data show, U.S. air pollution emissions and concentrations keep declining despite global warming.
Long before 2100, all significant remaining U.S. air pollution emissions will likely have been eliminated. The impact of warming on U.S. air quality would thus be minimal. Yet EPA claims “global action” will deliver $160 billion and $930 billion in U.S. air quality-related health benefits 2050 and 2100, respectively. How is that possible?
As explained in a text box (p. 25), what EPA actually models is not the impact of projected warming on emission levels reasonably anticipated to occur in 2050 and 2100, but rather the impact of such warming on “present-day levels.” EPA claims that holding present-day levels “fixed” allows the agency “to isolate the climate change-related impact on air quality.” Actually, it allows EPA to grossly inflate the health effects of projected future warming and the alleged benefits of “global action.” The only way to “isolate” the impact of climate change on air quality in 2050 and 2100 is to compare the effects of different warming rates on emissions in those years, not emissions in 2015.
Apparently, EPA is trying to pull a fast one while including just enough info in the fine print to claim that it isn’t.
In its report, EPA does not attempt to calculate the benefits of “global action” using the social cost of carbon (SCC). Nonetheless, MIT economist Robert Pindyck’s criticism of SCC analysis applies with equal force to EPA’s report: It “suggests a level of knowledge and precision that is simply illusory, and can be highly misleading.”
EPA warns that without global GHG mitigation, extreme temperatures will reduce work and wages in “high risk” industries such as agriculture, construction, utilities, and manufacturing. Specifically:
Over 1.8 billion labor hours are projected to be lost in 2100, costing an estimated $170 billion in lost wages. Global GHG mitigation is estimated to save 1.2 billion labor hours and $110 billion in wages in 2100 in the contiguous U.S. that would otherwise be lost due to unmitigated climate change (p. 29).
No economic model can forecast employment levels, labor hours, and prevailing wages in specific industries 85 years into the future. Perhaps all we can say with any confidence is that in 2100, “high risk” industries will be far more productive, automated, and safe than their counterparts today. Nothing is harder to predict than long-term technological change and industrial evolution. EPA’s wages and hours estimates for 2100 are just plain goofy.