A recent study entitled Early emergence of anthropogenically forced heat waves in the western United States and Great Lakes was publicized in the Syracuse New York Post Standard under the headline Upstate NY among first to have most heat waves due to climate change. Unfortunately, as Blair King writes “it actually represents a quite excellent example of how science is misrepresented to the public in the climate change debate.”
According to a press release: “Lopez and colleagues used climate models along with historical climate data to project future heat wave patterns. They based their findings on the projection for greenhouse gas emissions this century, known as the RCP8.5 scenario. This assumes high population with modest rates of technological change and energy conservation improvements and is often called the “business as usual” scenario. Lopez said he based the research on this climate scenario because historical greenhouse gas emissions have to date aligned with this projection.”
My concern and that of Blair King is the use of the RCP8.5 scenario. This is a representative concentration pathway that represents a forcing of 8.5 watts per meter squared that is used by climate modelers to represent the worst case atmospheric effect of greenhouse gases by 2100. Essentially this emissions scenario was developed to provide that forcing level.
Larry Kummer looked at the scenario in detail. He notes that “It assumes the fastest population growth (a doubling of Earth’s population to 12 billion), the lowest rate of technology development, slow GDP growth, a massive increase in world poverty, plus high energy use and emissions.” His post explains that RP8.5 assumes population growth at the high end of the current UN forecasts, assumes that the centuries long progress of technology will slow, and assumes no decarbonization of world power sources from new technology (e.g., solar, wind, fission, fusion) or regulations to reduce not just climate change but also air pollution and toxic waste.
Blair King explains that RCP8.5 has a storyline that describes the assumptions of the scenario in easy to understand language. He goes on to explain that the RCP8.5 scenario dates back to 2007 and is characterized by the following:
- Lower trade flows, relatively slow capital stock turnover, and slower technological change;
- Less international cooperation than the A1 or B1 worlds. People, ideas, and capital are less mobile so that technology diffuses more slowly than in the other scenario families;
- International disparities in productivity, and hence income per capita, are largely maintained or increased in absolute terms;
- Development of renewable energy technologies are delayed and are not shared widely between trade blocs;
- Delayed land use improvements for agriculture resulting in increased pollution and increased negative land use emissions until very late in the scenario (close to 2100);
- A rebound in human population demographics resulting in human population of 15 billion in 2100; and
- A 10 fold increase in the use of coal as a power source and a move away from natural gas as an energy source.
Consider those assumptions against what actually has happened since 2007. I am not sure about the status of international disparities in productivity and land use improvements. However, I believe all the other parameters are not following those assumptions. Global trade is at all time highs, renewable technology is freely traded, renewable technology continues to mature and develop, and there is no sign of human population growth accelerating to reach 15 billion. Most importantly, this scenario pre-dates the fracking revolution that has flipped the use of coal and natural gas in the United States by making natural gas so cheap and plentiful. There is no reason to believe that the technology won’t expand elsewhere and markedly reduce any potential increase in the use of coal as a power source.
Lopez states that “he based the research on this climate scenario because historical greenhouse gas emissions have to date aligned with this projection.” He is either ignorant of the substantial change in greenhouse gas emissions observed in the United States or willfully ignored those numbers to misrepresent the science to the public.