Last year, CNN announced: “Oceans are warming at the same rate as if five Hiroshima bombs were dropped in every second.” True. However: “The earth absorbs sunlight (and radiates an equal amount of heat energy) equivalent to two thousand Hiroshima bombs per second.” That sentence is from “Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters,” by physicist Steven E. Koonin, formerly of Caltech, now at New York University after serving as the senior scientist in President Barack Obama’s Energy Department and working on alternative energy for BP. His points are exclusively from the relevant scientific literature.
Because unusual weather events are routinely reported as consequences of climate change, Koonin warns: “Climate is not weather. Rather, it’s the average of weather over decades.” Of course the climate is changing (it never has not been in Earth’s 4.5 billion years), the carbon footprints of the planet’s 8 billion people affect the climate, and the effects should be mitigated by incentives for behavioral changes and by physical adaptations.
Human activities account for almost all of the increased atmospheric carbon dioxide concentration, but science has limited ability to disentangle human and natural influences on climate changes in, for example, the Little Ice Age (about 1450-1850) or the global cooling of 1940-1980. Although Koonin cites U.N. reports when saying “human influences currently amount to only 1 percent of the energy that flows through the climate system,” media “reports” say hurricanes are increasing in numbers and intensity. Koonin says “humans have had no detectable impact on hurricanes during the past century.” Improved weather radar detects even weak tornadoes, hence the increase in reported ones. But, says Koonin, data from the National Oceanic and Atmospheric Administration show the number of significant ones has changed negligibly, and the strongest kind have become less frequent.
Sea levels, currently rising a few millimeters a year, have been rising for 20,000 years. Koonin cites recent research that the rate of rise ascribable to melting glaciers has “declined slightly since 1900 and is the same now as it was 50 years ago.” The melting of the Greenland and Antarctic ice sheets contributes no more to rising sea levels in recent decades than it did 70 years ago. The average warmest temperature across the United States has hardly changed since 1960 and is about what it was in 1900.
A scandalous 2019 Foreign Affairs article by the director-general of the World Health Organization asserted: “Climate Change Is Already Killing Us.” Says Koonin, “Astoundingly, the article conflates deaths due to ambient and household air pollution (which cause … about one-eighth of total deaths from all causes) with deaths due to human-induced climate change.” The WHO says indoor air pollution in poor countries, mostly the result of cooking with wood and animal and crop waste, is the world’s most serious environmental problem. This is, however, the result not of climate change but of poverty, which will become more intractable if climate-change policies make energy more expensive by making fossil fuels less accessible.
New coal-fired power plants in China and India will double and triple those nations' emissions, respectively. There are, Koonin says, five times more people “developing” than “developed,” and in this century cumulative carbon dioxide emissions from developing nations will be larger than from developed nations. Every 10 percent reduction that the developed world makes (“a reduction it has barely managed in 15 years”) will offset less than four years of emissions from growth in the developing world.
Koonin notes (as instant media analyses of the 4,000 pages might not) that this week’s U.N. study expresses low confidence in most reported trends in hurricane properties over a century, is uncertain whether there is more than natural variability in Atlantic hurricanes and calls its extreme emissions scenarios unlikely. Some of its plausible emissions scenarios project 1.5 to 2.7 degrees Celsius warming by 2100.
By then, however, global gross domestic product, which grows by a larger multiple than population, will mean a much-increased per capita global wealth. A previous U.N. report said that a large global temperature rise of 3 degrees Celsius might negatively impact the global economy as much as 3 percent by 2100. Koonin says: Assuming, conservatively, 2 percent annual growth, the world economy, today about $80 trillion, would grow to about $400 trillion in 2100; climate impacts would reduce that to $388 trillion. Not quite an “existential” threat.