The Skeptics Society & Skeptic magazine

According to Steven Koonin, when it comes to climate change, the media, politicians, and other prominent voices have declared that “the science is settled.” Koonin avers that the long game of telephone from research to reports, to the popular media, is corrupted by misunderstanding and misinformation. Koonin says that core questions about the way the climate is responding to our influence, and what the impacts will be remain largely unanswered. Koonin acknowledges that the climate is changing, and claims the why and how aren’t as clear as you’ve probably been led to believe.

Now, one of America’s most distinguished scientists is clearing away the fog to explain what science really says (and doesn’t say) about our changing climate. In Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters, Steven Koonin draws upon his decades of experience — including as a top science advisor to the Obama administration — to provide up-to-date insights and expert perspective free from political agendas.

Michael Shermer challenges Dr. Koonin with many of the most common critiques of his book, to which he responds.

Dr. Steven Koonin is a University Professor at New York University, with appointments in the Stern School of Business, the Tandon School of Engineering, and the Department of Physics. He founded NYU’s Center for Urban Science and Progress, which focuses research and education on the acquisition, integration, and analysis of big data for big cities. He served as Undersecretary for Science in the US Department of Energy under President Obama from 2009 to 2011, where his portfolio included the climate research program and energy technology strategy. He was the lead author of the US Department of Energy’s Strategic Plan (2011) and the inaugural Department of Energy Quadrennial Technology Review (2011). Before joining the government, Dr. Koonin spent five years as Chief Scientist for BP, researching renewable energy options to move the company “beyond petroleum.” For almost thirty years, Dr. Koonin was a professor of theoretical physics at Caltech. He also served for nine years as Caltech’s Vice President and Provost, facilitating the research of more than 300 scientists and engineers and catalyzing the development of the world’s largest optical telescope, as well as research initiatives in computational science, bioengineering, and the biological sciences. In addition to the National Academy of Sciences, Dr. Koonin’s memberships include the American Academy of Arts and Sciences and JASON, the group of scientists who solve technical problems for the US government; he served as JASON’s chair for six years.

Skeptic magazine has published two articles explaining how we know that global warming is real and human caused:

• “How We Know Global Warming is Real” (Dr. Tapio Schneider)
• “How We Know Global Warming is Real and Human Caused” (Donald R. Prothero)

Shermer and Koonin discuss:

• The five basic questions about climate change:
  1. Is the Earth getting warmer?
  2. Is human activity the primary driver of the warming?
  3. How much warmer is it going to get?
  4. What are the effects of the warming?
  5. What should we do about it?
• climate consensus (the 97% figure). Here’s what Dr. Shermer wrote in Scientific American:

  A 2013 study published in Environmental Research Letters by John Cook, Dana Nucitelli, and their colleagues examined 11,944 climate paper abstracts published from 1991 to 2011. Of those papers that stated a position on AGW, 97.1 percent concluded that climate change is real and human caused. What about the three percent? What if they’re right? In a 2015 paper published in the journal of Theoretical and Applied Climatology, Rasmus Benestad, Dana Nucitelli, and their colleagues examined the three percent and found “a number of methodological flaws and a pattern of common mistakes.” That is, instead of the three percent converging to a better explanation than that provided by the 97 percent, they failed to converge to anything. “There is no cohesive, consistent alternative theory to human-caused global warming” Dana Nuccitelli concluded in an August 25, 2015 commentary in The Guardian. “Some blame global warming on the sun, others on orbital cycles of other planets, others on ocean cycles, and so on. There is a 97% expert consensus on a cohesive theory that’s overwhelmingly supported by the scientific evidence, but the 2 — 3% of papers that reject that consensus are all over the map, even contradicting each other. The one thing they seem to have in common is methodological flaws like cherry picking, curve fitting, ignoring inconvenient data, and disregarding known physics.” For example, one skeptical paper attributed climate change to lunar or solar cycles, but to make these models work for the 4,000-year period that the authors considered they had to throw out 6,000 years’ worth of earlier data.

Dr. Shermer then presented Dr. Koonin with critiques of his book, to which he responded. These include Gary Yohe (climate scientist), Marianne Lavelle (reporter, Inside Climate News), and Nadir Jeevanjee (science advisor to C-Change Conversations).

Gary Yohe, Climate Scientist

Yohe, Professor of Economics and Environmental Science, Wesleyan, quoting Koonin and then countering his arguments:

“Heat waves in the US are now no more common than they were in 1900, and that the warmest temperatures in the US have not risen in the past fifty years.” (Italics in the original.) This is a questionable statement depending on the definition of “heat wave”, and so it is really uninformative. Heat waves are poor indicators of heat stress. Whether or not they are becoming more frequent, they have clearly become hotter and longer over the past few decades while populations have grown more vulnerable in large measure because they are, on average, older [Section 19.6.2.1]. Moreover, during these longer extreme heat events, it is nighttime temperatures that are increasing most. As a result, people never get relief from insufferable heat and more of them are at risk of dying.

“The warmest temperatures in the US have not risen in the past fifty years.” According to what measure? Highest annual global averages? Absolutely not. That the planet is has warmed since the industrial revolution is unequivocal with more than 30 percent of that warming having occurred over the last 25 years, and the hottest annual temperatures in that history have followed suit [Section SPM.1].

“Greenland’s ice sheet isn’t shrinking any more rapidly today than it was eighty years ago.” For a risk-based approach to climate discussions about what we “should do,” this statement is irrelevant. It is the future that worries us. Observations from 11 satellite missions monitoring the Arctic and Antarctic show that ice sheets are losing mass six times faster than they were in the 1990s. Is this the beginning of a new trend? Perhaps. The settled state of the science for those who have adopted a risk management approach is that this is a high-risk possibility (huge consequences) that should be taken seriously and examined more completely. This is even more important because, even without those contributions to the historical trend that is accelerating, rising sea levels will continue to exaggerate coastal exposure by dramatically shrinking the return times of all variety of storms [Section 19.6.2.1]; that is, 1-in-100 year storms become 1-in-50 year events, and 1-in-50 year storms become 1-in-10 year events and eventually nearly annual facts of life.

“The net economic impact of human-induced climate change will be minimal through at least the end of this century.” It is unconscionable to make a statement like this, and not just because the adjective “minimal” is not at all informative. It is unsupportable without qualification because aggregate estimates are so woefully incomplete [Section 19.6.3.5]. Nonetheless, Swiss Re recently released a big report on climate change saying that insurance companies are underinsuring against rising climate risks that are rising now and projected to continue to do so over the near term. Despite the uncertainty, they see an imminent source of risk, and are not waiting until projections of the end of the century clear up to respond.

Marianne Lavelle, reporter for Inside Climate News

Lavelle has covered environment, science, law, and business in Washington, D.C. for more than two decades. Here are five statements Koonin makes in Unsettledthat mainstream climate scientists say are misleading, incorrect or undercut by current research:

1. “The warmest temperatures in the US have not risen in the past fifty years.”

   The average annual temperature in the contiguous U.S. has increased from 0.7 degrees to 1.0 degrees Celsius (1.2 to 1.8 degrees Fahrenheit) since the start of the 20th century. The year 2020 was the fifth-warmest year in the 126-year record for the contiguous U.S. And the five warmest years on record have occurred since 2012, NOAA reports. There is a more marked increase in nighttime lows than in daytime highs (the “warmest” temperatures) because of factors like the cooling effect of daytime aerosol pollution and soil moisture evaporation.

2. “Most types of extreme weather events don’t show any significant change — and some such events have actually become less common or severe — even as human influences on the climate grow.”

   There have been statistically significant trends in the number of heavy precipitation events in some regions. Some regions have experienced more intense and longer droughts, while in other places, droughts have become less frequent, less intense, or shorter. Marine heatwaves, periods of extremely high ocean temperatures in specific regions, have become more than 20 times more frequent over the last 40 years due to human activity and the burning of greenhouse gases, according to a 2020 study that relied on satellite measurements of sea surface temperatures.

3. “Humans have had no detectable impact on hurricanes over the past century.”

   In 2020, scientists detected a trend of increasing hurricane intensity since 1979 that is consistent with what models have projected would result from human-driven global warming. Rapid intensification of hurricanes has increased in the Atlantic basin since the 1980s, which federal researchers showed in 2019 is attributable to warming. A 2018 study showed that Hurricane Harvey, which hit Houston the prior year, could not have produced so much rain without human-induced climate change. That same year, a separate study showed that increased stalling of tropical cyclones is a global trend.

4. “Greenland’s ice sheet isn’t shrinking any more rapidly today than it was eighty years ago.”

   Scientific findings indicate with high confidence that the Greenland ice sheet, the world’s second-largest land-based ice reservoir, has lost ice, contributing to sea level rise over the last two decades. And Greenland is on track to lose more ice this century than at any other time in the 12,000-year Holocene, the epoch encompassing human history, scientists reported in 2020. The rate of ice melt in Greenland has varied widely over the decades, and there is evidence of a period of rapid melting in the 1930s that exceeded the rate of today. But the 1930s-era melt affected fewer glaciers, mostly those located entirely on land. Today’s melting involves more glaciers, most of them connected to the sea, with average ice loss more than double that of the earlier period.

5. “The net economic impact of human-induced climate change will be minimal through at least the end of this century.”

   Global warming is very likely to have exacerbated global economic inequality, with the disparities between poor and wealthy countries 25 percent greater than in a world without warming, researchers concluded in 2019. Only a limited number of studies have calculated the aggregate economic impact of climate change, not enough to place confidence in numeric results. But the data indicates with high confidence that climate change will aggravate other stressors, like inadequate housing, food or water supplies, with negative outcomes especially for the poor.

Nadir Jeevanjee, Science Advisor to C-Change Conversations and a research scientist at NOAA’S Geophysical Fluid Dynamics Laboratory, a major U.S. climate-modeling center

But our confidence in these climate changes doesn’t stem solely from the observational record. In large part, it stems from our understanding of basic physics and climate model projections, which show that increased CO2 leads inexorably to a warmer planet, and a warmer planet leads inexorably to melting ice, higher seas, and more extreme weather. Unsettled ignores such projections entirely, arguing that because climate models require empirical adjustments known as “tuning,” and because their quantitative predictions often span a wide range, they cannot be trusted to tell us anything at all. But these models, despite their shortcomings, are skillful in many respects; indeed they have long predicted many aspects of today’s warmer climate, including enhanced warming over land and the arctic. So when these models tell us, unanimously, that heat waves will increase, sea level rise will accelerate, and hurricanes will intensify, we tend to believe them, even if we can’t prove (yet) that the changes we’re currently seeing are definitively due to climate change.

So, should Unsettled be a reminder that climate messaging is not always accurate and sometimes needs to be taken with a grain of salt? Absolutely. But this does not mean the bulk of climate science is suspect. There will always be gaps in the historical data, anomalies to ponder, and models to improve, but by focusing on those elements, Koonin misses the bigger picture: the aggregate of our data, models, and the laws of physics tell us with confidence that significant changes are indeed coming around the bend, and perhaps have already arrived.

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