Editor's note: The following is a rebuttal to Dr. Daniel Botkin's Oct 26 column on climate change, and his contention that global warming is not being caused by human activities. Collaborating on this response were Dr. John Lemons1, Dr. Owen Hoffman2, Lyndel Meikle3, and Ron Mackie4

Introduction

We have a lifelong dedication to national parks and are concerned about Dr. Daniel Botkin’s recent guest article in National Parks Traveler. Our combined backgrounds as scientists and as National Park Service employees leads us to question Dr. Botkin’s use of outdated information and data not accepted by an overwhelming majority of climate change scientists in his article “Climate is Changing, and Some Parks are Endangered, But Humans Aren’t the Cause.” This was his rebuttal to the report on threats to the parks by staff from the Union of Concerned Scientists. Dr. Botkin’s use of information makes it more difficult for the U.S to develop meaningful responses to human–induced global climate change, including protection of National Park Service lands. Our intended audience is people who are not experts in global climate change but who want solid, verifiable and current wisdom about its human attribution.

The sound counter–rebuttal by staff from the Union of Concerned Scientists ably addressed many of our concerns. Some concerns remain. Our concerns and the evidence we provide in rebuttal to Dr. Botkin’s article are supported by overwhelming scientific conclusions that there is a very high probability that human–induced global climate change, due primarily to fossil fuel use and secondarily to land use changes, is already happening. There are numerous reports from the world’s most authoritative scientific body on global climate change, the Intergovernmental Panel on Climate Change; reports from over 20 nations’ national academies of sciences; several reports from the U.S. National Academies of Sciences; reports from the U.S. Global Change Program; and literally many hundreds of independent scientific studies. Further, every scientific organization in the United States that deals with global climate change agrees with the scientific conclusions mentioned above.

Much of Dr. Botkin’s article focuses on a few arguments that there is no evidence of human–induced global climate change. The evidence he uses to support his views are not accepted by the overwhelming majority of global climate scientists, creating a false impression among people who are not experts in climate change that such scientists are uncertain about whether human–induced global climate change is already occurring and that it will become much more serious and irreversible unless urgent mitigation measures are adopted. A few examples of serious and for all practical purposes irreversible changes are loss of summer north pole sea ice; destabilization of the Antarctic and Greenland ice sheets; significant sea level rise; some regions becoming warmer and others cooler; increases in regional droughts and floods; shifts and losses of food producing regions; increases in various human health diseases; significant losses of biodiversity; and increases in regional wars due to conflicts over dwindling and impacted resources and whose livelihoods people depend. Recent surveys show that about 98 percent of climate scientists believe that human–induced global climate change is occurring. So, if Dr. Botkin wishes to go against the grain of the aforementioned conclusions and scientific consensus, he should present some firm evidence. And this, he failed to do.

For the most part, we limit our discussion and use of evidence to issues Dr. Botkin discusses directly; however, in some sections, including our concluding thoughts, we raise some additional issues because of their importance.

Has the Earth Been Warming?

Dr. Botkin devotes three paragraphs to the Medieval Warm Period followed by mention of the ‘Little Ice Age.’ But, he does not say why he discusses these climate events or their significance to conclusions about human–induced global climate change. Perhaps the reason he discusses these events is to demonstrate that historically there has been natural climate variability.

Scientists know very well about natural climate variability and take it into account when making conclusions about global climate change. However, Dr. Botkin does not mention that the Medieval Warm Period and the ‘Little Ice Age’ were regional to parts of Europe and other areas in northern latitudes, and largely irrelevant to the contemporary issue of human–induced global climate change. Further, Dr. Botkin mentions a single paper by Ross McKitrick, an economist, as the basis for his conclusion that there has been no warming of the earth’s atmosphere during the past few hundred years. McKitrick’s paper has gained no traction in altering the consensus of scientific conclusions about the significance of human–induced global climate change.

Consider some of the conclusions in the recent AR 5 report by the Intergovernmental Panel on Climate Change. One, that human influence on the climate system is unequivocal, and many recent observed changes are unprecedented over decades to millennia with widespread impacts on human and natural systems–the atmosphere and oceans have warmed, the amounts of snow and ice have diminished, and sea level has risen. The changes also are unprecedented with respect to both the amount of change and the rate of change. Two, each of the last three decades has been successively warmer at the earth’s surface than any decade since 1850. The period 1983–2012 was very likely the warmest 30–period of the last 800 years and likely the warmest 30–year period of the past 1400 years. Three, ocean warming dominates increases in energy stored in the climate system with subsequent changes in regions of high salinity where evaporation dominates and in regions of low salinity where precipitation dominates. Parenthetically, because of potential interest to readers of National Parks Traveler, recent estimates of global loss of biodiversity due to human–induced climate change range around 25 percent or more by 2050 -– such loss stemming from both the changes of a human–induced climate system and their rate of change.

Further, Dr. Botkin includes a graph courtesy of John Christy, a meteorologist from Alabama State. The source of the graph is The State of the Climate in 2012; the graph uses mid–troposphere temperature five-year averages. On first consideration, the graph shows that there is no correspondence between the forecasts of general circulation models used in global climate change studies and observed temperature changes since 1980. Dr. Botkin’s conclusion based on the graph is that although atmospheric temperature varies, it does so only a little if at all and, further, models are poor predictors of actual temperature changes.

Dr. Botkin ignores the main conclusion of the State of the Climate Report –- that there is a continuation of warming at the Earth’s surface, sea surface, and surface and deep ocean layers. This is the very report he uses for the data he selected in support of his own conclusions. Further, Christy uses mid–troposphere temperatures as a fundamental indicator of human–induced global climate change despite the fact that legitimacy of using mid–troposphere temperatures is thought to be small, not only by the authors of The State of the Climate in 2012 but by the Intergovernmental Panel on Climate Change and other scientific organization with a focus on the use of temperature indicators for determining human–induced global climate change. 

Frequency of Severe Storms and Extremely Hot Days

Dr. Botkin’s discussion of the frequency of severe storms is problematic; for example, he asserts that a claim of the report by the Union of Concerned Scientists is that the danger of flooding simply stems from the rise of sea–level. But the Union of Concerned Scientists does not make this claim, and neither do the reports by the Intergovernmental Panel on Climate Change, or nations’ academies of sciences. As noted in the AR 5 report by the Intergovernmental Panel on Climate Change, changes in extreme weather and climate events have been observed since about 1950 and linked to human influences, including decreases in cold temperature extremes, increases in warm temperature extremes, increases in extreme high sea level, and increases in the number of heavy precipitation events in a number of regions.

Dr. Botkin presents a graph purportedly showing that the number of 95 F degree temperature readings at U.S. weather stations since 1930 shows no increase on an annual basis of days with temperatures above this level. There are two problems with his use and lack of discussion about the data. First, these data pertain to the U.S.; consequently, the data are regional and not a reliable indicator of the state of the global climate. Second, and more importantly, Dr. Botkin fails to note that in, say, a stationary climate, as the years go by there will be a statistical drop in the number of daily heat records. However, during periods of global warming, as per the conclusions of numerous scientific reports and studies we reference, the frequency of heat records has declined much less than expected in a stationary climate.

Concluding Thoughts

Dr. Botkin’s article ignores several issues relevant to global climate change and its possible effects on national parks and protected areas. We discuss these in no particular order of importance.

First, it ignores the issue of ‘finger printing,’ or data that conclusively demonstrate a human attribution to global climate change. One example is that the ratio of certain carbon isotopes in the atmosphere has been decreasing since the Industrial Revolution. The ratio of carbon–13 to carbon–12 is an example because plants preferentially take up the lighter isotope and, hence, since fossil fuels are comprised of plant matter, their burning decreases the ratio in the atmosphere and this decrease has been observed since the Industrial Revolution. Another example is that empirical evidence shows that the upper troposphere has warmed while the lower stratosphere has cooled and this evidence is entirely consistent with the theory about the observable impacts of increased heat energy from greenhouse gases being trapped in the lower levels of the Earth’s atmosphere. A final example is research that identifies how global climate change is related to the amount of carbon emissions by humans since the late 1800s.

Second, the editor of National Parks Traveler, Kurt Repanshek, makes an inadvertent but potentially confusing comment in his October 28th response to Dr. Botkin’s article, wherein Repanshek states, ‘Antarctic sea ice is at record levels.’ Although this statement is true, the more important considerations are empirical data that show instabilities and declines in the mass of ice in the Antarctic (and Greenland) ice sheets; these instabilities and mass declines prompt concerns about significant rises of sea level.

Third, one of the most disturbing things about Dr. Botkin’s article is that he denies there is even a minor probability that human–induced global climate change exists. We wish to make clear that we believe, consistent with our own work, the numerous studies we have referenced, and the very high scientific consensus we have referenced, that the probability of human–induced global climate change is very high.

But for purposes of argument and certainly germane to protected areas of the National Park Service, let us assume that there might be some chance that human–induced global climate change is occurring, but also a chance it is not. Under conditions of scientific uncertainty, the precautionary principle should be invoked. The United Nations Framework Convention on Climate Change recognizes the precautionary principle; the Convention has been ratified by over 190 nations, including the United States, and the Convention has the force of an international legal treaty.

As many readers of National Parks Traveler know, the precautionary principle states that in matters affecting environmental and human health that are serious and irreversible even if some uncertainties exist about risks or impacts, actions to mitigate them should be taken. In other words, erring in making a conclusion that there is an effect when in fact there is none is more protective than erring by making a conclusion there is no effect when in fact there is. By his denial of any chance that human–induced climate change is occurring, Dr. Botkin rules out use of the precautionary principle and therefore offers a lesser degree of protection to National Park Service lands.

Fourth, scientific conclusions are always open to debate, and independent testing is one of the hallmarks of scientific norms. But are we to believe that a single paper Dr. Botkin mentions from McKitrick, an economist, one from Christy, and Dr. Botkin’s article in National Parks Traveler overthrow the weight of evidence from the numerous scientific reports we have referenced that conclude human–induced global climate change already is here? Within the scientific community the debate about whether human–induced global climate change is occurring is outdated and akin to the question of whether the Earth is flat. Newspapers such as the New York Times have indicated publically that they will no longer publish articles concerned solely with the question: Is global climate change occurring? We are not advocating censorship, but only reiterating that the question and major thrust of Dr. Botkin’s article are outdated and have been settled within the scientific community.

Fifth, National Parks Traveler is not a scientific peer–reviewed journal and we are not advocating that it becomes one. We understand that the purpose of National Parks Traveler is to offer a platform for differing points of view. Yet, because Dr. Botkin made use of some scientific evidence and conclusions, this raises the question of whether some outside review would serve to strengthen articles that rely on empirical evidence and its interpretation.

Sixth and finally, we wish to be clear that we value Kurt’s dedication to the lands the National Park Service tries to protect. He provides a much–needed voice for the parks while not being an employee of the parks. We hope that he will continue to take into consideration the enormous effect stories in National Parks Traveler can have on the public, especially as human–induced global climate change increasingly threatens our National Park Service lands.

References

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Anderegg WRL, Prall JW, Harold J, Schneider SH, 2010, Expert Credibility in Climate Change, Proceedings of the National Academies of Sciences, 107: 12107–12109 (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2901439/) Accessed 15 November 2014

Burns CE, Johnston KM, Schmitz OJ, 2003, Global Climate Change and Mammalian Species Diversity in U.S. National Parks, Proceedings of the National Academy of Sciences of the United States of America, 100: 11474–11477 (http://www.pnas.org/content/100/20/11474.full) Accessed 24 November 2014

Bulletin of the American Meteorological Society, 2012, State of the Climate–2012 (http://www.ncdc.noaa.gov/bams-state-of-the-climate/2012.php) Accessed 15 November 2014

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Harvard School of Public Health, 2014, Climate Change and Biodiversity Loss, in: Biodiversity and Human Health (http://www.chgeharvard.org/topic/climate-change-and-biodiversity-loss) Accessed 26 November 2014

Intergovernmental Panel on Climate Change, 2014, The Fifth Assessment Report, The World Meteorological Organization, Geneva, Switzerland (http://www.ipcc.ch/report/ar5/) Accessed 14 November 2014

Oreskes, N, 2004, Beyond the Ivory Tower: The Scientific Consensus on Climate Change, Science 306: 1686 (http://www.sciencemag.org/content/306/5702/1686.full) Accessed 15 November 2014

Shepherd A and 46 others, A Reconciled Estimate of Ice–Sheet Mass Balance 2012, 338 (6111): 1183-1189, Science (http://www.sciencemag.org/content/338/6111/1183.abstract) Accessed 15 November 2014

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1Professor Emeritus of Biology and Environmental Science, Department of Environmental Studies, University of New England, Biddeford, ME 04005 ([email protected]); 2Dr. Owen Hoffman, President, Oak Ridge Center for Risk Analysis, Oak Ridge, TN 37830; 3Lyndel Meikle, National Park Service, Grant–Kohrs Ranch National Historic Site, Deer Lodge, MT 59722; 4Ron Mackie, Retired National Park Service Ranger. Address all correspondence to Dr. John Lemons.