Why Scientists Disagree about Global Warming
Rather than rely exclusively on United Nation’s IPCC for scientific advice, policymakers should seek out advice from independent, nongovernment organizations and scientists who are free of financial and political conflicts of interest.
The summary below is taken from the book's concluding chapter. You can read it for free at the PDF link above, or buy a hard copy from the Heartland Store. A collection of reviews is here, and a page with even more information about the book has been created here.
In 2017, The Heartland Institute is mailing some 200,000 copies of the second edition of this book to K-12 and college science teachers across America. Read the cover letter of that mailing here.
On April 3, 2017, Heartland Institute President Joseph Bast issued a statement in response to a news release issued by Democratic Reps. Raul Grijalva of Arizona, Rep. Eddie Bernice Johnson of Texas, and Rep. Bobby Scott of Virginia which encouraged teachers to throw away the materials with out looking at them.
On April 4, 2017, Heartland Institute President Joseph Bast wrote a follow-up response to the liberal Democrats, which applies to many erroneous criticisms of this mailing.
The most important fact about climate science, often overlooked, is that scientists disagree about the environmental impacts of the combustion of fossil fuels on the global climate. There is no survey or study showing “consensus” on the most important scientific issues, despite frequent claims by advocates to the contrary.
Scientists disagree about the causes and consequences of climate for several reasons. Climate is an interdisciplinary subject requiring insights from many fields. Very few scholars have mastery of more than one or two of these disciplines. Fundamental uncertainties arise from insufficient observational evidence, disagreements over how to interpret data, and how to set the parameters of models. The Intergovernmental Panel on Climate Change (IPCC), created to find and disseminate research finding a human impact on global climate, is not a credible source. It is agenda-driven, a political rather than scientific body, and some allege it is corrupt. Finally, climate scientists, like all humans, can be biased. Origins of bias include careerism, grant-seeking, political views, and confirmation bias.
Probably the only “consensus” among climate scientists is that human activities can have an effect on local climate and that the sum of such local effects could hypothetically rise to the level of an observable global signal. The key questions to be answered, however, are whether the human global signal is large enough to be measured and if it is, does it represent, or is it likely to become, a dangerous change outside the range of natural variability? On these questions, an energetic scientific debate is taking place on the pages of peer-reviewed science journals.
In contradiction of the scientific method, IPCC assumes its implicit hypothesis – that dangerous global warming is resulting, or will result, from human-related greenhouse gas emissions -- is correct and that its only duty is to collect evidence and make plausible arguments in the hypothesis’s favor. It simply ignores the alternative and null hypothesis, amply supported by empirical research, that currently observed changes in global climate indices and the physical environment are the result of natural variability.
The results of the global climate models (GCMs) relied on by IPCC are only as reliable as the data and theories “fed” into them. Most climate scientists agree those data are seriously deficient and IPCC’s estimate for climate sensitivity to CO2 is too high. We estimate a doubling of CO2 from pre-industrial levels (from 280 to 560 ppm) would likely produce a temperature forcing of 3.7 Wm-2 in the lower atmosphere, for about ~1°C of prima facie warming. The recently quiet Sun and extrapolation of solar cycle patterns into the future suggest a planetary cooling may occur over the next few decades.
In a similar fashion, all five of IPCC’s postulates, or assumptions, are readily refuted by real-world observations, and all five of IPCC’s claims relying on circumstantial evidence are refutable. For example, in contrast to IPCC’s alarmism, we find neither the rate nor the magnitude of the reported late twentieth century surface warming (1979–2000) lay outside normal natural variability, nor was it in any way unusual compared to earlier episodes in Earth’s climatic history. In any case, such evidence cannot be invoked to “prove” a hypothesis, but only to disprove one. IPCC has failed to refute the null hypothesis that currently observed changes in global climate indices and the physical environment are the result of natural variability.
Rather than rely exclusively on IPCC for scientific advice, policymakers should seek out advice from independent, nongovernment organizations and scientists who are free of financial and political conflicts of interest. NIPCC’s conclusion, drawn from its extensive review of the scientific evidence, is that any human global climate impact is within the background variability of the natural climate system and is not dangerous.
In the face of such facts, the most prudent climate policy is to prepare for and adapt to extreme climate events and changes regardless of their origin. Adaptive planning for future hazardous climate events and change should be tailored to provide responses to the known rates, magnitudes, and risks of natural change. Once in place, these same plans will provide an adequate response to any human-caused change that may or may not emerge.
Policymakers should resist pressure from lobby groups to silence scientists who question the authority of IPCC to claim to speak for “climate science.” The distinguished British biologist Conrad Waddington wrote in 1941 (Waddington, C.H. 1941. The Scientific Attitude. London, UK: Penguin Books),
It is … important that scientists must be ready for their pet theories to turn out to be wrong. Science as a whole certainly cannot allow its judgment about facts to be distorted by ideas of what ought to be true, or what one may hope to be true (Waddington, 1941).
This prescient statement merits careful examination by those who continue to assert the fashionable belief, in the face of strong empirical evidence to the contrary, that human CO2 emissions are going to cause dangerous global warming.