Illustration: Jim Cooke/Gizmodo

The Heartland Institute, America’s leading peddler of climate change denialism, is back with a new installment in its ongoing misinformation campaign. According to InsideClimate, the Koch brothers-backed think tank recently mailed a second edition of its report on the “unsettled” science of global warming to thousands of American science teachers—much to the horror of educators nationwide.

“I am writing to ask you to consider the possibility that the science [of global warming] in fact is not ‘settled,’” Lennie Jarratt, manager for the Heartland Institute’s Center for Transforming Education, wrote in a cover letter accompanying Why Scientists Disagree About Global Warming, which the nonprofit plans to distribute to 200,000 K-12 and college science educators. According to InsideClimate, 25,000 lucky teachers were hit in the first wave of the Heartland Institute’s assault on logic, reason, and the postal service.

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The report, which can be read here, is a hefty 135 pages of falsehood after distortion after half-truth aimed at sowing doubt on established climate science and the scientific method. I’ve spent a day skimming it so you don’t have to, and collecting rebuttals to a few of its more egregious claims. Because apparently, we really have to be doing this again.

The science of human-caused global warming “is not settled”

The logical fallacies that pervade the entire report start with title and introduction, which reiterate the enduring alternative fact that human-caused global warming is still up for debate. “Extensive survey data show deep disagreement among scientists on scientific issues that must be resolved before the man-made global warming hypothesis can be validated,” the report asserts.

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While scientists disagree on myriad details of how exactly climate change is impacting and will continue to impact our planet (that’s why climate science continues to be an active, vibrant area of research), the notion that the “man-made global warming hypothesis” has not been “validated” is patently false. In fact, if the vast majority of climate scientists agree on one thing at all, it’s that human carbon emissions are causing global average temperatures to rise.

You can read about the scientific consensus on climate change on the websites of agencies staffed by actual climate scientists, like NASA. Or you can take it from the Intergovernmental Panel on Climate Change, which states in its 2014 Summary for Policymakers that anthropogenic (human-caused) greenhouse gas emissions “together with those of other anthropogenic drivers, have been detected throughout the climate system and are extremely likely to have been the dominant cause of the observed warming since the mid-20th century.”

The climate models are garbage

According to the Heartland Institute, global climate models are no better at predicting the future than tea leaves. “GCMs systematically over-estimate the sensitivity of climate to carbon dioxide (CO2), many known forcings and feedbacks are poorly modeled, and modelers exclude forcings and feedbacks that run counter to their mission to find a human influence on climate,” the report brashly claims, adding that models have failed us in the past, that they suffer from “limitations in computing power,” and that they do not incorporate every process imaginable, and are therefore garbage.

It’s true that models are only as good as the data we put in. It’s also true that some forcings (things that push a model one direction or another, like human carbon emissions, or volcanic activity) and feedbacks (outcomes that lead to other outcomes, like vanishing sea ice causing Earth’s surface to become darker, leading it to absorb more of the sun’s energy) are better understood, and better modeled, than others. But just because the models aren’t perfect does not make them useless—quite the opposite.

“They have it completely backward,” Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, told Gizmodo in an email. “No-one uses models blindly—they need to be tested against real-world observations and their predictions have to be evaluated. What Heartland gets wrong is that this has already happened—we have tested GCM predictions and they have not failed but of course they are not perfect either.”

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Today’s global climate models are sophisticated simulations of the Earth based on literal millions of data points collected by satellites, meteorological stations, and ocean buoys. As Schmidt notes, these models are constantly validated by comparing their outcomes with what’s happening in nature. Over time, our models have gotten better at reflecting reality, helping Earth scientists to understand the processes shaping that reality.

“Scientists are constantly working to try to improve these models and reduce uncertainty,” climate scientist Patrick Brown of the Carnegie Institution for Science told Gizmodo. “This is all done openly and honestly in the peer-reviewed literature.”

Schmidt added that there are some consequences of climate change that have occurred faster than our models predicted—like the rapid retreat of Arctic sea ice—“so no one thinks the models are perfect.”

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“The rest of the Heartland statement is just made up,” Schmidt said. “We include all relevant forcings—including natural ones like volcanoes and solar, and anthropogenic effects that cool the climate like aerosols and irrigation....the notion that we are excluding forcings or feedbacks that run against our ‘mission’ is simply nonsense.”

Recent global warming is just “natural variability”

Yes, Earth’s climate has changed and always will be changing and yes, there have been periods in our planet’s history that featured substantially warmer temperatures than today. But using the fact that Earth’s climate has always been changing to argue that modern global warming couldn’t possibly be the result of human carbon emissions is willfully misunderstanding the very evidence being cited. During the Paleocene-Eocene Thermal Maximum some 56 million years ago, the planet warmed some 5 to 9°C (9 to 16°F) over just a few thousand years. The likely cause? A catastrophic release of vast amounts of greenhouse gases—methane, and possibly CO2—into the atmosphere. According to recent research, the rate of human carbon emissions today far exceeds that of the PETM.

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And despite the Heartland Institute’s claim that the impact of the Sun “could be equal to or greater than the effect of CO2 in the atmosphere,” the Sun has been thoroughly ruled out as a driver of modern global warming.

The evidence for climate change impacts is “unreliable”

Why is Arctic sea ice retreating rapidly? Why are sea levels rising, and why does the rate of rise appear to be accelerating? If you subscribe to the Heartland Institute’s interpretation of the scientific method, we can’t possibly know, because, gee whiz, so many factors! “Correlation of, say, a declining number of polar bears and a rising temperature does not establish causation between one and the other, for it is not at all unusual for two things to co-vary in parallel with other forcing factors,” the institute’s tiresome report reads.

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Here Heartland is appropriating a basic scientific axiom—correlation does not equal causation—to basically say we can’t know anything ever, even when other contributing factors have been accounted for and all of the evidence fits a particular hypothesis. In the case of polar bears, a recent peer-reviewed study found that the nineteen Arctic subpopulations have all seen their hunting season shortened because of the retreating sea ice. Volumes of peer-reviewed literature have attributed long-term Arctic sea ice retreat to climate change. A shortened hunting season due to retreating sea ice may not be the only factor influencing polar bear populations right now, but experts agree it’s an important one. Polar bears need to eat a lot, after all, in order to pack on enough fat to survive the long Arctic winter. And what do the world’s polar bear experts have to gain by incorrectly diagnosing the plight of their own research subjects?

Lots of potential consequences of global warming are still being debated, including the degree to which our climate impacts various forms of extreme weather. (Here are some examples.) But if we’re to believe that we cannot reach some conclusions, because we could technically be living in a simulation or whatever, why do science at all? And why, in that case, should we trust Heartland Institute’s conclusion that the scientists have it all wrong? As Carnegie Institution for Science climate scientist Ken Caldeira put it to Gizmodo, “It is ironic that these people, who make a big deal out of climate scientists purportedly claiming to more certainty than is attainable, are themselves making demonstrably false statements without any indication of uncertainty.”

The scientists are just corrupt

Ah, the irony. The Heartland Institute, a fossil fuel interest-backed organization that describes itself as “leading the fight to prevent the implementation of dangerous policy actions to address the supposed risks of global warming,” would like you to believe that the IPCC, an international body comprising hundreds of scientists spanning academia, government and the private sector, is somehow the one feeding you the ideologically-driven drivel.

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The IPCC, “created to find and disseminate research finding a human impact on global climate, is not a credible source,” the Heartland Institute avows. “It is agenda-driven, a political rather than scientific body, and some allege it is corrupt.”

Some, as in, the extremely self-referential Heartland Institute, perhaps?

I can’t muster a better response to the allegations of a global scientific conspiracy than Caldeira did. “Science is a system where people are rewarded for showing that the dominant paradigm is wrong,” he said. “Someone who could demonstrably show that nearly all climate scientists are wrong would likely win a Nobel Prize. Therefore, they believe that nearly every scientist is suppressing evidence that would likely win them a Nobel Prize were they to make this evidence public.”

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“No scientist wants to be someone who history will show to have been fundamentally wrong. Nobody remembers the people who argued against Albert Einstein.”