About That Crazy Thing Bernie Sanders Said at the Debate
The money quote on climate change in the first Democratic presidential "debate" was Senator Bernie Sanders's response to moderator Anderson Cooper's question, "what is the greatest national security threat to the United States?"
"The scientific community is telling us," Sanders said, "that if we do not address the global crisis of climate change, transform our energy system away from fossil fuel to sustainable energy, the planet that we're going to be leaving our kids and our grandchildren may well not be habitable" [emphasis added].
Well, no, Senator, "the scientific community" is not telling us that. A few scientists — very few — may be saying something similar (though one would be hard pressed to find it in scholarly publications as opposed to comments to the news media or speeches at rallies), but most aren't saying anything remotely like it, especially those last five words.
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The earth has been through much warmer periods, and during them life of all sorts, plant and animal, thrived. From 1990 to 2013, the IPCC, using computer climate models, posited climate sensitivity (warming effect of added CO2 after feedbacks) in the range of 2–4.5˚C with a best estimate of 3˚, and in 2013 it reduced the lower bound to 1.5˚ and abandoned any "best estimate." Even the upper end of that range would come nowhere near making the earth uninhabitable.
But lately, empirical studies of climate sensitivity (as opposed to the computer models, which have predicted on average twice the warming observed; 95% of which predict more warming than observed, implying that the errors aren't random but driven by bias; and none of which predicted the absence of warming for the last 18 years and 8 months) point to its being far less than what the IPCC has long claimed. (See our review of such studies here, and Judith Curry's ongoing tracking of them here.)
Earlier in the debate Sanders claimed, "the scientific community is virtually unanimous: climate change is real, it is caused by human activity, and we have a moral responsibility to transform our energy system away from fossil fuel to energy efficiency and sustainable energy and leave this planet a habitable planet for our children and our grandchildren."
Again, no, senator. The claims (repeated by President Obama and others ad nauseam) of 97% scientific consensus are bogus. There is perhaps agreement among a little over half of climate scientists that the earth has warmed around 0.8˚ C since 1850 (with ups and downs through the period) and that human activity has contributed significantly to that warming since about 1950.
But even that consensus doesn't extend to assertions that human activity is the main or sole cause, or that we have a moral responsibility to fight it, much less to fight it by transforming our energy system at a cost of trillions of dollars that could be used in other beneficial ways, let alone that climate change is the greatest national security threat facing the United States, and certainly not that our failure to do so could leave the earth uninhabitable.
We can perhaps forgive the candidates for appealing passionately to consensus on climate change. They're politicians. Want to know who won an election? Count votes. Consensus matters in politics.
But consensus doesn't matter in science, particularly not when it's not spontaneous but artificially manufactured through a process of propaganda and intimidation. Want to know how much CO2 warms the earth? Don't count votes — study the data.
Most troubling was the utter failure of any of the candidates to consider the benefits of added CO2 to plant growth, greening the earth and making food more abundant for everyone, people and animals alike, or the impact on the world's poor of the demand to transform our energy economy from abundant, affordable, reliable fossil fuels (which now provide over 85% of all the energy consumed) to diffuse, expensive, unreliable-because-intermittent wind and solar. The consequence, as the petition Forget 'Climate Change', Energy Empowers the Poor points out, would be to slow, stop, or reverse economic growth, trapping billions in abject poverty and the high rates of disease, suffering, and premature death invariably associated with it.
