Courtesy of Barack Obama, where it has been echoed throughout the administration, including this John Kerry speech in Indonesia:

97 percent of climate scientists have confirmed that climate change is happening and that human activity is responsible…And they agree that, if we continue to go down the same path that we are going down today, the world as we know it will change – and it will change dramatically for the worse.

The “97% of scientists” statement has become so ubiquitous that it follows the aphorism, “if you repeat something often enough it becomes true.”  It has been repeated ad nauseam, to the point where in a recent exchange with Ted Cruz, the Sierra Club president was reduced to a broken record citing this statistic and nothing else.  The implication is if you disagree with virtually all the scientists, you’re an idiot, so throwing this statistic out is meant to “end the debate”.  However, if we’re so enamored with science and reason, should we not go a little deeper and examine this statistic?  What do 97% of scientists actually agree on?  That the climate changes?  That we have a tiny impact?  A moderate impact?  A huge impact?  That the result will be good?  Dangerous?  So dangerous that we must stop using fossil fuels?  These are never explained by the perpetrators of this meme, so what’s the real truth and context behind the 97% statistic?

The Study

In May 2013, John Cook published a study on his website.  The study took 12,000 academic papers on climate from 1991-2011 and analyzed their abstracts.  About 2/3’s of the papers were found to have no stated position on climate change, but from the 1/3 which did, the study claims 97.1% agreed with the position that it’s real, and man made.  However, when looking at the study more closely, this becomes much more dubious, as was pointed out by David Friedman.  There were 3 categories that were used to decide if a paper agreed with the climate change consensus.

• Category 1- These papers explicitly stated that humans are the primary (greater than 50%) cause of recent global warming.  This accounted for 1.6% of the affirming papers.
• Category2- These papers explicitly stated that humans were a cause of warming, but weren’t specific on how much.  This means it wasn’t clear if they thought humans were a tiny cause, a moderate cause, or 100% of the cause.  This accounted for 23% of the affirming papers.
• Category 3- These papers implied (didn’t directly state) that humans caused warming, but again, weren’t specific on how much, or if there were other causes.  This accounted for 72% of the affirming papers.

Even on the study’s own terms, it’s pretty ambiguous what 97% of scientists agree on.  It’s unclear if scientists agree that humans have a significant, or small impact, let alone how much warming there might be in the future, and how dangerous (if at all) that warming would be.  However, by assuming a paper implied something, chances are the study wasn’t accurately capturing the viewpoint in some of these papers.  In fact, we know it didn’t, as several of the “97% of scientists” who were cited in Cook’s study as affirming his thesis, spoke out about what they thought of his study:

• “Cook survey included 10 of my 122 eligible papers.  5/10 were rated incorrectly.  4/5 were rated as endorse rather than neutral.” -Dr. Richard Tol
• “That is not an accurate representation of my paper...It would be incorrect to claim that our paper was an endorsement of CO2-induced global warming.”” –Dr. Craig Idso
• “Cook et al. (2013) is based on a strawman argument…By using the 50% borderline a lot of so-called “skeptical works” including some of mine are included in their 97%.” –Dr. Nicola Scafetta
• “Nope… it is not an accurate representation.” –Dr. J. Shaviv

Whatever one’s thoughts are on climate change, it should be clear this study should not be used as objective proof that the entire scientific community agrees that humans are the primary cause of climate change.  Doing this would be misleading.  Going further, as Obama, Kerry and the like have done, claiming that 97% think it’s “dangerous”, or that we need to have massive government involvement in the economy is completely wrong, as that was found nowhere in the study.  This is a non sequitur, as they take something found nowhere in science, or even the flawed study they’re referring to, but still attempt to cast a political belief as “science”.

Do Scientists Agree on Anything?

It’s pretty difficult to get 97% of anyone, let alone scientists, to agree on something, but there are some things that should be a consensus.

• Since the Industrial Age, the earth has warmed about .8 degrees Celsius.
• The greenhouse effect is a real scientific phenomenon.
• CO2 is a greenhouse gas, which we do emit from oxidizing fossil fuels, and it has gone from just under .03% of the atmosphere before the Industrial Revolution, to .04%.

Questions such as what percentage of the warming was caused by humans, how dangerous (or beneficial) is warming, how much will it warm in the future, and should we create a massive government bureaucracy to deal with the issue, have much less consensus.  In fact, some scientists argue that increased CO2 emissions might be a net positive, as it’s known to increase plant growth.

Established Science vs Predictions

Just as there’s a difference between the established science of meteorology, and the weatherman predicting if it will rain next week, there’s a difference between established climate science and what the climate will be in the future.  Any predictions of future temperatures are based on models, which have a pretty awful track record.  Climatologists might only be eclipsed by economists for their wrong predictions!  For an example, here’s a famous climate model from Dr. James Hansen, one of the most respected climate scientists, shown below.  Scenario A was supposed to be if we did nothing and let fossil fuel use go unchecked.  Scenario B was if we started slowing our fossil fuel use.  The actual climate turned out to be dramatically different from the model’s projections.

Far from being an anomaly, here’s another chart that groups together many different climate models.  Virtually every model seems to overstate climate change, usually pretty substantially.

Further Considerations

Even if we were to accept that all warming is man made and believe the climate models that can’t predict the climate, there are other things to think about.  If human progress and flourishing is your standard, fossil fuel use and CO2 emissions have actually been incredibly positive for humans.  Source: World Bank

Pick almost any category; life expectancy, clean water access, food, climate related deaths, personal income, etc.  Every one is highly correlated to energy use, particularly fossil fuels, in a positive way.  According to the UN, 1 billion people have been lifted out of poverty in the past few decades, despite (or because) the world has substantially increased fossil fuel use, and related CO2 emissions.  Climate related deaths are down an astounding 98% from the 1930s.  Even if you attribute all warming to human activity, it would be ridiculous to argue that the .8 degree climate increase in the past 150 years wasn’t worth it, on a human scale, relative to what we’ve gained.  We have a dramatically better standard of living, a safer environment, and even a cleaner one, if we look at it from a human perspective.  The developed world has gone from an environment where clean water was rarely available, where disease carrying insects wreaked havoc, where food was scarce, and climate events like droughts and storms resulted in massive deaths, to one where virtually the opposite is true.

If we have mild, or even moderate warming in the future, would that be just as an incredible trade off in the next 100 years in exchange for the fuels that power our lives?  If climate change is a catastrophic scenario, would looking to the government be the best solution?  What about all the drawbacks and costs of that relative to its benefits?  After all, their track record isn’t so great on fighting poverty, drugs or terror, and as Milton Friedman said, “if you put the federal government in charge of the Sahara Desert, in 5 years there’d be a shortage of sand”.  On these questions, the 97% claim becomes even less relevant, as the science surely isn’t settled, and there should be a debate.