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Scientific Consensus and the Obvious Truth about Global Climate Change

You-control-climate-changeI often ask questions in my article titles, but the question “are we responsible for climate change?” is simply unnecessary. From the overwhelming evidence, we know the answer to this question; and the answer is “YES!” This is good news because we may have the power to change things, but bad news because we aren’t doing nearly enough, and we may pass the point of no return within the next few decades. Furthermore, with so many people fighting to argue against what almost all climatologists are saying, most people aren’t even trying to do something about it.


A long time before I started writing articles on this blog, I was doing research for it. Without a doubt, climate change was the topic I had the most articles on, out of any topic – which says a lot, because I was only looking for psychology articles at that time. I have so many sources regarding the detrimental effects of climate change that I put off writing an article on this topic. I found articles faster than I could write about them. So I will keep things simple here and focus on the scientific consensus.

The scientific consensus doesn’t mean that something is true, but that experts think so. For example, we have a scientific consensus on gravity. Isaac Newton’s theory of gravity held for centuries, and that was the scientific consensus. But then Albert Einstein came along and shower it to be incomplete. Now that is the new scientific consensus.

There is even more scientific evidence to support evolution than gravity, and of course the scientific consensus is that it happens through natural selection. Note that the discrepancy between the education of evolution and the belief of evolution is almost exclusively caused by outdated and misguided religious beliefs, such as the absurd idea that the Earth is only five thousand years old or so.

Regardless, scientific consensus doesn’t mean that this is true – perhaps someone will create a new theory of gravity that will replace Einstein’s, just as he did with Newton’s. But climatologists spend their whole career on the study of climate, which would suggest that they know a lot more about what they’re talking about than the scientifically illiterate conspiracy theorist. And believe me, there are a lot of conspiracy theories about climate change.

Therefore, all though scientific consensus doesn’t necessarily mean something is true, it means that experts in that particular field think so. So if the scientific consensus says that water is good for you, decide for yourself how skeptical you want to be about it.

Especially in the last decade, climate change was one of the topics that the media wanted to invent a two-sided argument to. They would have debates with two “equal sides,” often showing an “expert” who so happens to have studied a field totally outside climatology. For example, some debates were between someone who studies climate against another who studies the weather. This is like getting a psychiatrist and a surgeon to argue about how to stitch up a patient – I don’t know about you, but I trust one more than the other.

So what do the experts say about climate change?

The Consensus on Climate Change

Skeptical Science is a website and research group that superbly aggregates research on climate change, as categorized by questions climate change denialists constantly ask. It’s basically a well-put-together FAQ that has probably better sourcing on climate change than any other website on the internet. They report extensively on the topic. The first major climate-change consensus study was from 2004:

In the scientific field of climate studies – which is informed by many different disciplines – the consensus is demonstrated by the number of scientists who have stopped arguing about what is causing climate change – and that’s nearly all of them.  A survey of 928 peer-reviewed abstracts on the subject ‘global climate change’ published between 1993 and 2003 shows that not a single paper rejected the consensus position that global warming is man caused (Oreskes 2004).

James Powell study graph

Last year, Massachusetts Institute of Technology (MIT) Geochemistry professor James Lawrence Powell ran an interesting study of his own, finding what you can see from the graphic on the right:

I searched the Web of Science for peer-reviewed scientific articles published between 1 January 1991 and 9 November 2012 that have the keyword phrases “global warming” or “global climate change.” The search produced 13,950 articles. See methodology.

There’s also a study from 2010 by William Anderegg and others which looked at scientists who either supported or rejected the consensus, omitting anyone who self-reported as unsure. From the abstract:

Here, we use an extensive dataset of 1,372 climate researchers and their publication and citation data to show that (i) 97–98% of the climate researchers most actively publishing in the field support the tenets of ACC outlined by the Intergovernmental Panel on Climate Change, and (ii) the relative climate expertise and scientific prominence of the researchers unconvinced of ACC are substantially below that of the convinced researchers.

The following graph of the Anderegg study comes from Skeptical Science:

Anderegg 2010 study results graph

All We Really Need to Know

We don’t even have to talk about the scores of scientific organizations, not to mention the Academies of Science from multitudes of countries stating their endorsements of the consensus – though these are also significant. The researchers at Skeptical Science just published their own large-scale investigation, whose results are not surprising when you consider the studies above.

A follow-up study by the Skeptical Science team of over 12,000 peer-reviewed abstracts on the subjects of ‘global warming’ and ‘global climate change’ published between 1991 and 2011 found that of the papers taking a position on the cause of global warming, over 97% agreed that humans are causing it (Cook 2013).

The scientific authors of the papers were also contacted and asked to rate their own papers, and again over 97% whose papers took a position on the cause said humans are causing global warming.

Just for the record, they contacted the researchers so as to ensure that a) they themselves weren’t biased in categorizing the studies, and b) the authors’ attitudes reflected their own studies. Indeed, the results show that over 97% of experts agree in both cases.

How important is 97%? This is an absolutely massive number. Almost every big scientific topic you can think of has less agreement. And considering how many experts there are on this topic, that is very significant. Many people still think that scientists are arguing about the results, but the consensus is clear. They almost all agree that climate change is anthropogenic (i.e., manmade).

Most of what we know about the ignorance of this fact comes from polls from America, but the same could probably be said for many other countries, though probably to a lesser extent. But for whatever reason, America seems to be unique in how many people are skeptical of the scientific consensus.

Perhaps that is because climate change has moved from an issue that both major political US parties aimed to fight, to one that Democrats like President Barack Obama fight for, whereas Republicans fight against. After all, a study published in April from Harvard University found that people with more Republican leanings, unlike their Democratic counterparts, were actually less likely to buy energy-efficient light bulbs when they were labeled with a message that said “Protect the Environment” than when there was no label. I suppose, then, it’s not skepticism – or even ignorance – that’s making some people deny anthropogenic climate change. Sadly, it may just be politics.

Could it be that the less than 3% of climate scientists who disagree with the consensus are leaning to the right? I don’t know. And it hardly matters – the number is so small that it’s dwarfed by the majority of scientists. That Harvard study, by Dena Gromet and colleagues, just shows that ignorance is bliss. At least, that’s true when it comes to getting Republicans to pay a little extra in order to help the environment. (Note: Protecting the environment never used to be a political litmus test in the US, but now it has bizarrely become perceived as something on the left-wing agenda.)

But the ignorance-is-bliss adage goes beyond that. One study from 2009 gives us what I think is the most important results of all the consensus studies. It essentially investigates how the degree to which people know what they are talking about influences their perceptions. Skeptical Science reports the following, along with the accompanying graph:

Subsequent research has confirmed this result. A survey of 3146 earth scientists asked the question “Do you think human activity is a significant contributing factor in changing mean global temperatures? (Doran 2009). More than 90% of participants had Ph.D.s, and 7% had master’s degrees. Overall, 82% of the scientists answered yes. However, what are most interesting are responses compared to the level of expertise in climatescience.

Of scientists who were non-climatologists and didn’t publish research, 77% answered yes. In contrast, 97.5% of climatologists who actively publish research on climate change responded yes. As the level of active research and specialization inclimate science increases, so does agreement that humans are significantly changing global temperatures.

2008 Gallup poll results Doran 2009 climate science consensus graphIn other words; the more someone researched climate change, the more likely they would be to agree that it is anthropogenic. This is very important for people to know.

But when it comes to staying informed, some of the blame must go to the media. Skeptical Science has a nice free app for those who want to learn more on the go. This is especially nice for Americans, who rarely get exposed to such science in the mainstream media. Even though 2012 was the hottest year ever recorded, there were still fewer stories in the US than every year since 2009. In fact, Sunday shows on the major US news networks (ABC, CBS, NBC, and FOX) spent less than 8 minutes on the topic of climate change for all of 2012.

Media Matters, the group responsible for this television analysis, reported that “the vast majority of coverage — 89 percent — was driven by politics, and none was driven by scientific findings.” Apparently NBC’s Meet the Press had the least coverage, with a single 6-second mention. It’s no wonder that so many Americans falsely think that scientists are in disagreement – they aren’t being told enough about it. Of course, media often bows to the pressures of ratings, which makes the situation much more complicated.

US scientific consensus on climate change perception graph

The Bottom Line

It’s very clear that scientists who study climatology are almost all in agreement that humans are responsible for climate change. What’s also clear is that the more people study the topic, the more they know about it; and the more they know about it, the more likely they are to come to the conclusion that is consistent with the consensus.

To put it another way… if 97 doctors out of 100 independently analyze you and tell you that you have cancer and you need to get treated, then it would probably be best to believe them. Or, you know, you could believe the 3%. But if you’re wrong… where does that leave you and your future generation?



Cook, J., Nuccitelli, D., Green, S., Richardson, M., Winkler, B., Painting, R., Way, R., Jacobs, P., & Skuce, A. (2013). Quantifying the consensus on anthropogenic global warming in the scientific literature Environmental Research Letters, 8 (2) DOI: 10.1088/1748-9326/8/2/024024

Gromet DM, Kunreuther H, & Larrick RP (2013). Political ideology affects energy-efficiency attitudes and choices. Proceedings of the National Academy of Sciences of the United States of America PMID: 23630266

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