Yes, climate change is real. Yes, humans have played a role.

Today on the first full day of a new presidential administration that has already pivoted in digital media to downplay or possibly scrub climate change from the national conversation; and to join other scientists concerned with support of science including the science of climate change #USofScience, I am reposting my older post on science and climate change from a few years ago. The message is as relevant as ever. Climate change is real. The rapid climate change documented in recent history is tied to human activity. No amount of political argument or wishing it away can change that. I say that as a former climate change denier. I emphasize that climate data are what they are — carbon dioxide doesn’t care whether you are a Democrat, Republican, or Independent. Rapid climate change is occurring, and humans have played a role. What follows is my original and slightly tweaked post.


As the National Center For Science Education has been demonstrating for some time now, denying biological evolution and denying climate change are part of a larger phenomenon related to science illiteracy.   But I think we often tend to conflate the knowing of scientific data with knowing the process of science itself.  As a college professor, I can tell you that  smart students who know a lot about the natural world don’t always actually know the process of science.  In one of my first lectures to undergraduates in the introductory biology majors course, when I press them to define science, hypothesis, and so on, very few can.  And I have come to believe that our current societal issue with accepting science is a fundamental misunderstanding of the process, not simply a dearth of facts.

In my undergraduate days, I was a climate change denier.  That’s correct — I felt that the evidence was at best equivocal for global warming.  If you couldn’t prove it directly, how confident could we be?  In fact, I felt a good amount of the environmental “science” out there was nothing more than misplaced hysteria or political propaganda. For those who do know me and my political leanings, you are probably surprised.

So I speak from experience when I say that I understand the reservations among many people when it comes to climate change.  Ask any climate scientist, and they will never tell you with 100% certainty that their predictions will come to pass.  In fact, these scientists rely on models of climate, and those models are a hypothesis of reality, not reality itself.  Remember, I was a science major with aspirations of becoming a paleontologist, so my undergraduate self decided that if we couldn’t be certain, we shouldn’t go around broadcasting that it was the end of the world.  In my undergraduate head, the best science was certain, and that was why paleontology was so difficult — a lot of uncertainty.

So here’s the thing — a climate scientist can show you a lot of data (see below), and can tell you based on their expertise which are the most probable outcomes of current trends, but if you were my undergraduate self, you would not be convinced.

From Wikipedia Commons: “This image is a comparison of 10 different published reconstructions of mean temperature changes during the 2nd millennium.”

Whether or not my younger self (let alone my older self) was stubborn or simply a bit daft (probably both), I again point out a key feature in the thought process: if it isn’t certain, it’s not good science.

So, the assumption or implication that good science is certain is the first part of the puzzle.  The second part of the stubbornness by many of us to accept climate change or perhaps biological evolution is that we want evidence presented in a court room.  We want the TV show Law & Order, and we want the good lawyer to give us an iron-clad argument, or to show that our opponent is a lesser person, or to literally give us a smoking gun.  We are convinced that science works like this, and that the person with the best argument and evidence wins.  And most importantly, that the winner stays the winner.  Nothing can ever overturn the win.  Good science should be certain and win the day’s argument, for now and forever.

But of course, science has little or nothing to do with certainty and court room drama.  There is no certainty in science — there is simply probability.  Because a good scientist recognizes that we are only human, and we can only realistically deal in samples, we can’t measure every aspect of the known universe, and we certainly can’t have all the data on all the clouds, carbon dioxide, and local temperatures.  Therefore, a good scientist will never say they have “proved” something — rather, they will indicate that their data suggest certain scenarios are more probable than others.  The higher the probability, the more confident one can be that the predictions may come to pass.

It took a while for this concept to sink in with me.  It took graduate school and having to do science, and taking an excellent seminar from Professor Emeritus Ronald Toth at Northern Illinois University, that finally made science as a process click.

(As an important aside, much of my thinking as a scientist I owe to Ron — so the “smart” stuff I say about evolution and science are me emulating him.  My evolution podcasts and understanding evolution website are extensions [and I hope a sincere form of flattery] of Ron’s approach.  Thank you, Ron!)

That means, as someone who earned a B.S. in Geology with a Biology major, I had no real concrete idea about science as a process!  I am not surprised nor judgmental that many of our undergraduates, let alone the larger public, don’t understand this either — but this I believe is what needs to be most addressed.

Even if you do succeed in uncovering something new or accurately predicting a trend, there will always be new data. The complaint you often hear about science is how we keep changing our damn minds — we knew Pluto was a planet, or we knew that birds were not dinosaurs, or we knew that cholesterol was bad, and so on. But the process of science requires that one keep testing the hypothesis, and to incorporate new data as it comes in.  So we’re not changing our minds to tick you off — we adapting our models and our understanding of the natural world as more data come rolling in.

What I realized at long last in graduate school was that scientists speak in probabilities.  And when you think about it, we deal in probabilities all the time, and we make decisions based on those probabilities, and we are okay with that.  Every time you get in a car, there is a probability you will be in an accident … but you probably still get in that car.  Imagine if someone told you that unless you could 100% guarantee that no accidents would ever occur, it was pointless to drive.

Okay, but now for something more ominous: what about the probability that you will get sick if you ingest salmonella bacteria.  I have been sickened myself by this nasty “bug,” and many people have died from salmonella poisoning.  But there will always be cases where someone ingests salmonella or another pathogen and doesn’t become sick.  Now imagine a friend tells you that since every time a person has ingested salmonella they haven’t always become ill or died, we don’t have enough data to know whether or not it is truly deadly.  Therefore, wasting money and resources on preventing the spread of salmonella is not advisable because we can’t know with 100% certainty that everyone who ingests it will get sick or die.  This person would probably not remain your friend for long.

Probability in science works along this spectrum — from low to high odds.  Low odds: you will be hit in the head and killed by a rouge meteorite tomorrow.  High odds: the climate will continue to change, with an overall trend toward higher global temperatures.  Can we be certain climate will change in these ways?  Not 100%.  But the probabilities are high … and that’s why we should be concerned: the scientific predictions of increasing global temperatures suggest our world will change in ways that, if we are not prepared, will be devastating.  Of course, we could wait until we’re certain, and we could wait for the ultimate court room battle of the sciences … but if the probabilities are high, why wait?  What are waiting for?  Waiting for all the data to come in (which will never happen) and waiting for 100% certainty (which will never happen) is simply another way of doing nothing in the face of probable danger.

If you understand that the process of science is by its very nature is one based on probability, not certainty, I think we begin to get to the heart of the scientific illiteracy problem.  Giving people more and more data won’t help if they sincerely believe that uncertainty means no one knows anything.  This is, I believe, the core issue with science literacy — and why our politicians, our media, and our public are so often mislead to disregard good science and its important predictions that effect us all.

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