By David Appell

On the Portland School Board's decision to ax certain textbooks for their position on climate change, The Oregonian/OregonLive editorial board recently wrote, "The board's climate-change resolution is not intended to teach students to think critically, which is what schools should do. It's designed, instead, to produce acolytes."

The first responsibility of any school is to teach what is known. Man's influence on climate is by now well-established, as the board notes. Climate contrarians, despite all their bluster, have never put forth an alternate scientific explanation for modern warming that explains what we see.

If I were a Portland public school teacher, I would happily give my pupils a good, long hard look at the contrarian's positions on global warming -- and show them exactly why they are full of holes, of tricks and poor science that don't agree with observations, and why man's emission of greenhouse gases are a far superior hypothesis to explain what's going on.

Because, after all, the vast majority of scientists now accept man-made climate change, and they do so because it agrees with and explains observations.

Recent months have seen record temperatures. Yes, we are coming off a strong El Nino. But this El Nino has seen surface temperatures 0.7 to 1.4 degrees Fahrenheit above even the last strong El Nino of 1997-98.

It is not difficult to give students a basic understanding of why man is adding to the planet's greenhouse effect. The Earth emits infrared radiation -- heat radiation that our eyes cannot see -- and atmospheric greenhouse gases like carbon dioxide absorb it. The more carbon dioxide up there, the more heat absorption that takes place. These molecules then re-emit heat radiation in a random direction, and some of it goes downward.

That's your global warming. Well known since at least 1896.

But it is the rare high school student who will know enough science -- enough thermodynamics, enough math, including advanced calculus, and enough quantum physics -- to definitively decide for herself that man is the cause of modern warming. There are, I think, simply too many subtle and deep scientific points in the argument.

This should not scare teachers off. Very few of us can think our way through the evidence showing that smoking causes lung cancer and heart disease. No calculation proves it. Or the math showing that coalescing black holes emit gravitational waves, as was recently discovered at the LIGO (Laser Interferometer Gravitational-Wave Observatory) lab near Tri-Cities, Washington. But all these are true.

This is why there is so much emphasis on a scientific "consensus" about man-made climate change -- because very few of us can rigorously decide for ourselves. Climate contrarians take advantage of this to confuse us with pseudoscience that sounds plausible, but is anything but on close examination. It is all outside the expert consensus.

"Consensus" does not appear in any other sciences. The existence of quarks or the properties of black holes aren't time-crucial to the public. But climate change is very important to us all, so if the average reader can't grasp all the science, the least that can happen is to be able to hear about the prevalence of expert opinion.

Sure, there are always a few Ph.D.s who are outliers. That doesn't make them right. Science fights this out. The contrarians finally lost about 20 years ago, but invested interests still keep a few of them afloat.

If 400-plus years of science has shown us anything, it is that science is the most successful method of obtaining knowledge that has ever been devised. If wrong, it corrects itself. When right, researchers move forward to the next challenges. In this case, how man-made climate change will manifest, and how it will impact humans and other species.

This is the most difficult calculation that mankind has ever attempted.

I don't know if science teachers have enough preparation time to make this kind of argument. But I hope they don't feel it necessary to "present both sides." Because the science falls strongly to one side -- the man-made one.

Temperatures keep going up and up. Ice keeps melting. The ocean's level keeps rising. All this is happening for a reason. That reason is us.

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David Appell, Ph.D., is a freelance science journalist living in Salem.