A Citizen’s Guide to Global Warming Evidence
Was it only me? I thought Chicken Little dead. After all, when was the last time we heard competent authority shouting “Only the government can stop the sky from falling!”? But there he was yesterday, singing his old song, and from the highest perch in the land.
Since the subject has come up, even though it pains to do so, we have to talk about it. Hence this modified and expanded repost. I’ll also have more in the near future.
Mind! Global warming can be dangerous. But, so far as we know, only politically and financially. Why, your own author lost jobs (and more) because of global warming. So unless you have balls of steel, as I do, beware what you say on this topic. This post originally ran 1 December 2009.
Why are you so scared about global warming? Why do you believe things are as bad as they are? Why is it you feel that the world is coming to an end unless we do something?
Unless you are an actual, God-love-you, bona fide climatologist, it is difficult to see how anybody could raise an interest in the state of the climate given the actual, direct evidence we have for dangerous man-made global warming. But it’s clear our National Nervousness Index is peaking. Why is that?
Chances are, that if you are worked up, it is because you are mistaken. If you are like most people—and most people are—then you have inappropriately thought that certain evidence implied the truth of dangerous man-made global warming (or AGW, for short) whereas it actually does not. You are therefore unnecessarily worried.
Here, then, is a brief FAQ which you can cut and paste on your energy-efficient refrigerator, or pass out to “activist” friends.
- The Earth’s climate has never been static It has always changed. And nobody—not a soul—knows what an ideal climate is. How can you say it will be bad if you don’t know what is good?
- AGW is not the only theory of climate change Something caused climate the change, but it may not have been AGW. There are many rival theories, but you have never heard of them. One, or even none, of them might instead be true and could be useful in predicting future climates.
- The accuracy of historical temperatures is questionable and is in flux We do not have direct measurements for most of the Earth’s history, and have to rely on statistics—-God help us!—to impute the missing records. The records used to compute past temperatures are ever changing, too; thus, so are the imputations. This process is fraught with error and uncertainty—uncertainty which is rarely or never carried through climate analyses, meaning we are too sure of the results.
- Historical temperature changes are not good evidence of AGW Because it was cooler, or hotter, in the past is not complete evidence that AGW is true. All historical temperature observations are consistent with all known rival climate change theories. Past temperatures are, at best, indirect evidence for many different climate change theories, and not just AGW.
- Statements of what happens when it is hot outside are not evidence that AGW is true If you heard that a glacier melted when it was exposed to hot air, you have learned what you already knew: ice melts when it is hot. Absolutely no observation of any plant, mineral, or animal is direct evidence of AGW. Thus, every horror story you have heard about small fish whose native waters got uncomfortably warm, about a species of grass that was stressed under the harsh sun, are not direct evidence that AGW is true. They are only statements of what happens when it gets hot out or when it rains or fails to.
- Every statement about what might happen if AGW were true is worthless as evidence for AGW Horror stories about the evil, wretched future that awaits us once the “tipping point” has been breached are not evidence for AGW. The statements are empty of any kind of proof. “Studies” that claim future awfulness due to AGW are inappropriately and disingenuously used to hint that AGW is true. This naughty behavior is equivalent to the Tokyo scientist who solicits his government for a Godzilla “studies” grant because of the havoc the nuclear-fire breather could cause if he were real. That his grant is awarded is not evidence of Godzilla’s existence. Nor are the string of papers published on crushed bodies, burnt cities, and the like evidence for Godzilla’s existence.
- The best indirect evidence for AGW is the fit of climate models to historical data AGW climate models can reproduce some of the historical data in some regions fairly well, but only in a statistical sense; they cannot fit data in all times or areas. However, many of those rival climate change theories fit the historical data equally well. Thus, the ability to reproduce historical data to an arbitrary level of goodness is not especially strong evidence in favor of AGW.
- There does not exist good direct evidence for the truth of AGW The only possible direct evidence would be if the AGW models skillfully predicted future climate data (skill means an improvement over a naive forecast such as persistence or rival theory). These skillful predictions would tell us that the theory underlying the models is likely to be true. AGW climate models do not skillfully predict new data. A forecast of doom is not proof of doom.
- The level of uncertainty in horrors caused by AGW is higher than thought A scientist writes a paper which states a horror is likely but not certain to occur if AGW is true and if a string of other conditions are met. This announcement is falsely taken as direct proof the horror will certainly occur. But the chance that the horror and AGW are both true and the string of conditions are true is necessarily less. Exaggerated example: it is 60% likely bee stings will increase if AGW true. But there is only (say) 10% chance AGW true. Therefore, there is only 60% x 10% = 6% chance we will see increased bee stings in the presence of AGW.
- The bandwagon effect is strong Isn’t it odd that researchers predict that warm, fuzzy, cuddly, photogenic species all face extinction risk if AGW is true, but they also say that species that bite, stick, pester, and plague will thrive if AGW is true?
I’m available to speak on this (and many other) topics. See the Contact Page.
This was originally a follow-up to my Pajamas Media piece on What is—and what isn’t—evidence for global warming.