Just as the perfect is the enemy of the good, proof can be the enemy of truth.
In my ongoing effort to understand the thinking of climate change deniers, I often jump on threads that arise on social media related to the issue. If you’ve never done it, try it. It’s educational. The deniers tend to chime in with various canned arguments,
assertions that temperatures are actually falling or that what we are experiencing is just a normal shift in the climate. They love to dredge up graphs of ancient climate fluctuations, CO2 levels ten times what we have today or stunning shifts in temperature as ice ages came and went. But at their core, all of the arguments are the same. “Where is the proof? You have no proof.”
And they’re right. We cannot prove in any simple or direct way that humans have caused climate change by the rapid burning of fossil fuels. The conventional scientific standard for definitive proof is a controlled experiment. Select a group of study subjects who are, to the extent possible, identical in every way and expose half of them to some variable of interest, leaving the other half as controls.
Experimental science is a powerful tool. We even have statistics to make sure that whatever differences we observe are not the result of chance variation. But this is where it gets sticky.
The ONLY way one can even begin to prove directly that humans burning fossil fuels is causing climate change is to find planets that are identical in every way, and insist that, on half of the planets, people stop burning fossil fuels. Then wait a few centuries and see what happens.
I can even tell you how many planets we need. Six.
Six planets would allow us to meet the conventional standard for proof by limiting the chance of incorrectly concluding that climate change was real (the so-called p value) to 5% or less.
I understand that six planets will be hard to come by. And even if we come up with them and we “prove” climate change is caused by CO2 from fossil fuels, there will still be a five percent chance we’re wrong, so the deniers would still have some wiggle room. But the six planet experiment is the only approach that comes close to the level of proof the deniers are insisting on. And, absent those six planets, they are willing to bet the one planet we’ve got that they are right.
Six planets. Hell, it would be nice just to have two, so we could have a spare after we’re done fucking this one up.