Proving Global Warming

At first opponents of global warming claimed that there was no warming.  Then they agreed that there was warming but it was not anthropogenic, caused by human activity.  Now they accept anthropogenic carbon dioxide is causing climate change, but they claim that it's not going to be as dire as climate scientists say it is going to be.

I've posted about "dire consequences" for at least three years so it's not a new topic for me.  It is possible that we may avoid the worst if we act now, but that isn't going to happen without people understanding what may happen if we don't.  Thus it is important to raise the issue of how bad it could be in order to motivate our response to global warming.

But that's not the point of this post.  I would like to bring everyone's attention to an article which supports proof for global warming forcing deniers to admit it is happening leaving them with having to claim that it won't be so bad.

This case is made by Seth Miller applying the work of Professor Bradford Hill who used it to supply a causal argument for cigarette smoking and cancer.  No one doubts that now, but in the 50's there were a lot of skeptics.  Cigarette smoking and cancer was a little bit like carbon dioxide and global warming today, but Professor Hill showed how we could have confidence in the causality.

Seth Miller is now applying his method to global warming.

Hill recognized that there are more ways to support causation that finding that two variables track. In fact, Hill identified nine separate strands of ‘proof’, each of which makes an independent case for or against causation. The list of nine aspects — and I’ll go into details below — are now called Hill’s Criteria.

Hill’s Criterion #1: Strength. How strong is the relationship between CO2 and temperature?

Read Miller's post for the definitive argument for there being proof.  Here are the criteria which Miller shows are satisfied in the case of global warming:

Criterion #2: Consistency. Is the data consistent across multiple measurements, at multiple places and times?

Criterion #3: Specificity. Is the change that we are seeing specific to this point in history?

Criterion #4: Temporality. Which came first in modern times, the CO2 or the warming?

Criterion #5: Dose-response. Does the temperature increase scale with CO2 increase?

Criterion #6: Plausibility. Does the causal relationship make physical sense?

Criterion #7: Coherence. Do the data fit in theory and knowledge?

Criterion #8: Experiment. Can we alter, prevent, or improve the situation with an intervention?

Criterion #9: Analogy. Is there an analogous, better-understood system that makes the CO2 climate hypothesis plausible?

Seth Miller concludes

Why I like Hill’s criteria. A magical thing about structure is that it gives you no place to hide.

When placed in Hill’s criteria, the strong points and weak points of the argument leap out. You know exactly what data you’d like to gather, if you had the chance. (Go find another planet to test our hypothesis on, for one). If there are holes in the plot of your story, the truth is laid bare for all to see.

If you believe alternatives to human-caused global warming, test them in this structure. See if the story holds.

The fact that we rely on stories to judge the legitimacy of an idea may strike some as lacking scientific rigor. So be it. I would love to put a probability behind the declaration that humans are causing climate change. But the world is too complex for us to reduce inquiry to a single number. Part of being a good scientist is to understand your limits.
All scientific work is incomplete, and at risk of being toppled by tomorrow’s discoveries. That does not give us leave from acting today.

The evidence supporting man-made global warming creates the one of strongest science stories I have ever seen.

And the nine criteria of Professor Hill is how we know.