It is easy to go see climate talks at Berkeley and as a social scientist I have to say that they usually make me uncomfortable.  If you go to an  astronomy or physics  talk,  nobody bats an eyelash when people  question the evidence for, say, Dark Energy.   (Criticizing the idea that speed of light sets an absolute limit on velocity definitely will encounter  resistance, but I’ve seen that done also.)  This pattern of evidence and push-back  has been going on since universities rejected scholasticism back in the 1100s.  It’s a pleasure to watch.

To an outsider, at least, the  climate  talks feel  different.  True,  speakers can  and often do criticize the evidence.  But they invariably begin and end with  the disclaimer that  “Of course global  warming is happening.”  Partly, I suppose,  this is about not wanting to be misunderstood in a  subject where obscure research sometimes ends up  in the newspapers.  But it’s pretty obvious that there there  are social  pressures at work inside the university too.  And that’s a pity.  Investigators shouldn’t  care what the answer is.  (None of us can really meet  this standard, of course,  but it’s inspiring to  see  people try.)

So  yes, I was disappointed by the e-mails.  And no, they aren’t damning to the point where we should  toss out the evidence and start over. Given that social pressures had so visibly crept into  the process,  they just aren’t that surprising. Still, it’s good for  the public to feel disappointment and even to  say  so.   That’s what keeps all of us honest.

Can we run the global warming debate better next time?  There are several problems that here.  The first  and  biggest is that society wants binary judgments — Does  global  warming exist  or  not.  Humans  are  notoriously uncomfortable with probabilities.  Science, on the other hand,  is about evidence.  And  the evidence is never 100%.

The other problem is  that global warming is a tough subject.  Physics works best for problems where the number of inputs is small  and small inputs have small  effects. Climate physics is remarkably difficult by that measure.  We probably understand  the interior  of the Sun  — or  even dark energy — better than we do climate.

Society’s insistence on certainty — maybe  zero,  maybe 100%, but nothing in  the middle — is a psychological fact.  But it is also the  wrong way to  do  policy.  If the chances of global warming were only, say, 78%, that  would  not  absolve us  of the  obligation to consider the probabilities  and act accordingly.  And indeed, there is an enormous  literature on  decision-making under uncertainty.

Global warming won’t ever be “proven” in this 100% sense.  All the  same,  it has  arrived and needs to be dealt with.  As the  old aphorism  would have it, “You can ‘t  win, you can’t break even  — and you can ‘t  get out of the  game.”