The reason Pascal's wager is bullshit is that it rests on two assumptions to convince non-believers:

1. Infinite badness of hell;

2. Infinitesimal possibility of religious truth.

Reasoning about climate change doesn't really involve multiplying infinity by zero. There is more evidence to back up a non-zero chance of catastrophe, and we don't have to rely on inifinite badness to make action worthwhile. Finite badness does the trick just fine.

Unlike Pascal's wager, the question of climate change action is rooted in knowable quantities. Unfortunately, a lot of these are still unknowns to a degree, and a lot of misinformation exists, making it difficult for non-experts to keep up.

Assuming that ice core data is being interpreted correctly, there is an almost guaranteed chance of catastrophic climate change sometime in the "near" future regardless of human impact: https://en.wikipedia.org/wiki/File:Vostok_Petit_data.svg

EDIT:

Looking at that a bit closer, I get peak temperatures at ~ 412.5k, 322.5k, 237.5k, 127.5k, and 7.5k years ago.

The other problem with Pascal's wager is widespread disagreement about what you really have to do to satisfy the alleged deity. Many religions claim that if you aren't a member of that particular religion, then you go to hell. Well, with all the different religions, that makes it pretty hard to choose the "correct" one, doesn't it? And if you're looking at the ways you have to limit your life and actions (e.g. not having premarital sex) to please this god, again, the different religions disagree hugely. Some religions say it's sinful to drink alcohol, others don't have this problem. Some say you can't eat pork or shellfish, again others disagree. Some religions say that you need to be completely celibate (I think the Shakers were like this), and not have any kids. So your odds of both choosing the "correct" religion and following its precepts acceptably are vanishingly small.

> "What if we do the good things that some religious book says we should do, avoid the bad, be decent human beings, and help others, and there's no afterlife to be rewarded by?"

> It is not a good sign if your worldview rests on reasoning like this...

Are you saying that it's not a good thing to have lived a good life and done good by your fellow humans?

Hmm, I'm having trouble figuring out your argument here. I see three premises:

Premise A: Pascal's wager is based on sound reasoning.

Premise B: People who live by pascals wager "live a good life", etc.

Premise C: "Living a good life" is a desirable thing.

Somehow you are arguing that if I reject premise A I must also reject premise C (if I were to act rationally), but I don't follow it.