Before you short, read the Big Short and imagine yourself as Michael Burry. Very often you can be short, right, and lose your pants because markets are slow to recognize things that they are paid to ignore.
cjlars already brought up a similar strategy with less sensitivity to sea level changes and less sensitivity to interventions.
Maybe the best climate change hedge is investing in low carbon power production. (incrementally) Good for the climate, benefits if things go worse than expected.
No, that's exactly the problem. If you're betting on the market's irrationality fixing itself, you better be able to weather the storm of however long that takes.