There is no need to be a mathematician in order to fight against climate change. Furthermore, it is very likely that there are better careers if you are aiming to do that. Nevertheless, it turns out that mathematics is one of the few things I know how to do. Being particularly concerned with climate change, I was wondering if my training as a mathematician (in fact, I have a PhD in pure/abstract mathematics) could allow me to tackle this problem. More precisely, I was wondering if it is possible to fight against climate change for a living as a mathematician.
Whether differential geometry can be used for research on climate change was asked here (not answered though). However, I am not restricting to differential geometry nor academia. Actually, differential geometry is not my field of expertise and I prefer not to work in academia since I would like to have more control on the city/country where I live.
I talked a bit about my background and personal preferences, but I believe someone under slightly different circumstances could also be interested in this topic. Hence, ideas not matching all my requirements will also be appreciated.
For example in the town where I am right now (Victoria, BC, Canada) there are https://www.pacificclimate.org/ and https://pics.uvic.ca/research, both with the explicit goal to not just stay within academia, but to collaborate with the private sector as well as local, provincial and federal policy-making. A quick glance through their projects and research should show that a mathematical background, even in pure mathematics, would be very helpful for this, and they would presumably be happy to have you. I know several people who work in that area who "came from" pure mathematics (in one case, even logic) but quickly learned the statistical and data-analysis tools to switch into this -- and certainly brought in fresh ideas from whatever background they had. I am quite sure that in many places, at least in North America and Europe, there are similar research groups, institutes and initiatives. To answer your question better, you would have to narrow down where you are and where you want to go.