I expect that people will still write software because it needed and pays well. However, the jobs that people get paid to do could become rather different.

Consider what happens in a war. The people working on drones aren't just hobbyists, they're part of the war effort. Wars are not good for the environment, either.

So my guess is that, if it gets really bad, these jobs will focus more on short-term needs. Are people who are really focused on preparing for heat waves and drought and flooding going to give a hoot about being carbon neutral? An overloaded hospital is going to focus on the patients, not global environmental issues.