I believe climate change is the biggest problem. I also believe that a lot of the problems with it are sociological, not technological or scientific. We have known about it and had solutions for over 30 years- it requires people, institutions and governments to actually take action towards these solutions. So science needs to educate- seeking knowledge for its own sake can be a selfish goal in these difficult times; we need to ensure that everyone understands the problem, how serious it is, and what we can and need to do next.
I agree with Ed, I think climate change is a massive global problem that we need to act on! We have to protect our planet for future generations and we need to do it now if we have a chance of reversing the damage that’s already been done!