After thinking about harm reduction, I thought we could apply the concept to global warming. Global warming is here and going to continue. Yet there are children and grandchildren being born; there will be people alive in "the future." It is easy to be despairing in light of the global challenges (we are, after all, in a climate emergency) and to worry that we cannot contribute. To keep up energy for the larger fight we must have small wins to celebrate. So apply the concept of "harm reduction." If you walk one day instead of taking the car you didn't contribute that journey's CO2 to the problem. If you can become a vegan you are no longer associated with the large emissions from the livestock industry, if you can buy carbon offsets for your flying you have contributed even more, contributed more "harm reduction," contributed less harm. And so on. 

See http://www.befairbevegan.com/the-planet.html