Transport planning: While this may not be save, it can mitigate impact while we find better solutions. Efficient vehicular routing logistics, like ride sharing, dial-a-ride, school bus problems.
Consume planning: We can also reduce how much we eat, say an app like "eat this much"stops people going overweight.
We can also plan how we distribute this food efficiently, think uber but for food.
Wageningen has shown amazing agro tech that makes them more productive. For example to save water, coordinating water sensors and weather prediction. Crop quality analysis by image processing, drones to pesticide.
But that is not code alone.
Indirect influence, this one is the most interesting, by helping people to lift their weights and do their jobs easier, learn better, etc. They might find how to save the world. Cool examples of this are in open source. Think on the relationships of Khan academy React and live editor.
Great list. Very practical and gives me a bit of hope!
4 is the sort of thing I’m really after!