That truth is that the United States and its closest allies use about twice as much fossil fuel as the rest of the countries, and being able to continue that is completely dependent upon a massive military campaign that stretches thinner as the years go by.
https://www.mtholyoke.edu/~paul20i/classweb/AFP2008/middleas...
Technologists can work on education and preventing the spread of war propaganda, which is rampant in Western television and media. Notice how the terrorists always seem to be loudly explaining which currently most strategic middle east country they come from.
If you want to believe the main problem is just that 'da earf is melting' or climate change or whatever, the root of the problem is still fossil fuel dependency.
The massive amount of fuel used for moving 3,000 pound vehicles to and from offices everyday, for work that probably 75% or more can be done over the internet with Skype or whatever, is the most obvious low-hanging fruit.
Another thing is, as the dollar hegemony fades, what replaces it, and what sort of conflict arises during that transition? Something like bitcoin might be a good alternative to WWIII.
We can also look toward alternative technological frameworks for society that support decentralization. Named-data networking, IPFS, Ethereum, etc.
Suburbia is a prime target for reform. Here is my idea: https://runvnc.github.io/tinyvillage/