Serious question: what things/science/technology should you work on that can impact this and compound positively over time (outside of just changing your own personal habits, but not to say you shouldn’t do this as well)?
Help this project or those in a similar vein: https://www.theoceancleanup.com
As much as I am against Zoo's, they do a lot of conservation work, as do many museums. They have boards you can serve on to help guide investments. Saving the rain forest.
Engineer a disposable, insulating material that's actually biodegradable vs breaking down into microplastics to replace Styrofoam.
Similar to the above, for forks/knives/spoons/plates/bowls.
Support a healthy GMO movement that creates sustainable crops that use less acreage.
Shorten your commute, plant trees, don't mow your lawn, turn your computer off at night, potty train kids ASAP, drink water, cut back meat, carpool, don't burn anything.
Find ways to make the above easier for everyone and push for them. Acting locally will free up another motivated individual with better answers to act regionally, and that will trickle up. When the whole world is on fire, it's hard to focus on picking up that stray napkin. But if enough people pickup the coffee cups, we can focus on the next level up.
It could become an issue of technology if we discover some breakthrough, but wishing for that to happen isn't enough. We need to make use of the tools we have available today. And it needs to be done via legal means, because individuals alone cannot fix The Tragedy of the Commons.