When it comes to the bit in bold, I have done the best thing possible for the future of the planet (note: the planet; not the human race), and a small contribution to climate change, by NOT reproducing!
The vast majority of the problems on this planet, including climate change, could be prevented if there weren't so many of us consuming all the planet's resources. A LOT less of us, obviously. Nature has it's ways of controlling these things though, which is a bit of a worry for the younger inhabitants. I've had a good time during my time here, and feel fortunate to have lived through the golden age of just about everything, and avoided being involved in wars (so far) - but I have a real feeling that the good days for the human race are over.
Limiting family size is definitely a personal contribution that has value, just like not doing, or actively doing many other things.
Limiting family size usually comes alongside better education and empowerment of women too.
So good news both ways.
But it's not even the numbers of people, it's the amount each individual consumes and pollutes.
One westernised lifestyle contributes / uses a whole lot more carbon / fossil fuel footprint wise than a person in a country with more modest, or better adapted lifestyle expectations.
Although there is still an abundance of natural resources, available to all of us , in the form of contemporary sunlight, and its products..
We're just not so great at managing them for the long term right now.
Its up to governments ultimately to make the systemic changes that are necessary..
Its up to us as citizens to push our administrations to make these changes.
Tell them we think it's urgent, that we give a shoot.
Glad you've enjoyed your life so far though.
Misery is a costly thing, to body and soul.