1. Build a machine that pulls significant amounts of CO² out of the atmosphere.
2. Go to the UN an straight up tell them "we can make this problem go away, give us 1tn$ and 20 square kilometers of land in these countries, over this schedule with these milestones".
Or you could plant a tree.
The world is dumping 38 billion tonnes of CO2 into the atmosphere every year. (I'll ignore the additional gigatonnes we've already committed.)
That's $2.6 trillion per year for sequestration, just to stay even. (The value's actually lower than I'd expected.)
For comparison, global GDP is about $70 trillion, so this is 3% of global GDP.
Indeed, worth a book.