Not even 25% of the GDP of the top ten nations. Seems like a much more worthy spend imo. Like all these billionaires want a dick measuring contest, let's see who can come up with the coolest carbon neutral tech, let's see which billionaire can fund the biggest national park or something.

My wife and I dream about building a zero carbon home. Solar roof, mass timber, carbon neutral cement, more environmental based temp systems like an actual thought about air flow. That or starting a commune in Scotland when the world collapses.