I think the biggest threat to humanity today is climate change. Not only does it make the Earth less hospitable to human habitation, but threatens civil society by putting people out of work, forcing migration, creating disasters.
I cannot solve it alone, but I can help in ways. One of the ways I choose to help is to plant trees across the World. Currently I’m helping to fund a reforestation effort in the mangrove forests of Madagascar through a site called Treecycler.
On Treecycler you can buy trees for $0.99 and chose one of a number of projects across the globe to receive the funds.