What do woolly pigs have to do with climate change? They're part of a vital, ingenious and evolving strategy to take carbon out of the sky and store it safely -- in trees, soils, the ocean, buildings, rocks and deep underground. Every carbon removal approach takes some combination of natural resources, human ingenuity and technology, says climate thinker Gabrielle Walker. If we get the mix right, we can clean up the environmental mess we've made, reverse the processes behind climate change and give nature a chance to heal. "What goes up must now come down," she says.