The world’s grasslands are essential for holding soil in place, storing water and carbon, and providing food. And yet, up to one third of the Earth’s land surface is at risk of becoming desert, with potentially catastrophic consequences, not least for climate change. But figuring that out took a lot of catastrophic consequences for elephants.

In this recent TED talk, the ecologist Allan Savory explains Holistic Management, a land management technique that he says can rescue grasslands.

For a long time, experts blamed desertification on over-grazing. And in Africa, where Savory was working on national parks, he blamed elephants. So they started culling them, eventually killing 40,000 of the animals (this was back when you could kill elephants with impunity).

But killing the elephants didn’t work. Looking at parks around the world, Savory saw the same desertification happening everywhere. That’s when he realized that the key is to use animals to mimic the behavior of ancient herds that used to roam the land, and keep it in natural balance. Just like old herds of wild animals, cattle, sheep, and goats, move over the land, eating the grass, defecating, and pushing down the vegetation, so it decays, and can regrow. Leave it alone, and it starts to oxidate, and the only way to clear it is to burn it. That releases pollutants to the atmosphere, and offers only a partial fix.

Savory claims that Holistic Management is reversing desertification around the world, and could play a big part in reducing carbon in the atmosphere. He estimates that regenerating half the world’s grasslands could take us back to pre-industrial levels of CO2. His talk is worth a watch.