It's the World Day to Combat Desertification and Drough, so it's a good time to check in on the Great Green Wall, a multi-country project in and around Africa’s Sahel region to re-green areas that have turned to desert because of overuse, expanding desert and climate change. Plus: a retired couple in China's Gobi Desert have been running their own regreening project for nearly 20 years, planting tens of thousands of drought-resistant trees by themselves!