 What is it? Where does it come from? And what can we do to curb black carbon emissions? For answers, we head to Nepal. The village that I visited was named Adeshwari, and it stood first atop of a hill very close to Kathmandu. And on a clear day, you could see the Himalayan ranges from there. Join me, Greya Jackson, on The Climate Question, right after the BBC World Service news.