The first UN climate change conference was held in 1995 in Berlin. More than two decades later, our planet remains on track for three degrees of warming above pre-industrial levels by the end of the century. The answer to avoiding this catastrophe is both simple and staggeringly complicated: drastically reducing and reversing the amount of carbon dioxide entering our atmosphere. How do we do this? Science correspondent Natalie Grover speaks to Prof Mike Berners-Lee, author of There is No Planet B, who has crunched the numbers on everything from carbon offsetting and green investments to e-bikes. Help support our independent journalism at theguardian.com/sciencepod