Concrete and steel, or mangroves and forests? When it comes to climate adaptation, nature is much cheaper

What's the best way to protect ourselves against climate change? The default is to reach for concrete and steel to build seawalls, dikes, dams and drainage systems. These can work. But they are expensive and inflexible. There's another, much cheaper option which gets vastly less attention. Mangroves, forests and urban trees can help protect humans and their homes, farms and cities from floods, droughts, rising seas and heat.