One of the stated goals recent United Nations report on climate change is to prevent the planet from warming more than one and a half degrees Celsius. We ask what would happen if the world warmed by, say, two degrees.

Also: Calculating the cost of climate change is doable but difficult -- too difficult says the US Department of Defense; we fact check President Donald Trump on one of his recent statements about climate change; plus we take a journey to the remote Alaskan village of Shishmaref, where climate change and rising sea levels are a present threat.