The point is though that the sooner we do something, the less it will cost and the smaller the number of people that die or get displaced as a result.

In the documentary they argue that CO2 emissions and temperatures fluctuated wildly in the past and humans still survived. Ancient maps have been found that show Antarctica with no ice and trees etc. which would have meant much higher sea levels. But in the past, people would have been more nomadic and able to move and adapt easier because there were fewer people and no country borders to prevent them moving from one area to another if sea levels rose. Rising sea levels today would have a vastly greater impact - it would be far easier to move a few people, tents and goats but much harder to move the cities of London, New York or everyone in Bangladesh for example.