There seem to have been some big population upheavals in and into Europe at the end of the last Ice Age about 14,500 years ago, involving waves of immigration, coming over here etc. And it's good for us that it got warmer.
But the whole point of the current understanding of THIS climate change is that it's not natural - it's anthropogenic ie caused by our industrial and agricultural practices and our use of fossil fuels and so on, in a relatively short time,. The last big London flood is neither here not there, really - it's the increasing frequency of extreme weather events in recent decades that matters, and the scale of changes, over a relatively short time, involving rising average temps, fires, flooding, melting ice, rising sea levels etc.
