Where did the 19th century data come from?
I'd like to know how they determined temperature changes in the 19th century in remote seas where no ships traveled.
But, yes, the world is warming. It's been warming since the little Ice Age which ended around 1800. The graphic only proves correlation with rising CO2, not causation.
The world has experienced peaks and troughs in temperature long before we started burning carbon. In the present epoch there seems to be about a thousand year cycle. It so happens that the temperature peaked around 1000 AD as well as 2000 AD. There were also cold spells around 700 AD and around 1500 AD. Until science can explain why these cycles happen, I won't believe carbon burning is the cause of the present warming.
