recorded history. The temperature at the North Poll is hovering in the mid 30s right now. Burning carbon based fuels has led to a gradual warming of the planet overall. This 2013 report is not-political and shows that there is plenty of evidence that will show possible effects by the end of the 21st century.
https://www.ipcc.ch/pdf/unfccc/cop19/3_gregory13sbsta.pdf