Here's the best graphic I've seen for putting the numbers in context: https://xkcd.com/1732/
It's slightly out of date so we're actually at roughly +2 degrees C.
Basically, from year 0 CE to 1000 CE there was basically no change in average temperature. Then from 1000 CE to 1900 CE temperature actually went down about .5 degrees. Since then, we've gone up 2.5 degrees. So the past two thousand years temperature changed a total of .5 degrees down. We've increased about 5 times that in the past 100 years.