Nasa has released a powerful animation mapping global warming trends between 1880 and 2015. It shows the changing temparatures over the last 100 or so years using a rolling five-year average. The blue colours represent temperatures cooler than average, while hues of orange signify temperatures warmer than average. It is taken from the 1951-80 baseline average. While the Earth appears predominantly blue in tone around the turn of the 20th century, there are noticable patches of orange that begin to appear from the mid-1930's. These gradually become more widespread, showing the long-term warming trend in action. Source: The Telegraph | 2 June 2017