5 year trends from surface temperature are not very significant and are a bad measure of anything. As everyone should know. But it seems that some people don’t. So in tedious detail…
Pick up the HadCRU temperature series from here. Compute 5, 10 and 15 year trends running along the data since 1970 and get (black lines data, thicker black same but smoothed, thin straight lines non-sig trends; thick straight blue lines sig trends):
From which you can see (I hope) that the series is definitely going up; that 15 year trends are pretty well all sig and all about the same; that about 1/2 the 10 year trends are sig; and that very few of the 5 year trends are sig.
From which the motto is: 5 year trends are not useful with this level of natural variability. They tell you nothing about the long-term change.