Conversely, bias corrections which vary over time can have a big effect on trends. (skepticalscience.com)
The inclusion of the very warm 1998 El Nino year at the end (or start) of either of those two periods only has a significant effect on the trend over the shorter period. (tamino.wordpress.com)
Over longer periods it can; t have a significant effect on the trend no matter how non-random it turned out to be. (tamino.wordpress.com)