"Decadal average" refers to the average value or measurement taken over a period of ten years. It helps to understand the overall trend or pattern that occurs during that particular decade. Full definition
Despite large year - to - year variability of temperature, decadal averages reveal isotherms (lines of a given average temperature) moving poleward at a typical rate of the order of 100 km / decade in the past three decades [101], although the range shifts for specific species follow more complex patterns [102]. (journals.plos.org)
I've generated a graphic using the latest GISTEMP data that plots the anomaly over decadal average bars for decades 2005 - 2014, 1995 - 2004, and so on. (realclimate.org)
According to this diagram from the upcoming AR5 posted at WUWT by Bob Tisdale, it is going to be difficult to make the case for a pause when you have decadal averages plotted. (judithcurry.com)