The year 2010 was one of weather extremes due mainly to the transition from El Nino to La Nina. The year has been much touted as the warmest in the last 150 years or at least the warmest since it was cooler. But, looking at a longer perspective, the 10,500 years of our current interglacial period, 2010 was cooler than about 9,000 of those years.
That is the contention of geologist Dr. Don J. Easterbrook. “One of the best ways to look at long-term temperatures is with isotope data from the GISP2 Greenland ice core, from which temperatures for thousands of years can be determined.” By looking at the ratio of oxygen- 16 to oxygen-18, the temperatures at the time snow fell over the glaciers can be determined. “The age of such temperatures can be accurately measured from annual layers of accumulation of rock debris marking each summer’s melting of ice and concentration of rock debris on the glacier.”
See Easterbrook’s full article here.