What does the analysis of the ice cores from the Greenland Ice Sheet Project tell us about Earth's past climate?

Below is a graph of the temperature of the atmosphere at the summit of the Greenland Ice Sheet over the last 40,000 years. The temperature of the atmosphere can not be measured directly from the ice cores but can be determined from a ratio of the oxygen isotopes present in the snow that fell each year. The last ice age ended about 11,500 years ago.

(Figure modified from Grootes et al, 1993)

6. What was the coldest temperature during this time period? How many degrees of change were there between the coldest temperature and the present day temperatures?

7. Did the temperature change slowly or quickly during this time period? How fast was the fastest temperature change and how many degrees of change were there?