The U.S. has sponsored much climate research over recent decades, including the study of ice cores from Greenland. The National Climate Data Center (NCDC), a NOAA organization, maintains the Greenland ice core temperature data, which can be downloaded from their web site.
Fortunately, this Greenland ice core temperature data allows for an analysis of temperature change from minimum (trough) temperature to maximum temperature (peak) over extended time spans. Likewise, temperature change from maximum to minimum can also be analyzed. Sooo, what does that NCDC ice core temperature data actually indicate about temperature change?
1. Huge temperature swings have occurred naturally over thousands of years, prior to any human CO2 emissions.
2. The Modern warming increase (see pink arrow/dot on chart) since the bottom of the Little Ice Age (around 1840) has been minuscule versus all previous warming period temperature changes when compared to their respective cooling period trough that preceded.
3. Over the 9,000 years, the average temperature increase from the trough of the preceding cooling period to the next temperature peak has exceeded 2.0°C. In contrast, the Modern warming has barely reached a 0.7°C increase since the Little Ice Age cooling trough.
4. There have been nine significant warming trends leading to temperature peaks over last 9,000 years; and, all exceed the Modern warming trend in terms of absolute degree change (increase).
5. There have been nine significant cooling periods over the same time span. Many cooling periods have seen temperatures decline by over 2.0°C.
6. The average number of years between temperature warming peaks is approximately 990 years. Since the last peak around 1040 A.D., it has now been 970 years, which suggests the current warming period is close to peaking before the next natural cooling period dominates.
7. All scientists agree that all extreme temperature changes prior to the 20th century were of natural origin. In contrast, it's only climate alarmist scientists who believe that the temperature change since the Little Ice Age is all man-made (see pink arrow/dot).
(click on image to enlarge)
Note: The Greenland ice core data ends in early 20th century; the pink arrow and dot have been added to indicate the "consensus" temperature increase through 2009 since the LIA end mid-19th century.
Additional historical temperature charts. Climate history postings. Modern temperature charts.
