Greenland's recording of both natural cooling and warming climate change proves that modern global warming is modest at best - as the evidence indicates, in the scheme of past climate change, current warming is well within natural variation
The Little Ice Age (LIA) is a well documented climate change period that was a global phenomenon. For the Northern Hemisphere, the coldest temperatures were reached during the mid-to-late 1600's, and then a much needed warming rebound started.
For 337 years since the bottom of the LIA, the world has been slowly but surely warming. That rebound warming though has only amounted to an approximate 2.2C degree increase as indicated by the ice core temperatures (Kobashi et al. estimated a current ice core decadal temperature of -29.9C degrees).
So, in the scheme of climate change, how does this most recent warming compare to previous warmings (and coolings)?
Using the temperature reconstructions from the Greenland ice sheet, it can be determined what the temperature change and duration was for each of the last 10 cooling periods and the last 10 warming periods (including the period since the LIA). From this information we know the following:
- Climate change warming periods ranged in duration from 240 to 680 years
- Climate change warming periods ranged in temperature increases from +0.8 to +3.7 degrees
- Climate change cooling periods ranged in duration from 205 to 690 years
- Climate change cooling periods ranged in temperature increases from -1.1 to +3.1 degrees
In contrast to the previous 9 significant warming periods, the modern warming has lasted only 337 years (from trough to current peak) with a temperature rise of only 2.2C degrees. It has been the 5th highest warming of the 10 and is only average in duration.
In contrast to the previous 9 cooling periods, the Little Ice Age lasted 643 years (from peak to trough) with a temperature decrease of 1.6(C) degree. It was the 3rd coldest cooling of the 10 and is one of the longest in duration.
Conclusion: Over some 9,000 years, the ice sheets of Greenland have faithfully recorded natural climate change and the associated temperature changes. These past changes, both warming and cooling, have produced greater temperature changes and lasted longer than the current modern warming and the more recent Little Ice Age. Although increasing CO2 levels from human emissions may have enhanced our modern, modest global warming, the lion's share of the warming rebound is likely from natural forces, which produced the same in the long ago past, multiple times.
Note: We used a 200 year minimum span to identify significant duration periods of warming and cooling.