Re:800,000 years of data insufficient (Score 2, Interesting)

Agreed. How do you calibrate instruments when there cannot possibly be reliable standards to compare against? Other proxy data? Scientists who argued against global warming relied upon satellite data. Scientists arguing the other side said that the dataset was tainted because adjustments were not made to accomodate orbital degradation (i.e., the influence of Earth's gravity on the satellite's path). If such a minute change can lead to drastically different results, the reliability of these ice core studies must be viewed with a high degree of skepticism.

Also, considering that the Earth is approximately 4.5 - 5 billion years old, ice core data covering only an 800,000 year period (about 0.02% of the Earth's lifespan) the dataset is too small to draw such large conclusions. Indeed, the fact that there is only 800,000 years of available data clearly indicates that the Earth was so warm that there were no icecaps before that time.

In a lecture (ahref=http://www.msu.edu/~larsong/isp203/Lecture_ 11.pdfrel=url2html-22472http://www.msu.edu/~larson g/isp203/Lecture_11.pdf>), Prof. Grahame J. Larson of Michigan State writes:

Analyses of oxygen isotope composition of foraminifera in numerous oceanic cores indicate twenty to thirty intervals of cooler, glacial climate during last 2 million years.

Record shows cooling trend began ~1.8 million years ago.
Since 800,000 years ago there have been 8 cooling events.
Periodicity of cooling events ~100,000 years since 800,000 years ago.
Prior to 800,000 years ago periodicity ~40,000 years.
Periodicity since 800,000 years ago follows ~100,000 year periodicity of Earth's ecentricity.
Cooling events initiated slowly, ended abruptly.
Last cooling event occurred ~110,000-18,000 years ago (Wisconsin glaciation) and cooling event prior to that occurred 190,000 to 130,000 years ago (Illinoian glaciation).
Warm interval (Sangamon) between last and prior cooling event lasted ~20,000 years.
Because of time for ocean to circulate isotopic signal lags 500-3,000 years behind corresponding glacier-volume variations.

Thus, we have small cycles of warming and cooling within much longer warm and cold periods.

Presently, the average global surface temperature is approximately 15 C. Over the life of the Earth, this temperature has fluctuated from 12 to 22 C. ahref=http://www.scotese.com/climate.htmrel=url2ht ml-22472http://www.scotese.com/climate.htm> We are thus coming out of a cold period. Whether that is good or bad is hard to say; but, I suspect it is likely to be more beneficial in the long run for mankind and other forms of life.