Quote:
Originally Posted by zimmy
The arguments that I just read said, well yeah it increased since the 1800's because of the mini ice age, well yeah there are more people now sow the temp probably increased. The next posts will be it hasn't increased and if it did it isn't because of people, it's sun spots. So what is it? Ask the real experts, they say the climate is (always)changing, the records show it is (always)changing, ice cores show it is (always)changing, we burn tons of fossil fuels as of the last 200 years. Where is the consensus from real climate scientists that it isn't happening(changing?)? You can't find one, so I should just take what Glen Beck or Hannity says to be the truth as the truth. Faggettit... I'll go with the science on this one.
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Let’s see just how the magnitude and rates of change of modern global warming/cooling compare to warming/cooling events over the past 25,000 years. We can compare the warming and cooling in the past century to approximate 100 year periods in the past 25,000 years. The scale of the curve doesn’t allow enough accuracy to pick out exactly 100 year episodes directly from the curve, but that can be done from the annual dust layers in ice core data. Thus, not all of the periods noted here are exactly 100 years. Some are slightly more, some are slightly less, but they are close enough to allow comparison of magnitude and rates with the past century.
Temperature changes recorded in the GISP2 ice core from the Greenland Ice Sheet (Figure 1) (Cuffy and Clow, 1997) show that the global warming experienced during the past century pales into insignificance when compared to the magnitude of profound climate reversals over the past 25,000 years. In addition, small temperature changes of up to a degree or so, similar to those observed in the 20th century record, occur persistently throughout the ancient climate record.
Figure 1. Greenland temperatures over the past 25,000 years recorded in the GISP 2 ice core. Strong, abrupt warming is shown by nearly vertical rise of temperatures, strong cooling by nearly vertical drop of temperatures (Modified from Cuffy and Clow, 1997).
Figure 2 shows comparisons of the largest magnitudes of warming/cooling events per century over the past 25,000 years. At least three warming events were 20 to 24 times the magnitude of warming over the past century and four were 6 to 9 times the magnitude of warming over the past century.
The magnitude of the only modern warming which might possibly have been caused by CO2. (1978-1998) is insignificant compared to the earlier periods of warming.
Figure 2. Magnitudes of the largest warming/cooling events over the past 25,000 years. Temperatures on the vertical axis are rise or fall of temperatures in about a century. Each column represents the rise or fall of temperature shown on Figure 1. Event number 1 is about 24,000years ago and event number 15 is about 11,000 years old. The sudden warming about 15,000 years ago caused massive melting of these ice sheets at an unprecedented rate. The abrupt cooling that occurred from 12,700 to 11,500 years ago is known as the Younger Dryas cold period, which was responsible for readvance of the ice sheets and alpine glaciers. The end of the Younger Dryas cold period warmed by 9°F ( 5°C) over 30-40 years and as much as 14°F (8°C) over 40 years.