Historically, glacial cycles of about 100,000 years are interupted by
brief warm interglacial periods-- like the one we enjoy today. Changes
in both temperatures and CO2 are considerable and generally
synchronized, according to data analysis from ice and air samples collected
over the last half century from permanent glaciers in Antarctica and other
places. Interglacial periods of 15,000- 20,000 years provide a brief respite
from the normal state of our natural world-- an Ice Age Climate. Our present
interglacial vacation from the last Ice Age began about 18,000 years ago.
Do rising atmospheric CO2 concentrations cause increasing global temperatures,
or could it be the other way around? This is one of the questions being
debated today. One thing is certain-- earth's climate has been warming
and cooling on it's own for at least the last 400,000 years, as the data
below show.
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