Climate Impacts of Anthropogenic CO2
As a species we are digging or pumping coal, gas and oil out of the ground
at a furious rate, and burning them in power stations, cement factories and
car engines. But what effect will these activities have on our climate over
the coming decades and centuries?
Tiny bubbles of ancient air trapped for millenia in Antarctic and Greenland
ice sheets, and then extracted in the now famous ice cores, reveal that the
natural level of CO2 in the atmosphere before industrialisation varied from
a low of about 200 ppm during ice ages to a high of about 280 ppm during the
much warmer interglacials, such as the one we occupy now. This gives a
natural range of variation of about 80 ppm. Climate was also about 5C colder
during ice ages, mainly because of the lower atmospheric CO2.
We were already at the high end of this range before the industrial
revolution kicked in. Since then we have raised atmospheric CO2 by a
staggering further 90 ppm. Now, in year 2000, atmospheric CO2 has reached
370 ppm and is still rising year on year. We have increased atmospheric CO2
by an amount similar to the glacial-interglacial CO2 difference, added on
top of the already high interglacial value. Given the severity of ice age
climates compared to now (e.g. hundreds of metres of ice covering Norway and
most of the UK, Canada and the northern US) we should not be suprised if we
see drastic climate effects in the future.
Ehux
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Toby Tyrrell : T.Tyrrell@noc.soton.ac.uk