Geoscience Reference
In-Depth Information
In terms of the study of palaeoclimate, during the 1980s there was also an intense drive to
understand how and why past climate changed. Major advances were made in obtaining
high-resolution past climate records from deep-sea sediments and ice cores. It was, thus,
realized that glacial periods, or ice ages, take tens of thousands of years to occur, primar-
ily because ice sheets are very slow to build up and are naturally unstable. In contrast, the
transition to a warmer period, or interglacial, such as the present, is geologically very
quick, in the order of a couple of thousand years. This is because once the ice sheets start
to melt, there are a number of positive feedbacks that accelerate the process, such as sea-
level rise, which can undercut and destroy large ice sheets. The realization occurred in the
palaeoclimate community that global warming is much easier and more rapid than cool-
ing. It also put to rest the myth of the next impending ice age. We now know that gla-
cial-interglacial periods of the last 2.5 million years were caused by the climate system
being influenced by the changes in the orbit of the Earth around the Sun. It is, thus, pos-
sible to predict when the next glacial period will begin, if there were no anthropogenic ef-
fects involved, which should be sometime in the next 1,000 years. According to the model
predictions by Professor David Archer (University of Chicago) and Professor Andrey
Ganopolski (Potsdam University) current levels of GHG emissions have already delayed
the next glacial period by 40,000 years, if we did everything possible to reduce future
emissions then the resultant carbon pulse would delay the next glacial by 120,000 years. If
emissions continue to rise at a 'business as usual' rate we could delay the next glacial by
over half a million years.
