Geoscience Reference
In-Depth Information
Historical background
Scientists are predicting that continuing on our current carbon emissions pathway we could
warm the planet by between 2.8 and 5.6°C in the next 85 years, which economists suggest
could cost us as much as 20 per cent of world gross domestic product (GDP) to deal with.
In the face of such a threat, it is essential to understand the history of climate change and
the evidence that supports it. The essential science of climate change was carried out 50
years ago under the perceived necessity of geosciences during the Cold War, but it was not
taken seriously until the late 1980s. Since then climate change has emerged as one of the
biggest scientific and political problems facing humanity.
It is now over 100 years since 'global warming' was officially discovered. The pioneering
work in 1896 by the Swedish scientist Svante Arrhenius, and the subsequent independent
confirmation by Thomas Chamberlin, calculated that human activity could substantially
warm the Earth by adding carbon dioxide (CO
2
) to the atmosphere. This conclusion was
the by-product of other research, the central aim of which was to provide a theory suggest-
ing that decreased CO
2
was a major cause of the great ice ages. The theory still stands
today but had to wait until 1987 for the Antarctic Vostok ice-core results to confirm the
pivotal role of atmospheric CO
2
in controlling past global climate. However, no one else
took up the research topic, so both Arrhenius and Chamberlin turned to other challenges.
This was because scientists at that time felt there were so many other influences on global
climate, from sunspots to ocean circulation, that minor human influences were thought in-
significant in comparison to the mighty forces of astronomy and geology. This idea was re-
inforced by research during the 1940s, which developed the theory that changes in the orbit
of the Earth around the Sun controlled the waxing and waning of the great ice ages. A
second line of argument was that because there is 50 times more CO
2
in the oceans than in
the atmosphere, 'The sea acts as a vast equalizer': in other words, the ocean would mop up
our pollution.
This dismissive view took its first blow when in the 1940s there was a significant improve-
ment in infrared spectroscopy, the technique used to measure long-wave radiation. Up until
then, experiments had shown that CO
2
did block the transmission of infrared 'long-wave'
radiation of the sort given off by the Earth. However, the experiments showed there was
very little change in this interception if the amount of CO
2
was doubled or halved. This
meant that even small amounts of CO
2
could block radiation so thoroughly that adding
more gas made very little difference. Moreover, water vapour, which is much more abund-
