Disparagement of Climate Change Research: A Double Wrong - Ethical Engineering for International Development and Environmental Sustainability - page 165

1.1 The Science

Light emitted by the sun, a body with a surface temperature of some 5,700 °C, con-
sists of electromagnetic radiation of different wavelengths, infrared and visible light
as well as some ultraviolet radiation. On average, each square metre of the earth's
surface receives about 288 watts of radiation (Houghton 2004 : 15). Were it not for
the presence of tiny amounts of certain naturally occurring substances, the amounts
of solar energy reaching the earth in the daytime and being emitted at night as infra-
red radiation would be in balance at a much lower temperature. In consequence, the
world would be an icy place at perhaps −6 °C, too cold to be liveable. Without 'this
aqueous vapour', 'the sun would rise upon an island held fast in the iron grip of
frost' (Tyndall 1863 : 417-418). It is a happy circumstance that the action of matter
such as volcanic gas and water vapour causes the lower atmosphere to absorb a por-
tion of the outgoing infrared radiation and raises the temperature to an average of
about 15 °C (Houghton 2004 : 15).
Once humankind started to make use of fossil fuels, the energy balance came to
be disturbed, fi rst only slightly, but the difference has become signifi cantly larger,
with the process going into overdrive since the mid-twentieth century. This is due to
the increased level of gases such as carbon dioxide and methane, emitted into the
atmosphere because of activities like agriculture, industry and transportation.
Because heat is trapped by these and other gases, they are often called greenhouse
gases, comparing the effect to that of the heat preserving panes of a greenhouse.
This means that there is an imbalance between the incoming radiation from the sun
and the outgoing infrared radiation into space. The difference leads to a gradual
warming of the earth's surface and the oceans in particular.
The fact that CO 2, the main gas generated by the burning of fossil fuels, absorbs
infrared radiation has long ago been demonstrated in the laboratory by John Tyndall
( 1861 : 25-28). We know from the study of carbon isotopes in CO 2 trapped in air
bubbles of ice core layers dating from different periods that the ratio of heavier to
lighter atmospheric carbon dioxide has decreased by 1.4 per mil since fossil fuels
began to be used (Quai et al. 1992 : 75). This is the case because the leaf pores of
plants take up more of the lighter than the heavier form during photosynthesis, as
the former moves more quickly. Accordingly, fossil fuels have a higher 12C/13C
ratio than the pre-industrial atmosphere.
In addition, fossil fuels do not contain 14 CO 2 ; as this, the only radioactive isotope
present in plant material - but only in extremely small quantities - has decayed dur-
ing the many millennia, it has been lying deep underground. Yet atmospheric 14 CO 2
content is important, even though less than 0.0001% of the total CO 2 , as it can be
used to establish the age of air samples (Shoemaker 2010 ).
The changed composition is once again a clear indication that climate change is
due to human activity. Other greenhouse gases, such as methane, nitrous oxide and
water vapour, block other wavelengths and so trap infrared radiation with a different
position in the spectrum (Houghton 2004 : Chapter 3). The fact that the average
surface temperature has remained at 0.8 °C above the 1960s average since about