Environmental Engineering Reference
In-Depth Information
1.2.2 The Science
The science of climate change is very well established and its primary goal is to understand
the link between CO
2
and other greenhouse gas concentrations and temperature rise. Work
in this area has been carried out by the
Intergovernmental Panel on Climate Change (IPCC)
,
which was set up in 1988 by the World Meteorological Organisation and the United Nations
Environment Programme. It involves scientists from 169 countries.
Figure 1.2 shows the changing average global temperature, from 1850 to 2005. The bold
curve is the smoothed trend while the individual annual averages are shown as bars. The
temperatures are shown relative to the average over 1861-1900. The earth has warmed by
0.7 °C since around 1900, bringing the global temperature to the warmest level in over 12 000
years. All ten warmest years on record have occurred since 1990 and there is considerable
physical and biological evidence confi rming climate change. Most climate models indicate
that a doubling of greenhouse gases since the pre-industrial period is very likely to result in
a rise between 2-5 °C in global mean temperatures. This increased level is likely to be reached
between 2030 and 2060. If no action is taken concentrations would be more than treble pre-
industrial levels by 2100, resulting in a warming of 3-10 °C according to the latest climate
projections.
Although the relationship between CO
2
concentration, temperature change and undesirable
climatic changes is very complex and thus hard to predict precisely, it is widely believed that
the CO
2
concentrations have to be stabilized if damaging global warming is to be avoided.
The IPCC concluded in 2001 [4] that there is strong evidence that most of the warming
observed over the last 50 years is
anthropogenic
in that it is attributed to human activities.
This was supported by the Joint Statement of Science Academies (2005) and a report from
the US Climate Change Science Programme (2006). An IPCC updated report which was
published in 2007 confi rmed this link with greater certainty. A summary of recent scientifi c
research may be found in Reference [5].
Global Average Near-Surface Temperatures 1850-2005
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
Based on Brohan et al. (2008)
-0.4
1860
1880
1900
1920
1940
1960
1980
2000
Figure 1.2
Temperature rise record. ( © Crown copyright 2007, the Met Offi ce)
