Environmental Engineering Reference
In-Depth Information
Table 1.1
CO2 concentration levels and temperature increases
Stabilisation level
Likelihood of exceeding
(ppm CO2e)
2 °C
3 °C
4 °C
5 °C
6 °C
7 °C
450
78
18
3
1
0
0
500
96
44
11
3
1
0
550
99
69
24
7
2
1
650
100
94
58
24
9
4
750
100
99
82
47
22
9
Note
: Given the uncertainties, climate sensitivity is described in terms of probabilities against a range of stabilisation levels
and temperature increases at equilibrium relative to 1850 - representing average global temperatures across the surface of
the planet - ocean and land. Within this there will be much variation by area (Stern, 2009).
than at present. Huge climatic changes are likely, with very large adverse impacts on popula-
tions, particularly for those located at sea level or close to the major rivers or estuaries. This
includes the majority of the world's major cities.
Stern (2009) draws on 'contraction and convergence' principles (orginally developed by
Meyer, 2000) and develops a 'blueprint' for change, and he argues for an upper limit of 500
ppm CO2e. This implies a peak in global emissions within 10 years and an approximate limit
in volume at 20 GtCO2e (30-35 GtCO2e would be consistent with a 550 ppm CO2e target;
10-15 GtCO2e with a 450 ppm CO2e target). Given that global emissions are rising strongly
and are now at above 50 GtCO2e, reaching 20 GtCO2e implies a reduction in emissions by
more than 50 per cent relative to current levels, and around 50 per cent relative to 1990 and
2000 levels, which for global totals were similar. For developed countries this means: around
an 80 per cent reduction in CO2 emissions on 1990 levels - to around 2 tonnes per capita
per annum by 2050 (with the Climate Change Act 2008, this is now a legally binding target
for the UK). Economic growth also has an impact. If global output increases by 2 per cent
per annum until 2050 it would expand by a factor of 2.5. Halving emissions would mean
reducing emissions, per unit of output, by 80 per cent. The slow progress being made in
reducing emissions is problematic, meaning we will require much more dramatic action in
later years. Unless concerted global mitigation efforts are initiated soon, the goal of remaining
below 2°C will soon become unachievable (Peters et al., 2013), if it hasn't already.
As we can see, much of the debate around climate change has been confined to the natural
sciences and economics, and this has 'bounded' the analysis and also many of the proposed
solutions. The role of society has largely been absent in discussions, and this is a major
weakness: many social processes are predicated on high carbon lifestyles and travel behaviours,
and it is in understanding these that we might be able to find pathways to more carbon efficient
behaviours (Urry, 2011). This social science analysis, however, remains curiously remote from
the political decision-making process. Similarly, policy-makers have conventionally placed
their faith in technological options and their own ability to develop solutions to environmental
problems. Compared, for example, to alcohol or drug use, which are conceived mainly as
'social problems', the social dimensions of climate change are hugely underplayed (Murphy
and Cohen, 2001). Low carbon technologies are seen as a 'new market' for business and
consumption, even as a huge commercial opportunity. Whereas the social scientists would
see the economic growth paradigm as a significant contributor to the environmental problem,
and certainly not the mechanism for solving the problem (Jackson, 2009). So, we can see that
there are huge difficulties in the framing of the climate change problem, our understandings
