Geoscience Reference
In-Depth Information
Mitigation
The idea of cutting global carbon emissions by half in the next 30 years and by up to 80 per
cent by the end of the century may sound extremely challenging; however, already the UK,
Mexico, and California have made legally binding commitments to reduce carbon emis-
sions by 80 per cent, 50 per cent, and 60 per cent, respectively, by 2050. Professors Steve
Pacala and Robert Socolow, at Princeton University, published a very influential paper in
the journal
Science
which makes this challenge seem more achievable. They took the
business-as-usual emissions scenario and the desired 450 ppm scenario and described the
difference between the two as a number of 'wedges'. So on this view, instead of seeing one
huge insurmountable problem, really what we are faced with are between 16 and 20
medium-sized changes which add up to the desired big change (see
Figure 35
). They also
provided several examples for the wedges, each of them approximately saving 1 GtC every
year, as shown in
Table 5
. For example, one wedge would be doubling the efficiency of two
billion cars from 30 miles per gallon (~9.4 litres per 100 km) to 60 miles per gallon (~4.7
litres per 100 km), which is in fact a very achievable aim, as cars have already been built
that can easily do 100 miles per gallon (2.8 litres per 100 km). Though Steve Pacala and
Robert Socolow provide examples of what we can do to achieve the required cuts in GHGs,
each country will have different strengths and weaknesses, and can apply the most suitable
wedges for them. One of the first measures that all countries, industries, and individuals
can take is to be more energy efficient. At the moment, the energy use in an average home
in the USA is twice that of the average Californian home, while California's domestic en-
ergy use is twice that of Denmark. So already within the developed world there are huge
savings to be made just by improving energy efficiency. It remains a puzzle why industry
and business do not improve their energy use, as this can also significantly cut running
costs. Efficiency gains, however, will ultimately be taken over by increased use. For ex-
ample, if we did double the efficiency of two billion cars, this gain would be wiped out
once another two billion cars are put onto the roads. So one of the most important areas is
the production of clean, or carbon-free, energy, discussed later in this chapter.
