Twenty-eighth Report Adapting Institutions to Climate Change Cm ...

2.29 Some of the projected temperature changes shown in Table 2.1 and Figure 2-II may not at first
appear to be very large. But even a 2-3°C increase in average temperatures is far from trivial if it
is compared with a global mean temperature change of 4°C to 7°C between a full-blown ice age
and the peak warmth of an inter-glacial period. In the past these changes occurred very gradually
(over 5,000 years or so) and with much smaller human populations; the concern nowadays is
that recent observed and projected changes in global temperatures are more rapid, and hence are
unusual in the context of past changes. 30 In other words, projected increases of the order of 2-3°C
are sufficient to have profound impacts on society and the natural world.
2.30 But average increases in temperatures could be larger than this. In September 2009 the Met Office
Hadley Centre reported that there was a real potential for the global average temperature to warm
by as much as 4°C by the end of the 21st century, with a risk of some extreme regional variations. 31
The modelling work that led to this conclusion assumed a ‘business as usual’ emissions scenario
that did not include the impact of any mitigation policies (IPCC A1B scenario). It also concluded
that if the feedback processes between the carbon cycle and the climate are strong, this could
bring forward the time the Earth reaches a 4°C rise in average temperature by as much as 10 or
20 years. The Department for Environment, Food and Rural Affairs’ (Defra’s) Chief Scientific
Adviser, Professor Robert Watson, is quoted in mid-2008 as saying that the UK should strive
to mitigate for a global average temperature rise of 2°C but plan to adapt to a rise of 4°C. 32 An
increase of 4°C in global average temperatures would present huge challenges for society: “[I]n
effect there is no science on how we are going to adapt to 4°C warming.” 33
2.31
2.32
2.33
2.34
2.35
How should people use the UK Climate Projections (UKCP09)? Whilst they are the best tool
available at present for predicting future climate, as UKCP09 itself makes clear and as Table 2.1
and Figures 2-II and 2-III illustrate, there is considerable uncertainty about the exact nature
and degree of the change that the UK is likely to experience. Recognising and accepting this
uncertainty is itself an advance. Being ‘uncertain’ should not be a reason for not taking action on
adaptation by developing flexible responses.
Climate is not the only change we can expect. Other important areas of rapid change in society
include globalisation, technology, demography, the economy, regulation and cultural preferences,
all of which are uncertain. Uncertainty in the science of climate change is matched by uncertainty
in the way other drivers may impact on the UK and hence on the manner in which we adapt to
changes in our weather that will result from climate change.
As a first step in responding to the challenges posed by uncertainty, some organisations are already
considering how well they manage current extremes in the weather. A clearer understanding
of the manner in which we currently cope with extreme weather will indicate how a changing
climate may impact on day-to-day business.
Discussion of climate change often concentrates on detrimental effects. But, in the UK, climate
change may also offer opportunities – for example, there may be an expansion in the tourism
industry because the weather is warmer, and milder winters may provide medical benefits
including a reduction in excess winter mortality. The cover of this report reflects both the
possible benefits, as well as the hazards, to society from climate change. Both opportunities and
risks require adaptation.
Examples of both beneficial and detrimental effects are numerous. Within the water industry,
higher water temperatures may enhance biological processes for water and wastewater treatment.
But reduced summer rainfall will result in lower river flows, leading to less water dilution and
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Chapter 2