Gardiner V., Matthews H. The changing geography of the United Kingdom

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averaging 8 per cent more. Even before we start to factor in climate change,

therefore, it is important that this level of thirty-year natural climate variability

can be accommodated within our economy and institutions. Furthermore, the level

of natural variability to be expected on shorter time-scales, for example decades,

is even larger.

FIGURE 19.13 Natural variability of thirty-year means of annual and seasonal precipitation and

temperature for different regions of the UK. Data are extracted from the 1,400-year control simulation

of the HadCM2 climate model. Box plots show absolute range (dots), the ±10 per cent extremes

(boxes), and the inter-quartile range (extended horizontal bars). Anomalies are with respect to the

1,400-year mean

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Future climate with climate change

We know, however, that other external factors will cause global climate to change,

quite apart from natural variability. The largest of these forcing factors over the

next century is almost certainly going to be increasing atmospheric concentrations

of greenhouse gases. Since we do not know at exactly what rate these gases will

accumulate in the atmosphere and since we do not know exactly how sensitive the

climate system is to such accumulation, it is usual (e.g. Hulme and Jenkins 1998) to

calculate a range of climate change scenarios rather than present a single estimate.

When we do this for the UK then by the 2050s mean annual temperature as a result

of anthropogenic climate change may be between about 0.9°C and 2.3°C higher

than the 1961–90 average, a warming rate of between 0.1°C/decade and 0.3°C/

decade. This rate of UK climate warming should be compared with the annual

warming rate as measured by the CET over the last two decades, which is about

0.15°C/decade. In other words, UK climate has been warming over the last thirty

years at an average rate that we anticipate will be representative of the next one

hundred years. We are already living under conditions of twenty-first century climate

change.

We can show what this range of warming rates means for the climate of the UK in

a different way. Table 19.3 shows the proportion of the UK land surface that falls into

different mean annual temperature zones, first for 1961–90 (current climate) and then for

the period centred on the 2050s (future climate), but under the four different climate

change scenarios presented in the UKCIP98 scenarios (Hulme and Jenkins 1998). The

small proportion of land with mean annual temperature below 6°C contracts from 5 per

cent to between 1 and 4 per cent, while at the other extreme the proportion of land with

TABLE 19.3 Percentage of the UK land surface falling in different mean annual temperature zones for

1961–90 climate and for the thirty-year period centred on the 2050s, assuming the four UKCIP98

climate change scenarios. The scenarios are termed ‘low’, ‘medium-low’, ‘medium-high’ and ‘high’.

The global warming shown is with respect to the 1961–90 average

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mean annual temperature above 12°C increases from zero under present climate to between

1 and 8 per cent by the 2050s. It is important to note the considerable range in these

figures, a range that results from assuming different future emissions scenarios and different

global climate sensitivities.

The changes in mean seasonal precipitation that accompany this climate warming

are even more variable. Under all four scenarios annual precipitation increases by

between 1 and 6 per cent, but there are marked seasonal and geographic differences.

Thus winter precipitation increases by between 5 per cent (‘low’ scenario) to 15 per

cent (‘high’ scenario), with slightly larger percentage increases in the South than in the

North. Summer precipitation decreases in southern UK by between 2 and 18 per cent,

but increases slightly over northern UK by up to 5 per cent. These changes in summer

precipitation are not large in the context of the natural climate variations discussed

above.

Given the above changes in mean temperature and precipitation in the UK, what

associated changes in other climatic and non-climatic variables may occur, and what

significance may they have for different sectors of the UK economy and environment? We

continue by describing changes in atmospheric carbon dioxide concentrations, sea-levels

around the UK coast and the frequency of storm events.

Changes in other climatic and environmental variables

Different emissions profiles of greenhouse gases over the next century will lead to

different atmospheric concentrations of carbon dioxide. The emissions profiles

assumed in the UKCIP98 climate change scenarios lead to estimates of carbon dioxide

concentration of between 443 ppmv and 554 ppmv by the 2050s, an increase of

between 33 per cent and 66 per cent over average 1961–90 concentration (Hulme and

Jenkins 1998). The latter is close to a doubling of the pre-industrial carbon dioxide

concentration of about 280 ppmv. These estimates do not allow for any deliberate

policy-related reductions in carbon emissions, such as have been written into the

Kyoto Protocol. However, even were this Protocol to be fully ratified and adhered to,

reductions in atmospheric carbon dioxide concentrations by 2050 would be modest

(Wigley 1998). This increase in concentration of a major atmospheric plant nutrient

will lead to a general increase in photosynthetic rates for most UK plants and, due to

closure of stomatal pores, a general increase in water-use efficiency. Combined with

increased temperatures and nitrogen deposition from the atmosphere, these changes

will generally be beneficial for plant growth (CCIRG 1996). The exceptions to this

will be where plant growth is moisture-limited and where excessively high

temperatures inhibit plant photosynthesis.

In the previous section we showed examples of rising sea-level around the UK coast

as measured by tide-gauge data. Climate warming will contribute to accelerated rises in

mean sea-level due primarily to thermal expansion of ocean water and to land glacier melt.

Under the climate scenarios described here, mean sea-level is estimated to rise over average

1961–90 levels by between 13 cm and 74 cm by the 2050s (Table 19.4). As mentioned

earlier, however, this mean rise due to climate change will be moderated by the background

change in crustal movement. Thus coastline emergence in Scotland will reduce the net

change by up to about 11 cm, while coastline submergence in southern UK will increase the

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net change by up to about 9 cm (Table 19.4). The significance of such a change in mean

sea-level will depend greatly on the accompanying changes in storminess and the local

shoreline morphology. Figure 19.14 shows one example, for Harwich, of how the return

period of a given tidal limit would shorten with a 41-cm rise in mean sea-level and assuming

no change in storminess. A tide-level of 5.6 metres above datum with a return period

currently of a hundred years, becomes a 1-in-10 year tide-level by the 2050s (see also

Chapter 17).

Having mentioned possible changes in storminess, what would this scenario imply

for storm frequencies across the UK? Although modest increases in mean annual wind

speed occur (Hulme and Jenkins 1998), the changes in gale frequencies are very much

less clear. Table 19.5 shows the changes in the frequencies of three different categories

of gales—gales, severe gales and very severe gales—for three different periods over

the next century. For the winter season, there is a suggestion that overall gale frequencies

may decline in the future, although very severe winter gales may increase. Note that the

changing sign of the changes in severe gale frequencies between the three different

periods indicates that a clear anthropogenic signal in severe gale frequencies is not

easily detected from the noise of natural variability. For the summer season gale

frequencies are much lower (less than 2 per year) and consequently any changes in gale

frequencies are less significant. Nevertheless, by the 2080s this scenario suggests a

modest (approximately 10 per cent) increase in the frequency of all categories of summer

gales.

Environmental impacts of climate change

The climate change scenarios described above would have a variety of impacts on

different environmental assets and economic activities in the UK. We summarise a few

of these based on the UK government’s Climate Change Impact Review Group report

published in 1996 (CCIRG 1996) and summarised by UKCIP (1998). These impacts

are far from definitive and in most cases the studies upon which they are based have not

considered the interactions that would occur across or within sectors; nor have they

fully evaluated the adaptive responses that may be triggered. Nevertheless, they give us

TABLE 19.4 Representative changes in sea-level (cm) around the UK coast by the 2050s due (a) to

global climate change only (‘Climate’) and (b) to the combined effect of climate and natural land

movements (‘Net’). Changes are with respect to 1961–90 mean levels

Source: Hulme and Jenkins (1998).

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a first-order impression of what climate change may mean for selected aspects of the

UK environment.

The climate warming would be likely to result in shifts in natural habitats for

wildlife species (including diseases and pests) northwards by between 40 and 70 km/

decade. The actual ability of a species to migrate will vary greatly, however, between,

FIGURE 19.14 Estimated change in tide-level return period for Harwich in East Anglia assuming a

41-cm rise in mean sea-level by the 2050s. The example highlighted shows that the 100-year return

tide-level of +5.6 metres becomes the ten-year tide-level by the 2050s. No allowance is made for

changes in storminess

Source: Hulme and Jenkins (1998).

TABLE 19.5 Percentage changes from the 1961–90 reference period in seasonal gale frequencies over

the British Isles for 2020s, 2050s and 2080s for the UKCIP98 Medium-high scenario. The 1961–90

frequencies are calculated from climate model outputs and not from observations

Source: Hulme and Jenkins (1998).

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say, an insect and a tree. With an increase in mean precipitation over northern UK

also being accompanied by an increase in the intensity of precipitation, river flooding

frequencies in north-west England, Scotland and Northern Ireland are likely to

increase. In south-east England, however, reductions in summer precipitation would

increase drought frequencies and/or drought intensities. More intense thunderstorms

would cause flooding, but would fail to benefit either water supplies or soil moisture.

Coupled with increased evaporation such a scenario would create a landscape of drying

rivers, desiccated soils and forest fires in summer, creating problems for, among others,

farmers, forest owners, pleasure boat operators, water companies, anglers and fire

fighters (UKCIP 1998).

Natural habitats at risk from climate change include the heaths of southern England

(which are vulnerable to fires), wetlands (such as the Scottish peat bogs and Sussex water

meadows) and rare mountain habitats. CCIRG (1996:xii) warned that, ‘a substantial number

of the 506 species listed in the Red Data Book as being endangered, vulnerable or rare,

could be lost as a result of climate change’. Substantial areas of mudflats and salt marshes

would be at risk from inundation from rising sea-levels. Salt intrusion could be an even

bigger problem than rising water levels themselves. A substantial proportion of the UK’s

Grade 1 agricultural land could become saline since nearly half of such land is below the 5-

metre contour.

Another area that CCIRG (1996) reported on was health. Climate warming in the UK

as described here would likely lead to a reduction in winter death rates, but an increase in

heat-related mortality, ranging from asthma (exacerbated by rising urban air pollution levels)

to heat-stroke and drowning. The risk of food poisoning from E-coli, salmonella and toxic

chemicals in shellfish could increase. Hay fever would occur earlier in the year and could

be more intense (UKCIP 1998).

Climate policy in the UK

There are two fundamental responses to the realisation that human-induced climate change

may have potentially adverse consequences for the environment and society. These are

mitigation and adaptation. Mitigation seeks to reduce the magnitude of the climate change

by reducing emissions of climate-warming greenhouse gases or by strengthening the

biospheric sinks of these gases. Adaptation seeks to intervene in environmental or economic

systems at a management level to reduce the vulnerability of such systems to climate

change. Both responses are important and both are being pursued as part of UK government

policy.

Climate mitigation policy

UK national emissions of carbon dioxide in 1990 were about 158 million tonnes of carbon

per year, less than 3 per cent of the global total. With about 1 per cent of the world’s

population, however, per capita carbon emissions in the UK were about three times the

global average. About 95 per cent of these emissions come from the burning of fossil fuels

for energy use. As part of the Kyoto Protocol, the UK has agreed to reduce emissions by 8

per cent from 1990 levels by the year 2012, a target which requires annual carbon emissions

to fall to 145.4 million tonnes of carbon. During the 1990s, carbon emissions have already

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fallen by some 10 million tonnes, largely as a result of fuel switching from coal to gas and also

as a result of lower energy consumption per unit of GDP. On the other hand, emissions from

the transport sector have been steadily rising and it will be necessary to monitor future emissions

levels carefully in the years to come to ensure that the Kyoto target is met by the UK.

Despite these successes in reducing UK greenhouse gas emissions, the overall success

of a climate mitigation policy depends entirely on the collective actions of the world’s

major emitting nations. No climate benefits are gained by reducing emissions in one country

if these are more than compensated for by increased emissions elsewhere. It is for this

reason that the Kyoto Protocol agreed collective action by the world’s industrialised nations

(so-called Annex-1 countries) to achieve a net 5.2 per cent reduction in greenhouse gas

emissions by the year 2012. The climate gains from such a global mitigation policy are

likely to remain small, however, if expressed purely in climate terms. Figure 19.15 shows

the effect on global temperature and sea-level of a literal and complete adherence to the

Kyoto Protocol. Temperature change by 2100 is only about 5 per cent lower than it would

otherwise be and the reduction in the rate of sea-level rise is even smaller. Such outcomes

would do little to alter the climate changes and resulting impacts described in the previous

section.

Substantial mitigation of human-induced climate change will therefore depend

on two further criteria. First, the agreement by Annex-1 nations for more far-reaching

emissions reductions beyond 2012 and, second, the inclusion of non-Annex-1

nations—the world’s developing countries—within the Protocol. This latter condition

is only likely to be met subsequent to Annex-1 nations achieving the initial Kyoto

FIGURE 19.15 Simulated changes in global-mean temperature (left) and sea-level (right) from 1990

to 2100 assuming a reference emissions scenario (top curve) and a literal and full adherence to the

Kyoto Protocol (bottom curve). As a consequence of the Protocol, temperature change by 2100 is

reduced by about 0.15°C and sea-level rise by about 3 cm

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target and demonstrating a commitment to reducing their very high per capita carbon

emissions to a level closer to the global average. Neither of these two criteria will be

achieved easily.

Climate adaptation policy

For these reasons, a second and perhaps more important strand to an integrated national

climate response policy is the need for adaptation. Despite the best efforts at either UK

national or global scales to reduce greenhouse gas emissions, our historical emissions of

these gases combined with the inertia of the climate system means that we are ‘committed’

to a substantial amount of climate change. This ‘committed’ climate change may not be

greatly different from the changes described in the previous section. It is essential therefore

that we also develop practical policies to adapt to the consequences of the climate change

that will occur.

Adaptation to climate change is a more achievable policy response than climate

mitigation. This is because it can be implemented by individual countries, or even within

individual sectors within countries, and does not depend on international agreement.

Furthermore, many adaptation options can be implemented using existing decision

frameworks. Many decisions about investment levels, infrastructure design criteria and

resource management are risk-assessment decisions. What level of risk are we prepared to

live with and what level of investment do we need in order to achieve that level of risk?

There are many examples of where climate variability already affects such decisions and

where adaptation to climate change therefore simply requires an appropriate adjustment of

the probabilities of certain weather or climate extremes occurring. Water resource

management and coastal protection are two examples of where such adaptation is already

occurring. The UK water industry has been issued with climate change adjustment factors

to use in calculating future run-off in different UK catchments (Arnell et al. 1997). These

factors allow for scenarios of temperature, evaporation and precipitation change caused by

global warming and should ensure a wider safety margin in the future provision of adequate

and timely water for domestic and industrial consumption. In the other example, the planning

of new coastal protection infrastructure has been required to incorporate changes in the

design criteria for certain projects, in this case an additional rise in mean sea-level at the rate

of 3 mm/year.

Conclusion

The co-evolution of climate and society raises a number of paradoxes concerning their

relationship. On the one hand, the development of a technologically advanced society has

overridden some of the traditional controls exerted by climate on human activities. Thus in

the UK we are no longer subject to climate-induced food shortages, or even fluctuations in

food supply, and the growing contribution of the financial sector to the UK national economy

is less affected by weather variations and climate changes than were the traditional

manufacturing industries of the early century. At a trivial level, because of undersoil heating

we can continue to play football on outdoor pitches in the middle of a freezing winter. Yet at

the same time we have a growing sense of our vulnerability to climate extremes, whether

this vulnerability is related to water shortages and hosepipe bans or the effects of severe

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windstorms or coastal flooding. This paradox is further compounded when we consider

that it is the very advancement of our carbon-intensive technological society (supposedly

making us more immune to the influences of weather) that in turn is causing changes to our

climate regime (supposedly fuelling angst about our ability to cope with a warming climate).

The question that this paradox raises is not whether global (or UK) climate will change

in the future, nor even by how much it will change. The question rather is whether on the

relatively slow time-scales that climate will change—that is, slow relative to time-scales of

political and technological change—we can adapt to such change by incorporating flexibility

and resilience into our infrastructure and regulatory planning environments. Such a challenge

will impinge on many sectors of the regulated UK economy and environment— water, land

use, transport, energy, construction, insurance, coastal management, wildlife and agriculture.

Organisations, charged with investment decisions, environmental management and the

development of future planning strategies, need to include climate in their decision-

frameworks as a key variable rather than as an assumed constant. If they do, then the twenty-

first century need not hold the prospect of major climate-induced dislocations in UK economic

activity or environmental systems.

This conclusion may not be true, however, for other world regions with a less

regulated natural and economic environment and with less investment capital available

to be directed into such adaptation objectives. As a signatory to the United Nations

Framework Convention on Climate Change therefore, the UK will need to continue to

articulate and implement climate mitigation policies both at home and abroad. This can

and should be justified on the criteria both of international social justice and of the

economic and environmental benefits to be gained from the use of more sustainable

energy technology.

Ultimately, climate, and therefore climate change, should be seen as a resource to

manage and to benefit from, and as essentially neutral. The notion of ‘good’ and ‘bad’

climates is a hard one to defend in any absolute sense. Temporal changes in climate, seen in

this way, present societies with challenges to cope with and opportunities to exploit. These

challenges and opportunities presented by temporal changes in climate are very much those

that every colonising community throughout history has realised are posed by geographical

differences in climate. This view of climate, whether implicit or explicit, has been true of,

for example, the Mongols in Europe, the Vikings in Greenland, or the Europeans in Africa.

For example, one may view the nineteenth-century history of the interaction between climate

and society as one that concerned the ability of the European colonising powers to exploit

geographical differences in climate in the Tropics—rubber in Malaysia, cocoa in West Africa

or bananas in the Caribbean—and to manage the regional climate impacts that such

exploitation might bring with it. A twenty-first century history of climate-society interaction

may well be about the ability of different communities, nations or regions to exploit and

manage the forthcoming temporal changes in climate brought about by human pollution of

the atmosphere.

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