. 9
( 16)


include the coastal systems of southern and eastern Africa. Under both the A1 and B1 scenarios, mixed
rain-fed, semi-arid systems are shown to be heavily affected by changes in climate in the Sahel. Mixed
rain-fed and highland perennial systems in the Great Lakes region in East Africa and in other parts of East
Africa are also heavily affected. In the B1 SRES scenario, which assumes development within a framework
of environmental protection, the impacts are, however, generally less, but marginal areas (e.g., the semi-
arid systems) become more marginal, with the impacts on coastal systems becoming moderate.**
• Current stress on water in many areas of Africa is likely to be enhanced by climate variability and change.
Increases in run-off in East Africa (possibly ¬‚oods) and decreases in run-off and likely increased drought
risk in other areas (e.g. southern Africa) are projected by the 2050s. Current water stresses are not only
linked to climate variations, and issues of water governance and water-basin management must also be
considered in any future assessments of water in Africa.**
• Any changes in the primary production of large lakes are likely to have important impacts on local food
supplies. For example, Lake Tanganyika currently provides 25% to 40% of animal protein intake for the
population of the surrounding countries, and climate change is likely to reduce primary production and
possible ¬sh yields by roughly 30%. The interaction of human management decisions, including over-
¬shing, is likely to further compound ¬sh offtakes from lakes.**
• Ecosystems in Africa are likely to experience major shifts and changes in species range and possible
extinctions (e.g., fynbos and succulent Karco biomes in southern Africa).*
• Mangroves and coral reefs are projected to be further degraded, with additional consequences for ¬sh-
eries and tourism.**
• Towards the end of the twenty-¬rst century, projected sea-level rise will affect low-lying coastal areas
with large populations. The cost of adaptation will exceed 5% to 10% of GDP.**

socio-economic circumstances, advances in treatment or prevention and public
health infrastructure.
The potential impact of climate change on human health could be large.
However, the factors involved are complex and quantitative conclusions require
careful study of the direct effects of climate on humans and of the epidemiology
of the diseases particularly affected. Some remarks about how the health impacts
of extremes and disasters might be reduced are given in the next section.

Adaptation to climate change
As we have seen, some of the impacts of climate change are already apparent.
A degree of adaptation63 therefore has already become a necessity. Numerous
possible adaptation options for responding to climate change have already been
identi¬ed “ examples are given in Table 7.2. Because it takes some decades for
the oceans to warm, there also exists a substantial commitment to further cli-
mate change even if carbon dioxide emissions were to be halted. Urgent action
is therefore necessary to consider the further substantial adaptation which will
be necessary.
These can reduce adverse impacts and enhance bene¬cial effects of climate
change and can also produce immediate ancillary bene¬ts, but they cannot pre-
vent all damages. Many of the options listed are presently employed to cope
with current climate variability and extremes; their expanded use can enhance
both current and future capacity to cope. But such actions may not be as effec-
tive in the future as the amount and rate of climate change increase. To make
a list of possible adaptation options is relatively easy. If they are to be applied
effectively, much more information needs to be generated regarding the detail
and the cost of their application over the wide range of circumstances where
they will be required.
Of particular importance is the requirement for adaptation to extreme
events and disasters such as ¬‚oods, droughts and severe storms.64 Vulnerability
to such events can be substantially reduced by much more adequate prepara-
tion.65 For instance, following Hurricanes George and Mitch, the Pan American
Health Organisation (PAHO) identi¬ed a range of policies to reduce the impact
of such events:66

• undertaking vulnerability studies of existing water supply and sanitation sys-
tems and ensuring that new systems are built to reduce vulnerability;
• developing and improving training programmes and information systems
for national programmes and international cooperation on emergency
218 T H E I M PAC T S O F C L I M AT E C H A N G E

• developing and testing early warning systems that should be coordinated by a
single national agency and involve vulnerable communities. Provision is also
required for providing and evaluating mental care, particularly for those who
may be especially vulnerable to the adverse psychosocial effects of disasters
(e.g. children, the elderly and the bereaved).

Table 7.2 Selected examples of planned adaptation by sector

Key constraints and
opportunities for
implementation (Normal
font = constraints;
Adaptation option/ Underlying policy
italics = opportunities)
Sector strategy framework

Financial, human resources
National water policies
Water Expanded rainwater
and physical barriers;
and integrated water
harvesting; water
integrated water resources
resources management;
storage and conservation
management; synergies
water-related hazards
techniques; water reuse;
with other sectors
desalination; water use
and irrigation ef¬ciency
Technological and ¬nancial
R&D policies; institutional
Agriculture Adjustment of planting
constraints; access to new
reform; land tenure and
dates and crop variety;
varieties; markets; longer
land reform; training;
crop relocation; improved
growing season in higher
capacity building; crop
land management, e.g.
latitudes; revenues from
insurance; ¬nancial
erosion control and soil
˜new™ products
incentives, e.g. subsidies
protection through tree
and tax credits
Financial and technological
Standards and
Relocation; seawalls and
barriers; availability of
regulations that
storm surge barriers;
relocation space; integrated
integrate climate change
dune reinforcement; land
(including coastal
policies and management;
considerations into
acquisition and creation
synergies with sustainable
design; land-use policies;
of marshlands/wetlands
development goals
building codes; insurance
as buffer against sea
level rise and ¬‚ooding;
protection of existing
natural barriers
Limits to human tolerance
Public health policies
Human health Heat-health action plans;
(vulnerable groups);
that recognise climate
emergency medical
knowledge limitations;
risk; strengthened health
services; improved
¬nancial capacity;
services; regional and
climate-sensitive disease
upgraded health services;
international cooperation
surveillance and control;
improved quality of life
safe water and improved

Table 7.2 Cont.

Key constraints and
opportunities for
implementation (Normal
font = constraints;
Adaptation option/ Underlying policy
italics = opportunities)
Sector strategy framework
Appeal/ marketing of
Integrated planning
Tourism Diversi¬cation of tourism
new attractions; ¬nancial
(e.g. carrying capacity;
attractions and revenues;
and logistical challenges;
linkages with other
shifting ski slopes to
potential adverse impact on
sectors); ¬nancial
higher altitudes and
other sectors (e.g. arti¬cial
incentives, e.g. subsidies
glaciers; arti¬cial snow-
snow-making may increase
and tax credits
energy use); revenues
from ˜new™ attractions;
involvement of wider
group of stakeholders
Financial and technological
Integrating climate
Transport Realignment/relocation;
barriers; availability of
change considerations
design standards and
less vulnerable routes;
into national transport
planning for roads, rail
Improved technologies
policy; investment in R&D
and other infrastructure
and integration with key
for special situations, e.g.
to cope with warming
sectors (e.g. energy)
permafrost areas
and drainage
Access to viable
National energy policies,
Energy Strengthening of
alternatives; ¬nancial and
regulation, and ¬scal
overhead transmission and
technological barriers;
and ¬nancial incentives
distribution infrastructure;
acceptance of new
to encourage use of
underground cabling for
technologies; stimulation
alternative sources;
utilities; energy ef¬ciency;
of new technologies; use of
incorporating climate
use of renewable sources;
local resources
change in design
reduced dependence on
single sources of energy

Note: Other examples from many sectors would include early warning systems.

Costing the impacts: extreme events
In the previous paragraphs the impacts of climate change have been
described in terms of a variety of measures; for instance, the number of peo-
ple affected (e.g. by mortality, disease or by being displaced), the gain or loss
of agricultural or forest productivity, the loss of biodiversity, the increase in
220 T H E I M PAC T S O F C L I M AT E C H A N G E

deserti¬cation, etc. However, the most widespread measure, looked for by
many policymakers, is monetary cost or bene¬t. But before describing what
has been done so far to estimate the overall costs of impacts, we need to con-
sider what is known about the cost of damage due to extreme events (such
as ¬‚oods, droughts, windstorms or tropical cyclones). As has been constantly
emphasised in this chapter these probably constitute the most important ele-
ment in climate change impacts.
Because the incidence of such extreme events has increased signi¬cantly
in recent decades, information about the cost of the damage due to them has
been tracked by insurance companies. They have catalogued both the insured
losses and, so far as they have been able to estimate, the total economic losses “
these latter have shown an approximately tenfold increase from the 1950s to
the 1990s (see Figure 1.2 and box below). Although factors other than climate
change have contributed to this increase, climate change is probably the fac-
tor of most signi¬cance. The estimates for the 1990s of annual economic losses
from weather-related disasters amount to approximately 0.2% of global world
product (GWP) and vary from about 0.3% of aggregate GDPs for the North and
Central American and the Asian regions to less than 0.1% for Africa (Table 7.3).
These average ¬gures hide big regional and temporal variations. For instance,
the annual loss in China from natural disasters from 1989 to 1996 is estimated
to range from 3% to 6% of GDP, averaging nearly 4%67 “ over ten times the world
average. The reason why the percentage for Africa is so low is not because there
are no disasters there “ Africa on the whole has more than its fair share (see box
on page 216) “ but because most of the damage in African disasters is not real-
ised in economic terms, nor does it appear in economic statistics. Further such
averaged numbers hide the severe impact of disasters on individual countries or
regions which, as we mention below with the example of Hurricane Mitch, can
prove to be very large indeed. Even for the United States, the total economic cost
of Hurricane Katrina which struck New Orleans in 2005 has been estimated at
around 1% of the United States GDP.
The percentages we have quoted are conservative in that they do not represent
all relevant costs. They relate to direct economic costs only and do not include
associated or knock-on costs of disasters. This means, for instance, that the
damage due to droughts is seriously underestimated. Droughts tend to happen
slowly and many of the losses may not be recorded or borne by those not directly
Another reason for treating the information in the box with caution is
because of the large disparities between different parts of the world and coun-
tries regarding per capita wealth, standard of living and degree of insurance
cover. For instance, probably the most damaging hurricane ever, Hurricane

Table 7.3 Fatalities, economic losses and insured losses (both in 1999 US dollars) for
disasters in different regions as estimated by the insurance industry for the period 1985“99.
The percentage from weather-related disasters (including windstorms, ¬‚oods, droughts,
wild¬re, landslides, land subsidence, avalanches, extreme temperature events, lightning,
frost and ice/snow damages) is indicated in each case. Total losses are higher than those
summarised in Figure 1.2 because of the restriction of Figure 1.2 to losses from large
catastrophic events

Africa South Asia Australia Europe World

Number of events 810 610 2 260 2 730 600 1 810 8 820
Weather-related 91% 79% 87% 78% 87% 90% 85%
Fatalities 22 990 56 080 37 910 429 920 4 400 8 210 559 510
Weather-related 88% 50% 72% 70% 95% 96% 70%
Economic losses
($US billion) 7 16 345 433 16 130 947
Weather-related 81% 73% 84% 63% 84% 89% 75%
Insured losses
($US billion) 0.8 0.8 119 22 5 40 187
Weather-related 100% 69% 86% 78% 74% 98% 87%

Mitch, which hit Central America in 1998 does not appear in Table 7.4 as the
total insured losses were less than $US1 billion. In that storm, 600 mm of rain-
fall fell in 48 hours, there were 9000 deaths and economic losses estimated at
over $US6 billion. The losses in Honduras and Nicaragua amounted to about
70% and 45% respectively of their annual gross national product (GNP). Another
example that does not appear in Table 7.4 for the same reason is the ¬‚oods in
central Europe in 1997 which caused the evacuation of 162 000 people and over
$US5 billion of economic damage.
How about the likely costs of extreme events in the future? To estimate those
we need much more quantitative information about their likely future inci-
dence and intensity. In Chapter 6, an estimate of a factor of 5 was quoted for
the likely increase of the risk of ¬‚oods by mid twenty-¬rst century (Figure 6.11).
A speculative but probably conservative calculation of a global average ¬gure
for the future might be obtained as follows. Beginning with the 0.2% or 0.3% of
GDP from the insurance companies™ estimate of the current average costs due to
222 T H E I M PAC T S O F C L I M AT E C H A N G E

The insurance industry and climate change
The impact of climate on the insurance industry is mainly through extreme weather events. In developing
countries there may be very high mortality from extreme weather but relatively small costs to the indus-
try because of low insurance penetration. In developed countries the loss of life may be much less but the
costs to the insurance industry can be very large. Figure 1.2 illustrates the large growth in weather-related
disasters and the associated economic and insured losses since the 1950s and Table 7.3 the distribution of
the disasters, fatalities and economic losses from 1985 to 1999 around the continents. Some idea of the
types of disaster that cause the largest economic loss can be gleaned from Table 7.4.
Part of the observed upward trend in historical disaster losses is linked to socio-economic factors such
as population growth, increased wealth and urbanisation in vulnerable areas; part is linked to climatic
factors such as changes in precipitation, ¬‚ooding and drought events. There are differences in balance
between the causes by region and type of event. Because of the complexities involved in delineating both
the socio-economic and the climatic factors, the proportion of the contribution from human-induced

Table 7.4 Individual events included in the aggregates in Table 7.3 that incurred over $US5
billion of economic loss and over $US1 billion of insured loss

Economic losses Ratio: insured/
Year Event Area (billion $US) economic losses

1995 Earthquake Japan 112.1 0.03
1994 Northridge Earthquake USA 50.6 0.35
1992 Hurricane Andrew USA 36.6 0.57
1998 Floods China 30.9 0.03
1993 Floods USA 18.6 0.06
1991 Typhoon Mireille Japan 12.7 0.54
1989 Hurricane Hugo Caribbean, 12.7 0.50
1999 Winterstorm Lothar Europe 11.1 0.53
1998 Hurricane Georges Caribbean, 10.3 0.34
1990 Winterstorm Daria Europe 9.1 0.75
1993 Blizzard USA 5.8 0.34
1996 Hurricane Fran USA 5.7 0.32
1987 Winterstorm W. Europe 5.6 0.84
1999 Typhoon Bart Japan 5.0 0.60

climate change cannot be de¬ned with any certainty “ although it is interesting to note that the growth
rate in damage cost of weather-related events was three times that of non-weather-related events for the
period 1960“99.
Recent history has shown that weather-related losses can stress insurers to the point of bankruptcy.
Hurricane Andrew in 1992 broke the $US20 billion barrier for insured loss and served as a wake-up call to
the industry. Hurricane Katrina in 2005 that had been a Category 5 storm but weakened to a Category 3
before landfall caused a storm surge, supplemented by waves that reached around 5 m above sea level in
the city of New Orleans, overtopping and breaching sections of the city™s sea defences, ¬‚ooding 70“80%
of New Orleans. Well over 1000 people died, private insurance claims in excess of $US40 billion were
made and total economic losses are estimated to be over $US100 billion or around 1% of US annual
GDP.69 Katrina was the costliest hurricane ever in terms of economic damage. Other records regarding
Atlantic hurricanes were also broken in 2005,70 the most hurricanes (13), strongest ever (Wilma) and
costliest in total ($US200 billion +).
As a result of such events, in many ¬‚ood-prone areas insurance premiums have risen dramatically and
for many properties insurance ¬‚ood cover has been withdrawn. In order to formulate their future busi-
ness policy, the insurance industry is actively studying likely future trends in the incidence of disasters due
to climate change along with related socio-economic trends in both the developed and the developing

weather-related extreme events, then multiplying by two to allow for the factors
mentioned above (e.g. associated or knock-on costs) and further multiplying by
four to allow for the likely increase in extreme events, say by the middle of the
twenty-¬rst century, we end up with a ¬gure of about 2% of GDP. This can be
compared with an estimate of 0.5“1% in the Stern Review on the economics of
climate change of 2006,68 where a much smaller increase was assumed in the
risk of extreme events. However the Stern Review emphasises that a steeper
rise is likely later in the century because of the steep rise in the incidence of
extremes as global average temperature increases even more. Further, my esti-
mate here and those in the Stern review are ˜money™ estimates made in the
context of developed countries™ economies. As the Stern Review also points out,
the real total costs of extreme events taking into account all damages (includ-
ing those that cannot be expressed in money terms) are likely to be very much
larger especially in many developing countries.

Costing the total impacts
We now turn to consider all the impacts of anthropogenic climate change,
attempts that have been made to express their cost in monetary terms and the
224 T H E I M PAC T S O F C L I M AT E C H A N G E

validity of the methods employed. The IPCC 1995 Report contained a review
of four cost studies71 of the impacts of climate change in a world where the
atmospheric carbon dioxide concentration had doubled from its pre-industrial
level,72 the most detailed studies being carried out for the United States. For
those impacts against which some value of damage can be placed, estimates fell
in the range of 1.0% to 1.5% of the US GDP in 1990. For other countries in the
developed world, estimates of the cost of impacts in terms of percentage of GDP
were similar. For the developing world, estimates of annual cost were typically
around 5% of GDP (with a range of from 2% to 9% of GDP). These studies provided
the ¬rst indication of the scale of the problem in economic terms. However, as
the authors of these economic studies explain, their estimates were crude, were
based on very broad assumptions, were mostly calculated in terms of the impact
on today™s economies rather than future ones and should not be considered as
precise values.
Modelling the monetary impacts of climate change requires quantitative
analysis connecting environmental, economic and social issues. The main tool
for such studies is the Integrated Assessment Model (IAM) (see box in Chapter 9
on page 280) which includes all the elements illustrated in Figure 1.5. The Stern
Review73 has reviewed recent work employing such models pointing out the
elements that need to be included in making cost estimates, in particular adap-
tation (which provides large potential for damage reduction but the cost of adap-
tation must be added), damage from extreme events (omitted in most studies to
date) and non-market impacts (e.g. mortality from diseases, heat and cold stress,
etc. omitted in many studies).
Adaptation is especially important in the agricultural sector.74 In that sec-
tor, under changes in global average temperature of less than about 3 °C, when
adaptation is taken into account, estimates of global aggregate economic impact
cost vary from the slightly negative (i.e. slightly bene¬cial) to the moderately
positive depending on underlying assumptions (see also Section ˜Impact on agri-
culture and food supply™, pages 196“202). However, these studies have largely
ignored the increasing in¬‚uence of climate extremes and as yet inadequately
considered important factors such as water availability “ largely because of the
lack of detailed information regarding these.
Further, the aggregate hides large regional differences. Bene¬cial effects
are expected predominantly at mid to high latitudes in the developed world
especially where increased temperatures may bring longer growing seasons.
Strongly negative effects are expected for populations at lower latitudes where
any increase in average temperature or in dryness brings lower crop yields,
where there is less capacity to adapt (e.g. because of lack of infrastructure, capi-
tal or education) or where there are poorer connections to regional and global

Only the rectangular support pillars that once held up the Highway 90 bridge spanning Biloxi Bay remained
standing after Hurricane Katrina battered the Mississippi shoreline. The image shows widespread destruction
along the shoreline, with only white foundations where buildings and homes once stood in some places. The
Ikonos satellite captured this image on 2 September 2005, four days after Katrina came ashore.

trading systems. Overall, climate change will tend to tip agriculture production
in favour of rich and well-fed regions at the expense of poorer and less well-fed
For global average temperature increases of 2“3 °C from pre-industrial lev-
els (i.e. up to a situation of doubled carbon dioxide concentration) which are
expected to occur by early in the second half of the twenty-¬rst century, the
Stern Review has reviewed recent estimates and concluded that the cost of cli-
mate change could be equivalent to a loss of 0 to 3% in global GDP from what
could have been achieved in a world without climate change.76 The Stern Review
goes on to point out that poor countries will suffer higher costs. Further, as
226 T H E I M PAC T S O F C L I M AT E C H A N G E

A US Coast Guardsman searches for survivors in New Orleans in the aftermath of Hurricane Katrina.

we saw in the last section I consider that the Stern Review has underestimated
the likely cost of extreme events perhaps by a factor of two. Taking these into
account would result in estimates of, say 1% to 4% loss of global GDP in devel-
oped countries and much greater loss of 5% or even 10% or more in many devel-
oping countries.
Two important factors have been omitted from the ¬gures just cited. The
¬rst is that impacts cannot be quanti¬ed in terms of monetary cost alone. For
instance, the loss of life (see Question 7), human amenity, natural amenity or
the loss of species cannot be easily expressed in money terms. This can be illus-
trated by focusing on those who are likely to be particularly disadvantaged by
global warming. Most of them will be in the developing world at around the
subsistence level. They will ¬nd their land is no longer able to sustain them
because it has been lost either to sea level rise or to extended drought. They
will therefore wish to migrate and will become environmental refugees. It has
been estimated that, under a business-as-usual scenario, the total number of
persons displaced by the impacts of global warming could total of the order of
150 million by the year 2050 (or about 3 million per year on average) “ about

Estimates of impacts costs under business-as-usual (BAU) from the
Stern Review
Using the PAGE 2002 Integrated Assessment Model (IAM),75 the Stern Review considers estimates of
cost to the world™s economies over the next two centuries if emissions of greenhouse gases continue on a
˜business-as-usual™ (BAU) path taking global average temperature increases possibly to 4 °C by 2100 (cf.
Figure 6.4) and 8 °C by 2200. It is pointed out that modelling over many decades, regions and possible
outcomes demands that distributional and ethical judgements are made systematically and explicitly, and
that model results have to be treated with appropriate caution. Stern expresses the expected loss of future
welfare due to climate change in terms of the future consumption that is forecast to occur with climate
change compared with what would occur in the absence of climate change. It is explained that ˜costs
measured in this way are like a tax levied on consumption now and for ever, the proceeds of which are
simply poured away™.
Stern presents the results from his modelling work as follows.80

• Under a basic calculation, the total cost of BAU climate change is estimated to equate to an average
reduction in global per capita consumption of 5%, at a minimum, now and for ever. However, this cal-
culation omitted three important factors as follows.
• Firstly, when direct impacts on the environment and human health (non-market impacts) are included,
increases in the total cost of BAU climate change rise from 5% to 11%, although valuations here raise
dif¬cult ethical and measurement issues. But this does not fully include ˜socially contingent™ impacts
such as social and political instability, which are very dif¬cult to measure in monetary terms.
• Secondly, if climate feedbacks are taken into account, the projected increases in global average tempera-
ture would tend to the higher end of the range (see Chapter 6, page 143“6) and the estimated costs
for BAU climate change could increase from 5% to 7% or from 11% to 14% if non-market impacts are
• Thirdly, a disproportionate burden of climate change impacts falls on poor regions of the world. Giving
this burden stronger relative weight could increase the cost of BAU climate change by more than one-

Putting all these factors together increases the total cost of BAU climate change to the equivalent of
around a 20% reduction in current per capita consumption now and for ever. Distributional judgements, a
concern with living standards beyond those elements re¬‚ected in GDP and modern approaches to uncer-
tainty all suggest that the appropriate estimate of damages may well lie in the upper part of the range
5“20%. Much but not all of that loss could be avoided through a strong mitigation policy. It is argued in
later chapters of the Stern Review that this can be achieved at lower cost.
228 T H E I M PAC T S O F C L I M AT E C H A N G E

100 million due to sea level rise and coastal ¬‚ooding and about 50 million due
to the dislocation of agricultural production mainly due to the incidence and
location of areas of drought.78 The cost of resettling 3 million displaced persons
per year (assuming that is possible) has been estimated at between $US1000 and
$US5000 per person, giving a total of about $US10 000 million per year.79 What
the estimated cost for resettlement does not include, however (as the authors
of the study themselves emphasise), is the human cost associated with displace-
ment. Nor does it include the social and political instabilities that ensue when
substantial populations are seriously disrupted because their means of liveli-
hood has disappeared. The effects of these could be very large.
The second factor not being taken into account in the above estimates of total
cost is the in¬‚uence of the longer term “ they only concern climate change
impacts up to about the middle of the twenty-¬rst century under the possibility
of a doubling of equivalent carbon dioxide concentration. Soon after the end of
the twenty-¬rst century, under the scenarios with higher carbon dioxide emis-
sions (in other words, if strong action is not taken to curb emissions), a further
doubling of the equivalent carbon dioxide concentration will have occurred and
it will be continuing to rise. The impacts of the additional climate change that
would occur with a second effective doubling of carbon dioxide will be sub-
stantially more severe than those of the ¬rst doubling.80 The Stern Review has
considered these (see box) and estimated that the total cost of business-as-usual
(BAU) climate change to be equivalent to around a 5“20% reduction in current
global per capita consumption now and for ever, with a strong likelihood that it
will be in the upper part of that range and with disproportionate losses tending
to fall on poorer countries.
Impacts that may be a century away may not easily claim our attention.
However, because of the long lifetime of some greenhouse gases, because of the
long memory of the climate system, because some of the impacts may turn out
to be irreversible and also because of the time taken for human activities and
ecosystems to respond and change course, it is important to have an eye on the
longer term. Looking at the longer term also raises for consideration the pos-
sibility of what are often called ˜singular events™ or irreversible events of large
or unknown impact. Some of these have been mentioned earlier in this chapter
or in previous chapters. Examples are given in Table 7.5. It is clearly dif¬cult to
provide quantitative estimates of the probability of such events. Nevertheless
it is important that they are not ignored. One recent study81 has allocated a
potential damage cost to these of about 1% of GWP for a warming of 2.5 °C and
about 7% of GWP for a warming of 6 °C. Such calculations are necessarily based
on highly speculative assumptions, but in that particular study these singular
events represent the largest single contributor to the total overall cost.

Table 7.5 Examples of singular non-linear events and their impactsa

Singularity Causal process Impacts

Consequences for marine ecosystems
Changes in thermal and freshwater
Non-linear response
and ¬sheries could be severe.
forcing could result in complete
of thermohaline
Complete shutdown would lead to a
shutdown of North Atlantic THC or
circulation (THC)
stagnant deep ocean, with reducing
regional shutdown in the Labrador
deepwater oxygen levels and carbon
and Greenland Seas. In the Southern
uptake, affecting marine ecosystems. It
Ocean, formation of Antarctic
would also represent a major change in
bottom water could shut down.
heat budget and climate of northwest
Such events are simulated by models
and also found in the palaeoclimatic
Considerable and rapid sea level rise
WAIS may be vulnerable to climate
Disintegration of West
would widely exceed adaptive capacity
change because it is grounded below
Antarctic Ice Sheet
for most coastal structures and
sea level. Its disintegration could raise
global sea level by 4 to 6 m. Large sea
level rise from this cause is unlikely
during the twenty-¬rst century.
Positive feedbacks in Climate change could reduce the Rapid, largely uncontrollable increases
the carbon cycle ef¬ciency of current oceanic and in atmospheric carbon concentrations
biospheric carbon sinks. Under and subsequent climate change would
some conditions the biosphere could increase all impact levels and strongly
become a source.b limit adaptation possibilities.
Gas hydrate reservoirs also may be
destabilised, releasing large amounts
of methane to the atmosphere.
This could have severe social effects,
Climate change “ alone or
Destabilisation of
which, in turn, may cause several
in combination with other
international order by
types of con¬‚ict, including scarcity
environmental pressures “ may
environmental refugees
disputes between countries, clashes
exacerbate resource scarcities in
and emergence of
between ethnic groups and civil strife
developing countries. These effects
con¬‚icts as a result of
and insurgency, each with potentially
are thought to be highly non-linear,
multiple climate change
serious repercussions for the security
with potential to exceed critical
interests of the developed world.
thresholds along each branch of the
causal chain.

For recent comment see Frequently Asked Questions 10.2 in Solomon et al. (eds.) Climate Change 2007:
the Physical Science Basis. pp. 818“19.
See box on climate carbon/cycle feedbacks in Chapter 3, pages 48“9.
230 T H E I M PAC T S O F C L I M AT E C H A N G E

Table 7.6 Examples of impacts due to changes in extreme weather and climate eventsb

Examples of major projected impacts
Likelihood of future trends based
by sector
Phenomenon and direction on projections for twenty-¬rst
of trend century using SRES scenarios Agriculture, forestry and ecosystems

Virtually certaina
Over most land areas, Increased yields in colder
warmer and fewer cold days environments; decreased yields in
and nights, warmer and more warmer environments; increased
frequent hot days and nights insect outbreaks

Very likely Reduced yields in warmer regions
Warm spells/heatwaves.
due to heat stress; increased danger
Frequency increases over
of wild¬re
most land areas

Very likely Damage to crops; soil erosion,
Heavy precipitation events.
inability to cultivate land due to
Frequency increases over
waterlogging of soils
most areas

Area affected by drought Likely Land degradation; lower yields/
increases crop damage and failure; increased
livestock deaths; increased risk of
Intense tropical cyclone Likely Damage to crops; windthrow
activity increases (uprooting) of trees; damage to
coral reefs

Increased incidence of Salinisation of irrigation water,
extreme high sea level estuaries and fresh-water systems
(excludes tsunamis)c

See Note 1, Chapter 4 for further details regarding de¬nitions.
These examples do not take into account developments in adaptive capacity.

Table 7.6

Water resources Human health Industry, settlement and society

Reduced human mortality from Reduced energy demand for heating;
Effects on water
decreased cold exposure increased demand for cooling; declining
resources relying on
air quality in cities; reduced disruption to
snow melt; effects on
transport due to snow, ice; effects on winter
some water supplies
Reduction in quality of life for people in
Increased risk of heat-related
Increased water
warm areas without appropriate housing;
mortality, especially for the
demand; water quality
impacts on the elderly, very young and poor
elderly, chronically sick, very
problems, e.g. algal
young and socially isolated
Disruption of settlements, commerce,
Increased risk of deaths, injuries
Adverse effects on
transport and societies due to ¬‚ooding;
and infectious, respiratory and
quality of surface
pressures on urban and rural infrastructures;
skin diseases
and groundwater;
loss of property
contamination of water
supply; water scarcity
may be relieved
Water shortage for settlements, industry
More widespread water Increased risk of food and water
and societies; reduced hydropower
stress shortage; increased risk of
generation potentials; potential for
malnutrition; increased risk of
population migration
water- and food borne diseases
Disruption by ¬‚ood and high winds;
Increased risk of deaths,
Power outages causing
withdrawal of risk coverage in vulnerable
injuries, water- and food- borne
disruption of public
areas by private insurers; potential for
diseases; post-traumatic stress
water supply
population migrations; loss of property
Costs of coastal protection versus costs of
Increased risk of deaths and
Decreased fresh-water
land-use relocation; potential for movement
injuries by drowning in ¬‚oods;
availability due to salt
of populations and infrastructure; also see
migration-related health effects
water intrusion
tropical cyclones above

Extreme high sea level depends on average sea level and on regional weather systems. It is de¬ned as the
highest 1% of hourly values of observed sea level at a station for a given reference period.
In all scenarios, the projected global average sea level at 2100 is higher than in the reference period.
The effect of changes in regional weather systems on sea level extremes has not been assessed.
232 T H E I M PAC T S O F C L I M AT E C H A N G E


• The main impacts of climate change will be due to sea level rise, increases in
temperature and heat waves and a more intense hydrological cycle leading
on average to more frequent and intense ¬‚oods, droughts and storms (see
Table 7.6 for a summary of impacts of extreme events).
• There are many ways in which the environment is being degraded due
to human activities, for instance, through over-withdrawal of ground-
water, loss of soil or deforestation. Global warming will exacerbate these
• To respond to climate change impacts, it will be necessary to adapt. In
many cases this will involve changes in infrastructure, for instance new sea
defences or water supplies. Many of the impacts of climate change will be
adverse, but even when the impacts in the long term turn out to be bene¬-
cial, in the short term the process of adaptation will mostly have a negative
impact and involve cost.
• Through adaptation to different crops and practices, ¬rst indications are
that the total of world food production may not be seriously affected by
climate change “ although studies have not yet taken into account the
likely occurrence of climate extremes. However, the combination of popula-
tion growth and climate change will mean that disparity in per capita food
supplies between the developed and the developing world will become
much larger.
• Because of the likely rate of climate change, there will also be a serious
impact on natural ecosystems, especially at mid to high latitudes. Forests
especially will be affected by increased climate stress causing substantial
dieback and loss of production, associated with which there is the positive
feedback of additional carbon dioxide emissions. In a warmer world longer
periods of heat stress will have an effect on human health; warmer tem-
peratures will also encourage the spread of certain tropical diseases, such as
malaria, to new areas.
• Economists have attempted to estimate the average annual cost in mon-
etary terms of the impacts that would arise under the climate change due
to a doubling of pre-industrial atmospheric carbon dioxide concentration.
If allowance is added for the impact of extreme events, the estimates are
typically around 1% to 4% of GDP for developed countries and 5“10 %
or more for many developing countries. Later chapters will compare them
with the cost of taking action to slow the onset of global warming or reduce

its overall magnitude. However, these attempts at monetary costing only
represent a part of the overall impact story that must include the cost in
human terms, for instance, the large social and political disruption some of
the impacts will bring. In particular, it is estimated that there could be up to
3 million new environmental refugees each year or over 150 million by the
middle of the twenty-¬rst century. Re¬nements of all these estimates and
the assumptions on which they are based are urgently required.
• Estimates of overall impact need to take the longer term into account. The
cost of continuing with business-as-usual (BAU) has been estimated by the
Stern Review as the equivalent of 5“20% reduction in per capita consump-
tion now and for ever with a strong likelihood that it will be in the upper part
of that range and with disproportionate losses falling on poorer countries.
However, many will ask why we should be concerned about the state of
the Earth so far ahead in the future. Can we not leave it to be looked after
by future generations? The next chapter will give something of my personal
motivation for caring about what happens to the Earth in the future as well
as now.

1 For your local region, ¬nd out about its water supply and how the water is
used (e.g. by domestic users, agriculture, industry, etc.). What are likely to be
the trends in its use over the next 50 years due, for instance, to population
changes or changes in agriculture or industry? What are the possibilities for
increased supply and how might these be affected by climate change?
2 For your local area, ¬nd out about current environmental problems such as
sea level rise due to subsidence, over-use of groundwater and air pollution
affecting forests. Which of these are likely to be exacerbated by climate
change? Try to estimate by how much.
3 For your local region, identify the possible impacts of climate change over
the next 100 years and quantify them as far as you can. Attempt to make an
estimate of the cost of the damage for each impact. How far could adapta-
tion reduce each type of damage?
4 From the information in Chapter 6, make estimates of possible climate
change by the middle of the next century for typical regions of boreal forest.
Then estimate from Figure 7.16 for each of the three tree species what loss of
productivity might occur in each case.
234 T H E I M PAC T S O F C L I M AT E C H A N G E

5 Make an estimate of the total volume of ice in the Greenland and Antarctic
ice caps. What proportion would have to melt to increase the sea level by
the 6 metres or so which occurred during the last interglacial period?
6 In the past, human communities have adapted to changes of many kinds includ-
ing some changes in climate. It is sometimes argued that, because the adaptabil-
ity of human beings is not fully allowed for, the likely damage from the impacts
of climate change in the future tends to be overestimated. Do you agree?
7 In economic cost“bene¬t analyses, it is often necessary to attach a value to
a ˜statistical life™.81 It is not human life itself that is being valued but a change
in the risk of death averaged over a population of human beings. One way
of attempting this valuation is to consider a person as an economic agent
capable of producing economic output. However, the preferred approach is
to value a statistical life on the basis of what individuals are willing to pay or
accept for changes in the risk of death. This approach tends to produce very
different money values between developed countries and developing coun-
tries. Do you think this is defensible? Give up to ¬ve examples of the analysis
of particular environmental problems for which you think it would be useful
to include the valuation of a statistical human life. Look for values that have
been attributed in different circumstances. Do questions of equity have any
relevance in your examples?
8 Increasing demand for biofuels substituting for gasoline or diesel for trans-
port is leading to increasing use of land for biofuel crops. Find out how much
land might be needed and the degree of competition with other crops (e.g.
food or forests) and suggest how sustainable land use can be promoted.

Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K. B., Tignor, M.,
Miller, H. L. (eds.) 2007: Climate Change 2007, The Physical Science Basis,
Contribution of Working Group I to the Fourth Assessment Report of the
Intergovernmental Panel on Climate Change. Cambridge: Cambridge University
Technical Summary (summarises the basic science and climate projections)
Chapter 10 Global climate projections (including temperature, precipitation and sea level)
Chapter 11 Regional climate projections
Parry, M., Canziani, O., Palutikof, J., van der Linden, P., Hanson, C. (eds.) 2007. Climate
Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working
Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate
Change. Cambridge: Cambridge University Press.
Technical Summary
N OT E S F O R C H A P T E R 7

Chapter 3 Fresh water resources
Chapter 4 Ecosystems
Chapter 5 Food, ¬bre and forest products
Chapter 6 Coastal systems and low-lying areas
Chapter 7 Industry, settlement and society
Chapter 8 Human health
Chapters 9 to 16 Impacts on different world regions
Chapter 17 Adaptation practices
Chapter 19 Key vulnerabilities and risk
Chapter 20 Climate change and sustainability
Cross-chapter case studies: C1 The impact of the European 2003 heatwave; C2
Impacts of climate change on coral reefs; C3 Megadeltas: their vulnerabilities to
climate change; C4 Indigenous knowledge for adaptation to climate change.
Schellnhuber, H. J., Cranmer, W., Nakicenovic, N., Wigley, T. Yohe, G. 2006. Avoiding
Dangerous Climate Change. Cambridge: Cambridge University Press. Contributions
to a conference on impacts, vulnerabilities, adaptations and solutions.
World Resources Institute www.wri.org. Valuable for its catalogue of climate data (e.g.
greenhouse gas emissions)
UNEP 2007, Global Environmental Outlook (GEO-4) “ a comprehensive assessment and
catalogue of environmental degradation.

1 For comprehensive detail about climate change 7 Hansen, J. et al. 2007. Climate change and trace
impacts, see Parry et al. (eds.) Climate Change 2007: gases. Philosophical Transactions of the Royal Society A,
Impacts. 365, 1925“54.
2 From Summary for policymakers in, McCarthy, J. J., 8 Pfeffer, W. T., Harper, J. T., O™Neel, S. 2008. Science,
Canziani, O., Leavy, N. A., Dotten, D. J., White, K. S. 321, 1340“3.
(eds.) 2001. Climate Change 2001: Impacts, Adaptation and 9 Witze, A. 2008. Nature, 452, 798“802.
Vulnerability. Contribution of Working Group II to the Third 10 Lowe and Gregory 2006.
Assessment Report of the Intergovernmental Panel on Climate 11 More detailed information is available in Nicholls,
Change. Cambridge: Cambridge University Press; see R. J., Wong, P. P., et al. Coastal systems and low-lying
also Parry et al. (eds.) Climate Change 2007: Impacts. areas, Chapter 6, in Parry et al. (eds.) Climate Change
3 See, for instance, Global Environmental Outlook GE04 2007: Impacts.
(UNEP Report). 2007. Nairobi, Kenya; UNEP. See also 12 Ibid., Cross-Chapter case studies, C3 Megadeltas.
Goudie, A. 2000. The Human Impact on the Natural 13 For a comprehensive account of the impact of
Environment, ¬fth edition. Cambridge, Mass: MIT Press. climate change on Bangladesh see Warrick, R. A.,
4 Bindoff, N., Willebrand, J. et al. Observations: Oceanic Ahmad, Q. K. (eds.) 1996. The Implications of Climate and
climate change and sea level, Chapter 5, in Parry et al. Sea Level Change for Bangladesh. Dordrecht: Kluwer.
(eds.) Climate Change 2007: Impacts. 14 Nicholls, R. J., Mimura, N. 1998. Regional issues
5 Lowe, J. A. Gregory, J. M. 2006. Journal of Geophysical raised by sea level rise and their policy implications.
Research, 111, C11014, doi:10.1029/2005JC003421. Climate Research, 11, 5“18.
6 Christoffersen, P., Hambrey, M. J. 2006. Is the 15 Broadus, J. M. 1993. Possible impacts of, and
Greenland ice sheet in a state of collapse? Geology adjustments to, sea-level rise: the case of
Today, 22, 98“103. Bangladesh and Egypt. In Warrick, R. A.,
236 T H E I M PAC T S O F C L I M AT E C H A N G E

Barrow, E. M., Wigley, T. M. L. (eds.) 1993. Climate 25 McLean, R. F., Tsyban, A. et al. 2001. Coastal zones
and Sea -Level Change: Observations, Projections and and marine ecosystems. In McCarthy et al., (eds.)
Implications. Cambridge: Cambridge University Climate Change 2001: Impacts, Chapter 6.
Press, pp. 263“75. Note that, because of variations 26 From Figure 3.6 in Watson, R. and the Core Writing
in the ocean structure, sea-level rise would not be Team (eds.) 2001. Climate Change 2001: Synthesis Report.
the same everywhere. In Bangladesh it would be Contribution of Working Groups I, II and III to the Third
somewhat above average (see Gregory, J. M. 1993. Sea Assessment Report of the Intergovernmental Panel on Climate
level changes under increasing CO2 in a transient Change. Cambridge: Cambridge University Press.
coupled ocean“atmosphere experiment. Journal of 27 See Table 11.8 from Shiklomanov, I. A., Rodda, J. C.
Climate, 6, 2247“62). (eds.) 2003. World Water Resources at the Beginning
16 See Chapter 4 in Warrick and Ahmad (eds.) The of the Twenty-¬rst Century. Cambridge: Cambridge
Implications of Climate and Sea Level Change. University Press.
17 Broadus, in Warrick et al. (eds.) Climate and Sea-Level 28 Kundzewicz, Z. W. Mata, L. J. et al., Fresh water
Change, pp. 263“75. resources and their management. Chapter 3, in
18 Milliman, J. D. 1989. Environmental and economic Parry et al. (eds.) Climate Change 2007: Impacts.
implications of rising sea level and subsiding deltas: 29 Quoted by Geoffrey Lean in ˜Troubled waters™, in the
the Nile and Bangladeshi examples. Ambio, 18, colour supplement to the Observer newspaper, 4 July
340“5. 1993.
19 From a report entitled Climate Change due to the 30 Betts, R. A. et al. 2007, Nature, 448, 1037“41.
Greenhouse Effect and its Implications for China. 1992. 31 All but the last are items of high con¬dence or very
Gland, Switzerland: Worldwide Fund for Nature. high con¬dence from a list in Box TS.5, p. 44 in
20 Day, J. W. et al. 1993. Impacts of sea-level rise on the Technical Summary of Parry et al. (eds.) Climate
coastal systems with special emphasis on the Change 2007: Impacts.
Mississippi river deltaic plain. In Warrick et al. (eds.) 32 Ibid., Table 3.5, in Chapter 3.
Climate and Sea-Level Change, pp. 276“96. 33 Waggoner, P. E. 1990. Climate Change and US Water
21 Clayton, K. M. 1993. Adjustment to greenhouse gas Resources. New York: Wiley.
induced sea-level rise on the Norfolk coast: a case 34 See UNCCD website: www.unccd.int/.
study. In Warrick et al. (eds.) Climate and Sea-Level 35 Sol©, R. 2007. Nature, 449, 151“3.
Change, pp. 310“21. 36 Crosson, P. R., Rosenberg, N. J. 1989. Strategies for
22 Nicholls, R. J., Mimura, N. 1998. Regional agriculture. Scienti¬c American, 261, September,
issues raised by sea-level rise and their policy pp. 78“85.
implications. Climate Research, 11, 5“18. See also 37 Easterling, W., Aggarwal, P. et al., Executive
de Ronde, J. G. 1993. What will happen to the summary, Chapter 5, in Parry et al. (eds.) Climate
Netherlands if sea-level rise accelerates? In Warrick Change 2007: Impacts.
et al. (eds.) Climate and Sea-Level Change, pp. 322“35. 38 Information in proposal for an International
23 See Nurse, L., Sem, G. et al. 2001. Small island states. Research Institute for Climate Prediction. Report
Chapter 17, in McCarthy et al., (eds.) Climate Change by Moura, A. D. (ed.) 1992. Prepared for the
2001: Impacts. International Board for the TOGA project. Geneva:
24 Bijlsma, L. 1996. Coastal zones and small islands. World Meteorological Organization.
In Watson, R. T., Zinyowera, M. C., Moss, R. H. (eds.) 39 See recent study by Battisti D. S. and R. L. Naylor,
1996. Climate Change 1995: Impacts, Adaptations 2009, Science, 323, 240“4.
and Mitigation of Climate Change: Scienti¬c“Technical 40 Reilly, J. et al. 1996. Agriculture in a changing
Analyses. Contribution of Working Group II to the Second climate. Chapter 13, in Watson et al. (eds.) Climate
Assessment Report of the Intergovernmental Panel on Change 1995: Impacts.
Climate Change. Cambridge: Cambridge University 41 Easterling, W., Aggarwal, P. et al. Chapter 5, in Parry
Press, Chapter 9. et al. (eds.) Climate Change 2007: Impacts.
N OT E S F O R C H A P T E R 7

IPCC Impacts Assessment. Canberra: Australian
42 Stafford, N. 2007. Nature, 448, 526“8.
Government Publishing Service, pp. 6“20. Although
43 Easterling, W., Aggarwal, P. et al., Chapter 5, in Parry
made in 1990 this statement remains true in 2007.
et al. (eds.) Climate Change 2007: Impacts.
54 Sale, P. F. 1999. Nature, 397, 25“7. More information
44 See Global Environmental Outlook 3 (UNEP Report).
regarding diversity in corals available on World
2002. London: Earthscan, pp. 63“5; also Global
Resources Institute website: www.wri.org/wri/marine.
Environmental Outlook 4 (GEO 4). 2007. Nairobi, Kenya:
55 More information about impact on corals in special
UNEP, p. 95
section on corals, pp. 850“7, in Parry et al. (eds.)
45 Parry, M. et al. 1999. Climate change and world food
Climate Change 2007: Impacts.
security: a new assessment. Global Environmental
56 Turley, C. et al. 2006. Reviewing the impact of
Change, 9, S51“S67.
increased atmospheric CO2 on oceanic pH and the
46 From Watson et al. (eds.) Climate Change 2001:
marine ecosystem. In Schellnhuber, H. J. (ed.) Avoiding
Synthesis Report, paragraph 5.17.
Dangerous Climate Change. pp. 65“70.
47 Miko, U. F. et al. 1996. Climate change impacts on
57 Fischlin, A., Midgley, G. F. et al. Chapter 4, p. 213 in
forests. Chapter 1, in Watson et al., (eds.) Climate
Parry et al. (eds.) Climate Change 2007: Impacts.
Change 1995: Impacts. See also Gitay, H. et al. 2001.
58 Kalkstein, I. S. 1993. Direct impact in cities. Lancet,
Ecosystems and their goods and services. Chapter 5,
342, 1397“9.
Section 5.6.3, in McCarthy et al. (eds.) Climate Change
59 Information on India from Dr Rajendra K. Pachauri,
2001: Impacts.
Tata Energy Research Institute. Information
48 Gates, D. M. 1993. Climate Change and Its Biological
regarding Europe from World Meterological
Consequences. Sunderland, Mass.: Sinauer Associates
Organization, Geneva.
Inc., p. 77.
60 Nicholls, N. 1993. El Ni±o“Southern Oscillation
49 Cox, P. M. et al. 2004. Amazon dieback under climate-
and vector-borne disease. Lancet, 342, 1284“5.
carbon cycle projections for the twenty-¬rst century.
The El Ni±o cycle is described in Chapter 5.
Theoretical and Applied Climatology, 78, 137“56.
61 This statement taken from the summary for
50 Melillo, J. M. et al. 1996. Terrestrial biotic responses
policymakers, Chapter 9, in Parry et al. (eds.) Climate
to environmental change and feedbacks to climate.
Change 2007: Impacts.
Chapter 9, in Houghton, J. T., Meira Filho, L. G.,
62 Bulleted list from Box TS6, ibid., Technical
Callander, B. A., Harris, N., Kattenberg, A.,
Summary. Meaning of asterisks: *** very high
Maskell, K. (eds.) Climate Change 1995: The Science of
con¬dence (over 90% chance of being correct),
Climate Change. Cambridge: Cambridge University
** high con¬dence (about 80% chance), * medium
Press. See also Miko, U. F. et al. 1996. Climate change
con¬dence (about 50% chance).
impacts on forests. Chapter 1, in Watson et al. (eds.)
63 For a fuller discussion on adaptation see section
Climate Change 1995: Impacts.
20.8, ibid.
51 Gitay, H. et al. 2001. Ecosystems and their goods
64 See Global Environmental Outlook 3 (UNEP Report). 2002.
and services. Technical Summary, Section 4.3, in
London: Earthscan, pp. 274“5.
McCarthy et al. (eds.) Climate Change 2001: Impacts.
65 As an example of progress with respect to disaster
52 Detail in Summary for policymakers, in Watson et al.
preparedness, the International Red Cross has
(eds.) Climate Change 2001: Synthesis Report, pp. 68“69,
formed a Climate Change Unit based in the
paragraph 3.18. Myers, N. et al. 2000. Nature, 403,
853“8 has proposed concentrating conservation effort
66 PAHO Report 1999 Conclusions and
in selected places with exceptional concentrations
Recommendations: Meeting on Revaluation of
of biodiversity. For the problems of estimating the
Preparedness and Response to Hurricanes George
effects of global warming on biodiversity see Botkin,
and Mitch, quoted in McMichael, A. et al. 2001.
D. B. et al. 2007. BioScience, 57, 227“36.
Human health. Chapter 9, in McCarthy et al. (eds.)
53 From Tegart, W. J., McG. Sheldon, G. W.,
Climate Change 2001: Impacts.
Grif¬ths, D. C. (eds.) 1990. Climate Change: The
238 T H E I M PAC T S O F C L I M AT E C H A N G E

67 Global Environmental Outlook 3, p. 272. 75 Details in Hope, C. 2005. Integrated Assessment
68 Stern Review, Chapter 5. Models. In Helm, D. (ed.), Climate-Change Policy.
69 Box 7.4, in Parry et al. (eds.) Climate Change 2007: Oxford: Oxford University Press, pp. 77“98.
Impacts. 76 Stern Review, Chapter 6, pp. 161“2.
70 Dlugolecki, A. 2006. Thoughts about the impact 77 Ibid., Chapter 6, p. 161.
of climate change on insurance claims. In Climate 78 Myers, N., Kent, J. 1995. Environmental Exodus: An
Change and Disaster Workshop, Hohenkammer, Emergent Crisis in the Global Arena. Washington, DC:
Germany, www.eetd.lbl.gov/insurance/ Climate Institute; also Adger, N., Fankhauser, S.
documents/060525.hohenkammer.pdf 1993. Economic analysis of the greenhouse
71 Studies by Cline, Fankhauser, Nordhaus and Tol effect: optimal abatement level and strategies for
presented in Pearce, D. W. et al. 1996. The social mitigation. International Journal of Environment and
costs of climate change. Chapter 6, in Bruce, J., Pollution, 3, 104“19.
Hoesung Lee, Haites, E. (eds.) 1996. Climate Change 79 Adger and Fankhauser 1993.
1995: Economic and Social Dimensions of Climate Change. 80 Cline, W. R. 1992. The Economics of Global Warming.
Cambridge: Cambridge University Press. Washington, DC: Institute for International
72 For equivalent CO2 this is likely to occur around the Economics, Chapter 2.
middle of the twenty-¬rst century; see Chapter 6. 81 Nordhaus, W. D., Boyer, J. 2000. Warming the World:
73 Stern Review, Chapter 6. Economic Models of Global Warming. Cambridge, Mass:
74 Smith, J. B. et al. Vulnerability to climate change MIT Press, pp. 87“91.
and reasons for concern: a synthesis. Chapter 19, 82 See, for instance, Pearce, D. W. et al., in Bruce
Box 19, in McCarthy et al., (eds.) Climate Change et al. (eds.) Climate Change 1995: Economic and Social
2001: Impacts. Dimensions.
Why should we be concerned?

I HAVE been describing the large changes in climate that are beginning to occur as a result of
human activities, and their impact in different parts of the world. But large and devastating
changes are likely to be up to a generation away. So why should we be concerned? What
responsibility, if any, do we have for the planet as a whole and the great variety of other forms of
life that inhabit it, or for future generations of human beings? And does our scienti¬c knowledge
in any way match up with other insights, for instance ethical and religious ones, regarding our
relationship with our environment? In this chapter I want to digress from the detailed consideration
of global warming (to which I shall return) in order brie¬‚y to explore these fundamental questions
and to present something of my personal viewpoint on them.
240 W H Y S H O U L D W E B E CO NC E R N E D?

Earth in the balance
Al Gore, Vice-President of the United States in the Clinton Administration,
entitled his book on the environment Earth in the Balance,1 implying that there
are balances in the environment that need to be maintained. A small area of
a tropical forest possesses an ecosystem that contains some thousands of plant
and animal species, each thriving in its own ecological niche in close balance
with the others. Balances are also important for larger regions and for the Earth
as a whole. These balances can be highly precarious, especially where humans
are concerned.
One of the ¬rst to point this out was Rachel Carson in her book Silent Spring,2
¬rst published in 1962, which described the damaging effects of pesticides on
the environment. Humans are an important part of the global ecosystem; as the
size and scale of human activities continue to escalate, so can the seriousness
of the disturbances caused to the overall balances of nature. Some examples of
this were given in the last chapter.
It is important that we recognise these balances, in particular the careful
relationship between humans and the world around us. It needs to be a bal-
anced and harmonious relationship in which each generation of humans should
leave the Earth in a better state, or at least in as good a state as they found it.
The word that is often used for this is sustainability “ politicians talk of sus-
tainable development, a concept de¬ned in Chapter 9 (box on page 272) and
further analysed in Chapter 12 (page 393). This principle, and its link with the
harmonious relationship between humans and nature, was given prominent
place by the United Nations Conference on Environment and Development held
at Rio de Janeiro in Brazil in June 1992. The ¬rst principle in a list of 27 in the
Rio Declaration adopted by the Conference is ˜Human beings are at the centre
of concerns for sustainable development. They are entitled to a healthy and pro-
ductive life in harmony with nature.™3
However, despite such statements of principle from a body such as the United
Nations, many of the attitudes that we commonly have towards the Earth are
not balanced, harmonious or sustainable. Some of these are brie¬‚y outlined in
the following paragraphs.

Humankind has over many centuries been exploiting the Earth and its resources.
It was at the beginning of the Industrial Revolution some 200 years ago that
the potential of the Earth™s minerals began to be realised. Coal, the result of
the decay of primaeval forests and laid down over many millions of years, was

the main source of energy for the new industrial developments. Iron ore to
make steel was mined in vastly increased quantities. The search for other met-
als such as zinc, copper and lead was intensi¬ed until today many millions of
tonnes are mined each year. Around 1960, oil took over from coal as the domi-
nant world source of energy; oil and gas between them now supply over twice
the energy supplied by coal.
We have not only been exploiting the Earth™s mineral resources. The Earth™s
biological resources have also been attacked. Forests have been cut down on a
large scale to make room for agriculture and for human habitation. Tropical for-
ests are a particularly valuable resource, important for maintaining the climate
of tropical regions. They have also been estimated to contain perhaps half of all
the Earth™s biological species. Yet only about half of the mature tropical forests
that existed a few hundred years ago still stand.4 At the present rate of destruc-
tion virtually all will be gone by the end of the twenty-¬rst century.
Great bene¬ts have come to humankind through the use of fossil fuels,
minerals and other resources. Yet, much of this exploitation has been carried
out with little or no thought as to whether this use of natural resources has been
a responsible one. Early in the Industrial Revolution it seemed that resources
were essentially limitless. Later on, as one source ran out others became avail-
able to more than take its place. Even now, for most minerals new sources are
being found faster than present sources are being used. But the growth of use is
such that this situation cannot continue. In many cases known reserves or even
likely reserves will begin to run out during the next hundred or few hundred
years. These resources have been laid down over many millions if not billions
of years. Nature took about a million years to lay down the amount of fossil
fuel that we now burn worldwide every year “ and in doing so it seems that we
are causing rapid change of the Earth™s climate. Such a level of exploitation is
clearly not in balance, not harmonious and not sustainable.

˜Back to nature™
Almost the reverse of this attitude is the suggestion that we all adopt a much
more primitive lifestyle and give up a large part of industry and intensive farm-
ing “ that we effectively put the clock back two or three hundred years to before
the Industrial Revolution. That sounds very seductive and some individuals can
clearly begin to live that way. But there are two main problems.
The ¬ rst is that it is just not practical. The world population is now some
six times what it was 200 years ago and about three times that of 50 years
ago. The world cannot be adequately fed without farming on a reasonably
intensive scale and without modern methods of food distribution. Further,
242 W H Y S H O U L D W E B E CO NC E R N E D?

most people that have them would not be
prepared to be without the technical aids
“ electricity, central heating, refrigerator,
washing machine, television and so on “
that give the freedom, the interest and the
entertainment that is so much taken for
granted. Moreover, increasing numbers
of people in the developing world are also
taking advantage of and enjoy these aids to
a life of less drudgery and more freedom.
The second problem is that it fails to take
account of human creativity. Human scien-
ti¬c and technical development cannot be
frozen at a given point in history, insisting
that no further ideas can be developed. A
proper balance between humans and the
The golden toad is an amphibian which was indigenous
environment must leave room for humans
to only a 5-km2 region of Costa Rica, and is now believed
to exercise their creative skills.
to be extinct. It is considered by some as one of the ¬rst
Again, therefore, a ˜back to nature™ view-
creatures whose extinction can be de¬nitively blamed
on global warming. These toads only mate during a few point is neither balanced nor sustainable.
weeks in April and May and depend upon seasonal pools
of rainwater in which to lay their eggs. Warming sea sur-
The technical ¬x
face temperatures in the adjacent oceans are blamed for
decreased rainfall and drier conditions in the cloud forest
A third common attitude to the Earth is to
where the golden toad made its home.
invoke the ˜technical ¬ x™. As a senior envi-
ronmental of¬cial from the United States
said to me some years ago, ˜We cannot change our lifestyle because of the pos-
sibility of climate change, we just need to ¬ x the biosphere.™ It was not clear just
what he supposed the technical ¬ xes would turn out to be. The point that he
was making is that, in the past, humans have been so effective at developing
new technology to meet the problems as they arise, can it not be assumed that
this will continue? Concern about the future then turns into ¬nding the ˜¬ xes™
as they are required.
On the surface the ˜technical ¬ x™ route may sound a good way to proceed; it
demands little effort and no foresight. It implies that damage can be corrected
when it has been created rather than avoided in the ¬rst place. But damage
already done to the environment by human activities is causing problems now.
It is as if, in looking after my home, I decided not to carry out any routine main-
tenance but ˜¬ xed™ the failures as they occurred. For my home that would be a
high-risk route to follow: failure to rewire when necessary could easily lead to

a disastrous ¬re. A similar attitude to the Earth is both arrogant and irrespon-
sible. It fails to recognise the vulnerability of nature to the large changes that
human activities are now able to generate.
Science and technology possess enormous potential to assist in caring for the
Earth, but they must be employed in a careful, balanced and responsible way.
The ˜technical ¬ x™ approach is neither balanced nor sustainable.

The unity of the Earth
Having described attitudes that are not balanced or harmonious in their rela-
tionship to the Earth and that fail to contribute to sustainability, I now turn to
describe attitudes that adequately address the problems that I have been pre-
senting in this book, namely the damage to the Earth™s ecosystems destroying
species at an alarming rate and the damage to large numbers of the world™s
peoples especially those who are already poor and disadvantaged. These are
bound to represent the responsibilities that we all have not just for each other
but also for the larger world of all living things. We are, after all, part of that
larger world. There is good scienti¬c justi¬cation for this. We are becoming
increasingly aware of our dependence on the rest of nature and of the interde-
pendencies that exist between different forms of life, between living systems
and the physical and chemical environment that surrounds life on the Earth “
and indeed between ourselves and the rest of the universe.
The scienti¬c theory named Gaia after the Greek Earth goddess and publicised
particularly by James Lovelock emphasises these interdependencies.5 Lovelock
points out that the chemical composition of the Earth™s atmosphere is very dif-
ferent from that of our nearest planetary neighbours, Mars and Venus. Their
atmospheres, apart from some water vapour, are almost pure carbon dioxide.
The Earth™s atmosphere, by contrast, is 78% nitrogen, 21% oxygen and only 0.03%
carbon dioxide. So far as the major constituents are concerned, this composition
has remained substantially unchanged over many millions of years “ a fact that
is very surprising when it is realised that it is a composition that is very far from
chemical equilibrium.
This very different atmosphere on the Earth has come about because of the
emergence of life. Early in the history of life, plants appeared which photosyn-
thesise, taking in carbon dioxide and giving out oxygen. There followed other
living systems that ˜breathe™, taking in oxygen and giving out carbon dioxide.


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