190 The impactsof climate change
costing can only represent a part of the overall impact story. Any
assessment of impacts has to take into account the cost in human
terms and the large social and political disruption some of the impacts
will bring. In particular, it is estimated that there could be up to three
million new environmental refugees each year or over 150 million by
the middle of the twenty-first century.It is important to bear in mind that these estimates of overall impact have
concentrated on the doubled carbon dioxide scenario (in other words, the
next fifty or sixty years). Soon after the end of the twenty-first century,
under the scenarios with higher carbon dioxide emissions (in other words,
if strong action is not taken to curb emissions), a further doubling of the
equivalent carbondioxide concentration will have occurred and it will be
continuing to rise. The impacts of the additional climate change which
would occur with a second effective doubling of carbon dioxide will be
substantially more severe than those of the first doubling.
That, of course, is a lot further away in time; perhaps for that reason it
has not been given much attention. However, because of the long life-time
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. The much more severe impacts that can be expected at longer
time horizons(see Table 7.4) increase the imperative now to take the
necessary action.
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.Questions
1 For your local region, find 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 thenext fifty 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, find out about current environmental problems such
as sea level rise due to subsidence, over-use of ground water, 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 one hundred 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
adaptation reduce each type of damage?