176 The impactsof climate change
threatened ecosystems are those that could mitigate against some climate
change impacts (e.g. coastal systems that buffer the impact of storms).
Possible adaptation methods to reduce the loss of biodiversity include
the establishment of refuges, parks and reserves with corridors to allow
migration of species, and the use of captive breeding and translocation
of species.^52
So far we have been considering ecosystems on land. What about
those in the oceans; how will they be affected by climate change? Al-
though we know much less about ocean ecosystems, there is considerable
evidence that biological activity in the oceans has varied during the cycle
of ice ages. Chapter 3 noted (see box on page 35) the likelihood that it
was these variations in marine biological activity which provided the
main control on atmospheric carbondioxide concentrations during the
past million years (see Figure 4.4). The changes in ocean water tempera-
ture and the possible changes in some of the patterns of ocean circulation
are likely to result in changes in the regions where upwelling occurs and
where fish congregate. Some fisheries could collapse and others expand.
At the moment the fishing industry is not well adapted to address major
change.^53
Some of the most important marine ecosystems are found within
coral reefs that occur in many locations throughout the tropical and
subtropical world. They are especially rich in biodiversity and are par-
ticularly threatened by global warming. Within them the species diver-
sity contains more phyla than rainforests and they harbour more than
twenty-five per cent of all known marine fish.^54 They represent a signif-
icant source of food for many coastal communities. Corals are partic-
ularly sensitive to sea surface temperature and even one degree Celsius
of persistent warming can cause bleaching (paling in colour) and ex-
tensive mortality accompanies persistent temperature anomalies of 3◦C
or more. Much recent bleaching, for instance that in 1998, have been
associated with El Ni ̃no events.^55The impact on human health
Human health is dependent on a good environment. Many of the factors
that lead to a deteriorated environment also lead to poor health. Pollution
of the atmosphere, polluted or inadequate water supplies, and poor soil
(leading to poor crops and inadequate nutrition) all present dangers to
human health and wellbeing and assist the spread of disease. As has
been seen so far in considering the impacts of global warming, many
of these factors will tend to be exacerbated through the climate change
that will occur in the warmer world. The greater likelihood of extremes
of climate, such as droughts and floods, will also bring greater risks to