Geography Reference
In-Depth Information
already running short of water, a function not only of climate change and the over-
utilization of artesian wells, but because nearby rivers are not being replenished. An
even greater effect of the warming is the more rapid melting of ice in polar-regions
which will raise sea-levels, threatening the viability of many low-lying islands, and
having negative effects on coastal cities and communities. These settlements, that
include many of the world's greatest cities, will not simply be at danger from the
new sea levels but will also be more prone to storm surges. This means that more
preventative measures are needed to increase their resilience to these hazards, issues
discussed in the Resilient Cities (Chap. 9). There will also be an increased acidifica-
tion of oceans, for they have absorbed at least a third of our fossil carbon emissions
in recent decades (IPCC
2013
). Although this ocean absorption has reduced the
warming effect on land, the increased acidification of the oceans has accelerated
and is at levels that are the highest for 300 million years according to a recent report
from the International Programme on the State of Ocean (IPSO Oct.
2013
). A major
negative effect of this change will be to gradually dissolve the carbonate skeletons
that form the structure of coral reefs. This will help destroy a major fish habitat, let
alone a tourist resource, within the next few decades. It will add to the existing crisis
in fish stocks and hence food supply, for it is estimated at least 70 % of fish stocks
over currently over-exploited (Roberts
2012
).
Yet the problems associated with climate change are not universal. Cities and
regions may be differentially affected given the local conditions. Indeed three broad
types of global warming effects on urban places can be recognized (IPCC
2014
. TE
2014c
). One category is when the climate change has a major effect, such as rising
sea levels due to polar icecap melting, perhaps 0.2 to 0.4 metres by 2050. Hallegatte
and colleagues (2013) estimated the annual costs of flooding in the largest 136
coastal cities was $5 billion in 2005 and could increase to $1 trillion by 2050, well
above the $62 billion expected then due to growth and subsidence alone. In other
cases the changes may be moderate, so that warming trends may be mitigated by
environmental improvements to city designs, or by anticipating the likelihood of
the poleward spread of malaria-carrying mosquitoes which will, without mitigating
health policies, increase mortality and morbidity rates. These and other possible
consequences are primarily public health and nutrition issues that are more easily
modifiable. In the third case the climate change may be less influential, except in
cases of already marginal environments, being related to such issues as the dif-
ferential ability of various species, including humans, to survive in a location that
becomes hotter or drier. For settlements in these areas there will be need for im-
proved water supplies and better ways of reducing the effect of heat. In terms of
agriculture, which may supply local or regional food needs, the changes mean that
either new varieties will need to be bred, or new land use practices implemented,
with help given to those affected by the transition. More generally it is important
to realize that many different effects can be produced by these warming trends in
various regions and in settlements. This means that many different types of policies
specific to cities and regions to mitigate the effect of the changes will be needed
It is also worth observing that there has been an unexpected pause in the global
warming in the last decade. This has been calculated as being as much as 0.2 ﾰC
