Geography Reference
In-Depth Information
700,000 people in more than 250 communities had been threatened by wildfires, al-
though with few deaths. Such examples of the size of the impact of natural hazards
can be duplicated in many other countries.
More significant than past trends is the fact that these climate and hydrological
natural hazards are likely to continue to increase for the foreseeable future, largely
due to the global warming which increases average temperatures and hence moisture
content and pressure differentials. This gives greater power to storms and leads to
more fire hazards because of increasing temperatures in grasslands and forests. As
previous chapters showed, most scientists believe that the current global warming is
heavily influenced by the build-up of carbon dioxide and other greenhouse or warm-
ing gases in the atmosphere, due to human activity. Certainly the complex nature of
the causes of climate variations still leads a minority to doubt that human activity is
the primary cause, although the numbers of such sceptics among physical scientists
is steadily decreasing. So the progress of global warming is now widely accepted and
will increase the number of floods, storm surges, melting glaciers and permafrost. To
take one example a report prepared for the Asia Development Bank (ADB) estimated
that climate-related disasters accounted for over 70 % of the frequency of the most
intense natural hazard tragedies in Asia from 1971 to 2010, where the large popula-
tions and coastal or river locations of cities make them vulnerable (Thomas et al.
2013 ). Of course individual climate events cannot be attributed to global warming,
but the trends can be. In this respect the ADB report shows the Philippines in particu-
lar is experiencing a greater frequency of large storms, which shows the importance
of recognizing regional variations within the general trends. Among the other conse-
quences, crop production is likely to suffer on balance, through increased droughts
in some areas, which is likely to cause problems in providing adequate food supplies
for some cities. Although there may be some regions where the warming increases
productivity, there will be more losers if a global accounting of the crop-productivi-
ty-global warming association is used. For example, recent forecasts suggest a 20 %
drop in the productivity of spring wheat by 2050 in the developed world if current
trends in greenhouse gas accumulation continue (Arnell et al. 2013 ). It has also been
predicted that Bangladesh, located mainly in the low-lying delta of major rivers, is
especially at risk (Danda & Sriskanthan 2011 ) and, will lose at least a third of its rice
crop and a tenth of its rice yields by mid-century (Oxfam 2008). The general trend
therefore is one of decreasing agricultural yields in a situation of increasing world
population. This will lead to food shortages and famine in many areas, especially
urban areas, unless remedial action, or some new agricultural revolution occurs, such
as from genetically modified crops more able to produce greater yields and being
more resistant to diseases. Yet such changes are opposed by those who see too much
of a farming concentration on a limited number of crop varieties, which reduces the
gene pool and increases vulnerability to disease, as well as worries about the increas-
ing global dominance of a small number of multi-national suppliers of seed.
However much the evidence of disasters from natural hazards hits the headlines,
one of the greatest threats to human life comes from an indirect effect of human
activity, namely pollution, not only from manufactured or waste products, but from
the burning of fossil fuels in all forms. Indeed, the annual report on the Global Bur-
den of Disease (WHO 2013 ) showed air pollution in the top ten of killer diseases
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