Background to Sustainable Cities - Theme Cities: Solutions for Urban Problems - page 198

mimic the effect of major volcanic eruptions which add large amounts of dust into
the upper atmosphere and which travel around the world. Historically this has led
to lower temperatures and poor harvests even on other continents far from the erup-
tion. But reflecting sunlight only works in the day, so this could lead to cooler days
but warmer nights since the greenhouse gases are still present. A simpler idea is
to 'fertilize' the oceans with iron or other nutrients which will increase the num-
ber of carbon-absorbing plankton that would later sink to the ocean floor, although
this may cause other problems (Shephard et al 2007 ). However these and other
geo-engineering solutions are likely to lead to large regional variations in weather
patterns. So far there is no known way of ensuring the effects will be restricted to
specific areas that might benefit. Their application could cause all sorts of political
disputes if one country applied the technology despite opposition from neighbour-
ing states that may suffer unknown consequences. Of course supporters of the idea
maintain that it is important to experiment with these techniques, even on a small
scale to see what works and to avoid negative effects (Keith 2013 ). To proponents
these approaches are especially important to decrease inequalities since increased
global warming will have its greatest effects on the poorest, not only because of
poorer harvests in marginal areas. More droughts will occur if climate warming
continues, but will also lessen their ability to use the more expensive energy. But
despite passionate advocates (Keith ( 2013 ), the ethical arguments against these geo-
engineering experiments do appear to be stronger, because there is no guarantee that
unforeseen negative side effects will occur. It is worth remembering that fossil fuels
seemed to be the solution to man's need for portable energy, with their pollution
effects being ignored. But in the last 20 years their side-effects are proving to be of
planet-threatening significance. So most people today believe that we cannot take
the chance of using geo-engineering given our current knowledge, and especially
because of the difficulty of spatial targeting and side-effect problems. This led the
2010 international Convention on Biological Diversity (CBD) in Nagoya (Japan)
to propose a moratorium on geo-engineering to take effect 2 years later “ until there
is an adequate scientific basis on which to justify such activities and appropriate
consideration of the associated risks ” (quoted in Tollefson 2010 , p. 14).

5﻽9 Conclusions

It is only in the last generation that serious attention has been paid to the problems
caused by the negative externalities of our economic development and to the reck-
less over-use of our finite resources. The development of the sustainable movement
has focused attention on these problems and gained world-wide attention. However
the term 'sustainable' is not an easy one to define, as has been shown by a compari-
son of some of the major attempts to summarize its nature. By inter-relating these
definitions a more comprehensive understanding of its multi-dimensional nature
has been revealed, showing that it now encompasses human dimensions as well
as the physical features that dominated its discussion in its early years. A related