Environmental Engineering Reference
In-Depth Information
the overall cost to Germany alone for climate change will amount to around 3000
billion euros by the year 2100 (Kemfert, 2007) if global warming brings about a
4.5 ° C rise in temperature.
2.2 The Guilty Parties - Causes of Climate Change
2.2.1 The Greenhouse Effect
Without the protective infl uence of the atmosphere, earth's temperature would be
around
18 °C. This means we would be living on an ice-bound planet. Various
natural trace gases in the atmosphere - such as steam, carbon dioxide and ozone
- prevent the earth from emitting all incoming solar energy back into the universe.
As in a greenhouse, these gases radiate part of this energy back to earth. This natural
greenhouse effect is the basis for life on earth. As a result, the average temperature
has settled at around +15 °C. During the last few millennia a balance has been
created in the level of trace gases in the atmosphere, which has enabled life in the
form that we know it today.
Many different possible causes of observed climate change have already been dis-
cussed. For a long time sceptics even questioned whether climate change was really
taking place. Now that no one can really seriously claim that it is not getting warmer,
there are some who are trying to push the blame onto natural effects - for example,
on solar activity. Apparently solar activity during the last few decades has been
higher than in all the previous 8000 years. It has been demonstrated that the amount
of radiation that reaches the earth has indeed risen slightly. However, scientists rule
out the possibility that this is what is causing the high level of warming today. At
most, one-tenth of the observed increase in temperature is attributed to the rise in
solar activity (Figure 2.5 ).
−
Figure 2.5
Changes in solar activity
are responsible for only a fraction of
global warming.
Picture: NASA.
