Page 16 - Managing Global Warming

10 Managing Global Warming

1.5 Why we must act now

There is a growing threat of environmental collapse in the future, as a result of changes
in our present climate. We are beginning to see this with extreme weather events such
as flooding, droughts and water crises, high winds, runaway fires, washaways and mud
flows from land denuded of its natural rain soaking properties, high seas in coastal
areas, together with rising sea levels, to mention a few. One consequence of climate
change is the migration of insects and animals to more hospitable climates. A more
frightening involuntary mass migration has already begun: of humans from lands
unable to support the growing of crops and from areas where rising sea levels are
beginning to threaten livelihood. It is not only natural disasters that are a cause for
concern but also man-made disasters, which result indirectly from global warming
that are a cause for concern. These include the reduced ability of land to soak up rain
water as a result of land clearances and urban development resulting in flooding;
chemical pollution in the form of pesticides, endocrine disruptors and hormonally
active agents used on farms to increase yields; nuclear disasters through extreme
weather; land-use decisions for agriculture; oil fires, coal mine fires, and even tire
fires, which add their own contribution to rising CO 2 levels [30].

1.6 What must be done to reduce global warming?

Most world governments have accepted the assessment of the United Nations
Framework Convention on Climate Change (UNFCCC) that a 2°C rise in mean global
temperature above the preindustrial level must be the maximum limit. In order to meet
this objective, studies generally indicate the need for global greenhouse gas emissions
to peak before 2020 with a substantial reduction in emissions thereafter.
We need to reduce the amount of CO 2 entering the atmosphere and if possible we
should find ways of removing some of the CO 2 presently in the atmosphere. Present-
day CO 2 levels in the atmosphere exceed the natural equilibrium of dissolved CO 2
in the oceans and with the CO 2 uptake by biota on land. Unfortunately, this rising
nonequilibrium amount of CO 2 remains in the air for a very long time (see
Table 1.3). The reason is that CO 2 , unlike other greenhouse gases such as CH 4 , is very
unreactive. It does not naturally react with most chemicals and, in thermodynamic
terms, it has a very high Gibbs Energy of Formation. In order to bring about a reaction
of CO 2 with another chemical, a significant amount of energy must be given to the
system (e.g., heat energy). This is also the reason why it is so difficult to get rid of
waste CO 2 from chemical reactions (e.g., cement manufacture, or even from burning
fossil fuels) and why it is rarely used as a chemical feedstock in industry.
There are massive reserves of coal oil and gas in the earth. These convenient
sources of energy are not only easy to use for heating and for producing energy,
but also exist in a stored form, which allows them to be used at any time in the future.
The reserves are summarized in Table 1.4 together with the expected lifetime of usage.
Our future mindset must however not be seduced by the convenient properties of fossil