Environmental Engineering Reference
In-Depth Information
in order to avoid significant changes in global climate and the consequent impact on human habitat
and ecological systems.
In 1999 the American Geophysical Union (AGU) issued a position statement on global climate
change, part of which we quote
1
:
...
present understanding of the earth climate system provides a compelling basis for legitimate
public concern over future global- and regional-scale changes resulting from increased concentra-
tions of greenhouse gases. These changes are predicted to include increases in global mean surface
temperatures, increases in global mean rates of precipitation and evaporation, rising sea levels, and
changes in the biosphere
....
The world may already be committed to some degree of human-caused
climate change, and further buildup of greenhouse gas concentrations may be expected to cause
further change. Some of these changes may be beneficial and others damaging for different parts
of the world. However, the rapidity and uneven geographic distribution of these changes could be
very disruptive. AGU recommends the development and evaluation of strategies such as emissions
reduction, carbon sequestration, and the adaptation to the impacts of climate change. AGU believes
that the present level of scientific uncertainty does not justify inaction in the mitigation of human
induced climate change and/or the adaptation to it.
Similarly, in 1995, the Intergovernmental Panel on Climate Change (IPCC) concluded
2
:
Our ability to quantify the human influence on global climate is currently limited because the
expected signal is still emerging from the noise of natural climate variability, and because there
are uncertainties in key factors. These include the magnitude and patterns of long-term natural
variability and the time-evolving pattern of forcing by, and response to, changes in the concentrations
of greenhouse gases and aerosols, and land surface changes. Nevertheless, the balance of evidence
suggests a discernible influence on global climate.
Based on the IPCC recommendations, the Framework Convention on Climate Change con-
vened in Kyoto in late 1997 to discuss international efforts on curbing greenhouse gas emissions.
The developed countries and the so-called “transition countries” (mainly the former USSR and
eastern European countries) agreed that by 2010 they would reduce their CO
2
emissions to an
average of 6-8% below 1990 emission levels. (Because CO
2
emissions in the developed countries
are increasing on average by 1.5-2% per year, the emission reduction target in 2010 would be
much greater than 6-8% below unconstrained 2010 levels.) Unfortunately, the lesser developed
countries, including China, India, Indonesia, Mexico, and Brazil, did not sign the Kyoto agree-
ment. Also, some developed countries, notably the United States, had not ratified the agreement by
2000.
3
Thus, it is doubtful that significant CO
2
and other greenhouse gas emission reductions will
be achieved in the near future, except in countries where there is an economic downturn. (Histori-
cally, economic growth was always associated with increased CO
2
emissions, whereas economic
recession was also associated with decreased emissions.)
In this chapter we explain the characteristics of the greenhouse effect, the predicted trend of
global warming and climate change, and the possible means to ameliorate these effects.
1
EOS, Trans. Am. Geophys. Union,
80,
49, 1999.
2
Houghton, J. T., G. J. Jenkins, and J. J. Ephraums, Eds., 1995.
Climate Change, the IPCC Scientific Assessment
.
Cambridge: Cambridge University Press.
3
In 2001, President George W. Bush declared that the Kyoto agreement is “fatally flawed,” and that the United
States will not abide by its recommendations of greenhouse gas emission reductions.
