Global Warming - Energy and the Environment - page 267

10

CHAPTER

Global Warming

10.1 INTRODUCTION

Of all environmental effects of fossil fuel usage, global warming, including its concomitant cli-
mate change, is the most perplexing, potentially most threatening, and arguably most intractable.
It is caused by the ever-increasing accumulation in the atmosphere of CO 2 and other gases, such
as CH 4 ,N 2 O, chlorofluorocarbons (CFCs), and aerosols, largely due to emissions of these gases
from anthropogenic activities, and reaches levels that exceed those that existed for centuries before
the beginning of the industrial revolution. Called greenhouse gases, these substances augment the
greenhouse effect of the earth's atmosphere, which provides a warmer climate at the earth's sur-
face than would exist in an atmosphere-free earth.
Global warming is an enhancement of the greenhouse effect of the earth's atmosphere, resulting
in an increase of the annual average surface temperature of the earth on the order of 0.5-1 ◦ C since
the middle of the nineteenth century. While yet small, this temperature rise might reach 2-3 ◦ C
by the end of the twenty-first century, an amount believed almost certain to cause global climate
changes affecting all biological life on the planet with uncertain consequences.
Most of the emissions of greenhouse gases and aerosols are a consequence of fossil fuel usage
to satisfy our growing energy needs. The burning of 1 kg of coal liberates about 3.4 kg of CO 2 ; that
of oil, 3.1 kg; and that of natural gas, 2.75 kg. In 1996, the global anthropogenic emissions of CO 2
amounted to over 25 gigatons per year (Gty − 1 ). Methane emissions are in part due to fossil energy
usage, as CH 4 leaks from gas pipes, storage tanks, tankers, and coal mine shafts. In 1996, the global
anthropogenic emissions of CH 4 amounted to 0.4 Gty − 1 . Nitrous oxide (N 2 O) is a minor product
of combustion of fossil fuels. CFCs are not directly associated with fossil fuel usage; however,
they are emitted inadvertently from energy-using devices, such as refrigerators, air conditioners,
chillers, and heat pumps.
The prevention of global warming will require a very significant shift from our present en-
ergy use pattern toward one of lesser reliance on fossil fuels. Inevitably, such a shift will cause a
higher cost for energy commodities, employment disruptions (not necessarily job losses, but differ-
ent employment patterns), development of alternative technologies, efficiency improvements, and
conservation measures. Because of the expected socioeconomic disruptions, there is considerable
opposition to implementing preventative policies. Opposition comes from affected interest groups,
including coal, oil, and gas suppliers; automobile manufacturers; steel, cement, and other heavy
industries; their financiers and shareholders; and their political representatives. Opposition comes
also from developing countries, which claim that their peoples' economic standard is so much
lower compared to that in more developed countries that increased use of fossil fuel is necessary to
elevate their standard. On the other hand, most scientists consider preventative measures a necessity

267