Environmental Engineering Reference
In-Depth Information
lated hydrocarbons have either leveled or decreased. The Montreal Protocol has been called the most
successful international environmental agreement in history.
Global Warming and Climate Change
The terms
global warming
and
climate change
often are used interchangeably, but they have different mean-
ings.
Global warming
is the steady increase in the average temperature of the Earth's surface that may be
caused by man-made greenhouse emissions, which lead to increased infrared and thermal radiation near the
Earth's surface. Global warming has been observed since the 1980s and continues to be at the forefront of in-
ternational environmental research and debate. This debate is generally centered on whether the steady temper-
ature increase of the Earth's surface is a natural occurrence or whether it has been accelerated as a result of hu-
man activity.
Climate change
is any change in the state of the climate (for example, temperature) that persists
steadily for many years—decades or longer. Global climate change is a natural process and is best illustrated
by the five known ice ages. Questions about global climate change and the contributions of human activities
will continue to be discussed and evaluated, but regardless of its origins, the Earth is warming.
Global warming is widely associated with an increased concentration of
greenhouse gases
that soak up in-
frared radiation and trap heat in the atmosphere. However, a
natural greenhouse effect
is necessary to keep
the Earth's climate warm and habitable. When the Earth's atmosphere traps solar radiation, it heats up, distrib-
uting this heat to the Earth. Without our atmosphere, the Earth would be uninhabitably hot during the day and
uninhabitably cold at night. Thus, the atmosphere is much like an insulting blanket that traps the heat to keep
the planet at a relatively constant temperature. About 80 percent to 90 percent of the Earth's natural greenhouse
effect is due to water vapor in the atmosphere, which is a greenhouse gas.
