Page 21 - Solar Power in Building Design The Engineer's Complete Design Resource

INTRODUCTION xix

Global Warming and Climate Change

Ever since the industrial revolution, human activities have constantly changed the nat-
ural composition of Earth’s atmosphere. Concentrations of trace atmospheric gases,
nowadays termed “greenhouse gases,” are increasing at an alarming rate. There is con-
clusive evidence that the consumption of fossil fuels, conversion of forests to agricul-
tural land, and the emission of industrial chemicals are principal contributing factors
to air pollution.
According to the National Academy of Sciences, Earth’s surface temperature has
risen by about one degree Fahrenheit (ºF)in the past century, with accelerated warm-
ing occurring in the past three decades. According to statistical review of the atmos-
pheric and climatic records, there is substantial evidence that global warming over the
past 50 years is directly attributable to human activities.
Under normal atmospheric conditions, energy from the sun controls Earth’s weather
and climate patterns. Heating of Earth’s surface resulting from the sun radiates energy
back into space. Atmospheric greenhouse gases, including carbon dioxide (CO ),
2
methane (CH ), nitrous oxide (N O), tropospheric ozone (O ), and water vapor (H O)
2
3
2
4
trap some of this outgoing energy, retaining it in the form of heat, somewhat like a
glass dome. This is referred to as the greenhouse effect.
Without the greenhouse effect, surface temperatures on Earth would be roughly
30ºC [54 degrees Fahrenheit (ºF)] colder than they are today—too cold to support life.
Reducing greenhouse gas emissions depends on reducing the amount of fossil
fuel–fired energy that we produce and consume.
Fossil fuels include coal, petroleum, and natural gas, all of which are used to fuel
electric power generation and transportation. Substantial increases in the use of non-
renewable fuels is a principal factor in the rapid increase in global greenhouse gas
emissions. The use of renewable fuels can be extended to power industrial, commer-
cial, residential, and transportation applications to substantially reduce air pollution.
Examples of zero-emission, renewable fuels include solar, wind, geothermal,
and renewably powered fuel cells. These fuel types, in combination with advances
in energy-efficient equipment design and sophisticated energy management tech-
niques, can reduce the risk of climate change and the resulting harmful effects on
the ecology. Keep in mind that natural greenhouse gases are a necessary part of sus-
taining life on Earth. It is the anthropogenic or human-caused increase in greenhouse
gases that is of concern to the international scientific community and governments
around the world.
Since the beginning of the modern industrial revolution, atmospheric concentrations
of carbon dioxide have increased by nearly 30 percent, methane concentrations have
more than doubled, and nitrous oxide concentrations have also risen by about 15 percent.
These increases in greenhouse gas emissions have enhanced the heat-trapping capa-
bility of Earth’s atmosphere.
Fossil fuels burned to operate electric power plants, run cars and trucks, and heat
homes and businesses are responsible for about 98 percent of U.S. carbon dioxide
emissions, 24 percent of U.S. methane emissions, and 18 percent of U.S. nitrous oxide