Background Stories

The Basics of Global Warming



Global warming is the term used to describe a gradual increase in the average temperature of the Earth's atmosphere and its oceans, a change that is believed to be permanently changing the Earth’s climate forever.
While many view the effects of global warming to be more substantial and more rapidly occurring than others do, the scientific consensus on climatic changes related to global warming is that the average temperature of the Earth has risen between 0.4 and 0.8 °C over the past 100 years. The increased volumes of carbon dioxide and other greenhouse gases released by the burning of fossil fuels, land clearing, agriculture, and other human activities, are believed to be the primary sources of the global warming that has occurred over the past 50 years.

Causes of Global Warming

-Carbon Dioxide from Power Plants
In 2002 about 40% of U.S. carbon dioxide emissions stem from the burning of fossil fuels for the purpose of electricity generation. Coal accounts for 93 percent of the emissions from the electric utility industry

-Carbon Dioxide Emitted from Cars
About 33% of U.S carbon dioxide emissions comes from the burning of gasoline in internal-combustion engines of cars and light trucks (minivans, sport utility vehicles, pick-up trucks, and jeeps).

-Carbon Dioxide from Airplanes
The UN's Intergovernmental Panel on Climate Change estimates that aviation causes 3.5 percent of global warming, and that the figure could rise to 15 percent by 2050.

-Carbon Dioxide from Buildings
Buildings structure account for about 12% of carbon dioxide emissions.

-Methane
While carbon dioxide is the principal greenhouse gas, methane is second most important. According to the IPCC, Methane is more than 20 times aseffective as CO2 at trapping heat in the atmosphere.

-Nitrous oxide
Another greenhouse gas is Nitrous oxide (N2O), a colourless, non-flammable gas with a sweetish odour, commonly known as "laughing gas", and sometimes used as an anaesthetic. Nitrous oxide is naturally produced by oceans and rainforests. Man-made sources of nitrous oxide include nylon and nitric acid production, the use of fertilisers in agriculture, cars with catalytic converters and the burning of organic matter. Nitrous oxide is broken down in the atmosphere by chemical reactions that involve sunlight.

-Deforestation
After carbon emissions caused by humans, deforestation is the second principle cause of atmospheric carbn dioxide. (NASA Web Site) Deforestation is responsible for 20-25% of all carbon emissions entering the atmosphere, by the burning and cutting of about 34 million acres of trees each year.

-City Gridlock
In 1996 according to an annual study by traffic engineers [as reported in the San Francisco Chronicle December 10, 1996] from Texas A and M University, it was found that drivers in Los Angeles and New York City alone wasted 600 million gallons of gas annually while just sitting in traffic. The 600 million gallons of gas translates to about 7.5 million tons of carbon dioxide in just those two cities.


Effects of Global Warming

And the effects of rising temperatures aren’t waiting for some far-flung future. They’re happening right now. Signs are appearing all over, and some of them are surprising. The heat is not only melting glaciers and sea ice, it’s also shifting precipitation patterns and setting animals on the move.
Some impacts from increasing temperatures are already happening.


i-Ice is melting worldwide, especially at the Earth’s poles. This includes mountain glaciers, ice sheets covering West Antarctica and Greenland, and Arctic sea ice.


ii-Researcher Bill Fraser has tracked the decline of the Adélie penguins on Antarctica, where their numbers have fallen from 32,000 breeding pairs to 11,000 in 30 years.


iii-Sea level rise became faster over the last century.


iv-Some butterflies, foxes, and alpine plants have moved farther north or to higher, cooler areas.
v-Precipitation (rain and snowfall) has increased across the globe, on average.


vi-Spruce bark beetles have boomed in Alaska thanks to 20 years of warm summers. The insects have chewed up 4 million acres of spruce trees.


Other effects could happen later this century, if warming continues.


i-Sea levels are expected to rise between 7 and 23 inches (18 and 59 centimeters) by the end of the century, and continued melting at the poles could add between 4 and 8 inches (10 to 20 centimeters).


ii-Hurricanes and other storms are likely to become stronger.
Species that depend on one another may become out of sync. For example, plants could bloom earlier than their pollinating insects become active.


iii-Floods and droughts will become more common. Rainfall in Ethiopia, where droughts are already common, could decline by 10 percent over the next 50 years.


iv-Less fresh water will be available. If the Quelccaya ice cap in Peru continues to melt at its current rate, it will be gone by 2100, leaving thousands of people who rely on it for drinking water and electricity without a source of either.


v-Some diseases will spread, such as malaria carried by mosquitoes.


vi-Ecosystems will change—some species will move farther north or become more successful; others won’t be able to move and could become extinct. Wildlife research scientist Martyn Obbard has found that since the mid-1980s, with less ice on which to live and fish for food, polar bears have gotten considerably skinnier. Polar bear biologist Ian Stirling has found a similar pattern in Hudson Bay. He fears that if sea ice disappears, the polar bears will as well.
Source for climate information: IPCC, 2007Expand/Collapse This