July 28, 2012
“Global warming is the observed and projected increases in the average temperature of Earth's atmosphere and oceans. The Earth's average temperature rose about 0.6° Celsius (1.1° Fahrenheit) in the 20th century (Jurg, 2009).”
“Global warming has become perhaps the most complicated issue facing world leaders today. With many warnings from the scientific community becoming louder, due to an increasing body of science pointing to rising dangers from the ongoing buildup of human-related greenhouse gases — produced mainly by the burning of fossil fuels and forests (Revkin, 2012).”
To figure out what is causing global warming, Scientists have spent decades trying to figure this out. They have looked at the natural cycles and events that are known to influence climate. But the amount and pattern of warming that's been measured can't be explained by these factors alone. The only way to explain the pattern is to include the effect of greenhouse gases (GHGs) emitted by humans.
To bring all this information together, the United Nations formed a group of scientists called the Intergovernmental Panel on Climate Change, or IPCC. The IPCC meets every few years to review the latest scientific findings and write a report summarizing all that is known about global warming. Each report represents a consensus, or agreement, among hundreds of leading scientists (National Geographic, 2012).
Scientists have learned that there are several greenhouse gases responsible for warming, and humans emit them in a variety of ways. Most of these greenhouse gases come from the combustion of fossil fuels in cars, factories and electricity production. “The gas responsible for the most warming is carbon dioxide, also called CO2. Other contributors include methane released from landfills and agriculture (especially from the digestive systems of grazing animals), nitrous oxide from fertilizers, gases used for refrigeration and industrial processes, and the loss of forests that would otherwise store CO2 (National Geographic, 2012).”
Global emissions of carbon dioxide jumped by the largest amount on record in 2010, rising 5.9 percent, according to the Global Carbon Project, an international collaboration of scientists. This increase solidified a trend of ever-rising emissions that scientists fear will make it difficult, if not impossible, to predict severe climate change in coming decades (Revkin, 2012).
Our planet is on a warming trend, from North Pole to South Pole, and everywhere in between. Globally, the mercury is already up more than 1 degree Fahrenheit (0.8 degree Celsius), and even more in sensitive Polar Regions. The heat is not only melting glaciers and sea ice; it’s also shifting precipitation patterns and setting animals on the move.
Some impacts already seen from increasing temperatures:
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.
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.
Sea level rise became faster over the last century.
Some butterflies, foxes, and alpine plants have moved farther north or to higher, cooler areas.
Precipitation (rain and snowfall) has increased across the globe, on average.
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.
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).
Hurricanes and other storms are likely to become stronger.
Species that depend on one another may become out of sync. For example,