GLOBAL WARMING
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For 2.5 million years, the earth’s climate has fluctuated
cycling from ice ages to warmer periods
But in the last century, the planet’s temperature has risen unusually fast
about 1.2 to 1.4 degrees Fahrenheit
Scientists believe it’s human activity that’s driving the temperatures up
a process known as global warming
Ever since the industrial revolution began
factories, power plants, and eventually, cars
have burned fossil fuels such as oil and coal
releasing huge amounts of carbon dioxide and other gases into the atmosphere
These greenhouse gases trap heat near the earth through a naturally occurring process called the greenhouse effect
The greenhouse effect begins with the sun and the energy it radiates to the earth
The earth and the atmosphere absorb some of this energy
while the rest is radiated back into space
Naturally occurring gases in the atmosphere trap some of this energy and reflect it back
warming the earth
Scientists now believe that the greenhouse effect is being intensified by the extra greenhouse gases that humans have released
Evidence for global warming includes a recent string of very warm years
Scientists report that 1998 was the warmest year in measured history, with 2005 coming in second
Meanwhile, readings taken from ice cores show that the greenhouse gases, carbon dioxide and methane have hit their highest levels in the past 420,000 years
Arctic sea ice is also shrinking
According to NASA studies, the extent of Arctic sea ice has declined about 10% in the last 30 years
As long as industrialized nations consume energy
and developing countries increase their fossil fuel consumption
the concentration of greenhouse gases in the atmosphere will continue to rise
Researchers predict that temperatures will increase about 2 to10 degrees Fahrenheit by the end of the century.
What’s less certain is what rising temperatures mean for the planet.
Some climate models predict subtle changes
Others forecast rising sea levels which could flood coastal areas around the world
Weather patterns could change, making hurricanes more frequent
Severe droughts could become more common in warm areas
and species unable to adapt to the changing conditions would face extinction
Although much remains to be learned about global warming
many organizations advocate cutting greenhouse gas emissions to reduce the impact of global warming
Consumers can help. By saving energy around the house
switching to compact fluorescent light bulbs
and driving fewer miles in the car each week
These simple changes may help keep the Earth cooler in the future