Curtesy: www.nrdc.org
What Causes Climate Change?
The mechanics of the earth’s climate system are simple. When energy from the sun is reflected off the earth and back into space (mostly by clouds and ice), or when the earth’s atmosphere releases energy, the planet cools. When the earth absorbs the sun’s energy, or when atmospheric gases prevent heat released by the earth from radiating into space (the greenhouse effect), the planet warms. A variety of factors, both natural and human, can influence the earth’s climate system.
Natural causes of climate change
The earth has gone through warming and cooling phases in the past, long before humans were around. Forces that can contribute to climate change include the sun’s intensity, volcanic eruptions, and changes in naturally occurring greenhouse gas concentrations. But records indicate that today’s climatic warming—particularly that which has occurred since the mid-20th century—is happening at a much faster rate than ever before, and it can’t be explained by natural causes alone. According to NASA, “[t]hese natural causes are still in play today, but their influence is too small or they occur too slowly to explain the rapid warming seen in recent decades.”
Anthropogenic causes of climate change
Humans—more specifically, the greenhouse gas (GHG) emissions that human activity generates—are the leading cause of the earth’s rapidly changing climate today. Greenhouse gases play an important role in keeping the planet warm enough to inhabit. But the amount of these gases in our atmosphere has skyrocketed in recent decades. According to the U.S. Environmental Protection Agency, our current concentrations of carbon dioxide, methane, and nitrous oxide “are unprecedented compared with the past 800,000 years.” Indeed, the atmosphere’s share of carbon dioxide—the planet’s chief climate change contributor—has risen by 46 percent since preindustrial times.
