The Secrets In Ice Cores
by Daniel Grossman

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Rivulets of rainwater run off the roofs of a tidy neighborhood in the suburbs of Boston. The water flows down the driveways and across the street and disappears into a storm drain. From there it's flushed into the Atlantic Ocean. This rainwater, combined with water from melting glaciers far north of here, may be diluting the Atlantic, making it less salty, or fresher. It seems far-fetched, but some scientists say the foundation of civilization itself could by influenced by these drops.

And scientists say all of us are responsible. It has to do with global warming, caused by the carbon dioxide produced when fossil fuels like oil or coal are burned, for instance, to make electricity. NASA climate expert James Hansen says Americans produce more of this gas than the people of any other country. And it's piling up.

"Carbon dioxide," says Hansen, "has increased from about 280 parts per million that existed 150 years ago to about 370 right now." That's a thirty percent increase.

One way to see how that gas and several others are warming things up is to hop into a car on a sunny day.

Inside the car, it's hot. Why? Because sunlight is pouring in the windows and is beating down on the dark seats. These hot surfaces slowly release the energy they absorb, heating the air. But the heat can't escape through the windows, which act like an insulating blanket. The greenhouse effect works much the same way. Gasses like carbon dioxide in the atmosphere are like the car's windows, letting sunlight come in, but keeping heat from going out to space. In moderation, this insulation is good. It helps make Earth warm enough for life. The problem is, humans are creating more and more insulation by using fuels like the gasoline in our cars. Scientist James Hansen compares the warming caused by humans to the amount of heat produced by the tiny bulbs hung on Christmas trees.

"So it's equivalent to having two of the tiny Christmas tree bulbs over each square meter of the Earth's surface."

Multiply that by the Earth's huge surface area, 550 trillion square meters, and what you'd get would be equal to the amount of energy produced by about one million of the largest nuclear power plants. And ever so slowly, that has heated the planet.

"Temperature on the average is indeed rising," says Hansen. "It's increased about 3/4 of a degree Celsius, which is more than one degree Fahrenheit over the last century."

One degree Fahrenheit might not sound like much because we're used to daily temperature changes of ten or more degrees between when we get up in the morning and lunch, but Hansen says, averaged over the entire globe, one degree is significant. Hansen shook up the world one hot summer day in 1988 when he told a congressional committee that humans were warming the Earth. His was a minority opinion then, but it's scientific consensus now. And over the years, evidence has accumulated that this warming is having an impact.

The most obvious changes are taking place at the Earth's poles, which have warmed the most. For instance, winter temperatures on the Antarctic Peninsula have climbed an alarming 10 degrees Fahrenheit in the last 50 years, and the ice cap over the Arctic Ocean has lost 40 percent of its volume the last 30 years. One researcher says this warming will cause Adelie Penguins to disappear from that part of the southern continent within a decade.

Next - Polar Expeditions Reveal Dramatic Change

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