What is the greenhouse effect?

The greenhouse effect is a natural process of the atmosphere that traps some of the Sun's heat near the Earth. The problem with the greenhouse effect, however, is that it has been unnaturally increased, causing more heat to be trapped and the temperature on the planet to rise. The gases that have caused the greenhouse effect were added to the atmosphere as a byproduct of human activities, such as combustion from automobiles.

Who first formed the theory about the greenhouse effect?

Irish physicist, mathematician, and chemist John Tyndall (1820-1893), who succeeded Michael Faraday (1791-1867) as the superintendent of Britain's Royal Institution, began conducting research in radiant heat in 1859. He soon con

A scientist compares ultraviolet wavelengths at a Mauna Loa, Hawaii, research station using an ozone spectrophotometer. (photo by John Bortniak, NOAA Corps)

A scientist compares ultraviolet wavelengths at a Mauna Loa, Hawaii, research station using an ozone spectrophotometer. (photo by John Bortniak, NOAA Corps)

cluded that water vapor was vital for holding in warmth in the Earth's atmosphere, and that other gases, such as carbon dioxide and ozone, also played a role. He proceeded to play with a number of calculations, changing the amounts of these gases in his formulas to discover what the results would be. Tyndall concluded that increasing a gas like carbon dioxide would have significant effects on the climate that we now call global warming.

Is the greenhouse effect a good thing for life on Earth, or bad for the environment?

Like so many things about life on Earth, moderation is the key. Some greenhouse effect is a very good thing for life on Earth. Without any such effect on Earth, the oceans would eventually freeze. If the greenhouse effect increases significantly, however, many living organisms and species, as well as environmental systems that have developed over a long time—including human civilization—will face substantial challenges, and possibly even extinction. In the most extreme case, a runaway greenhouse effect like that on the planet Venus, would cause all life on Earth as we know it to cease to exist. On the other hand, many plants will benefit from increases in carbon dioxide levels, warmer temperatures, and longer growing seasons.

What is global warming?

Global warming and the greenhouse effect are not necessarily the same thing. While the greenhouse effect can cause global warming, other things can lead to the planet warming or cooling. Other factors include changes in geography (plate tectonics) and cycles of the Earth's orbit around the Sun.

It is known that global warming is necessary to a certain point: Without the ability of certain gases in the Earth's atmosphere to help retain radiation from the Sun, our planet would be a cold ice ball in space. These gases act like the glass of a greenhouse (thus the name greenhouse gases), trapping much of the energy emitted from or bounced off the ground and keeping our world warm. This, in turn, allows organisms—plants, animals, and otherwise—to live.

More recently, global warming has been used to describe the unnatural increase in the average surface temperatures around the world. Many scientists (and others) believe humans have pumped excess amounts of greenhouse gases, such as carbon dioxide, methane, and nitrogen oxides, into the atmosphere, causing temperatures to rise. Something has already raised the surface temperatures about 0.5°C (1°F) in the past 100 years, and scientists believe it to be human-induced.

What is the global average temperature?

Data on temperatures for the twentieth century, which includes both land and ocean surface temperatures, averaged to 53.6°F (12°C). A 2007 assessment showed that, during the early years of the twenty-first century, average temperatures were already up 1.28°F (0.71°C) compared to the previous century averages. This data includes a very warm year in 2002 (though 1998 was actually the warmest year since 1990) , and the fact that, taken by themselves, land-surface temperatures have been particularly warmer: 3.4°F (1.89°C). Ocean surface temperatures in 2007 were the fourth warmest in a record database spanning 128 years.

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