Write the short note of global warming and ozone layer
Answers
Explanation:
Global Warming
Global warming and ozone layer depletion are two different problems (see the sidebar “Misconceptions about Global Atmospheric Change” on page 95). Global warming is caused by the “greenhouse effect,” which is essential to life as we know it on planet Earth. Electromagnetic energy coming from the sun is absorbed by the Earth, which radiates some of this energy outward as infrared energy (heat). Some of this infrared energy escapes into space, but much of it is absorbed by “greenhouse gases” in the lower atmosphere (the troposphere) and is radiated back to the Earth as heat energy.
The greenhouse effect, then, is a warming of the Earth’s surface that makes it hospitable to life. Without the greenhouse effect, the surface of the Earth would be a frigid -100°F. Alternatively, a “runaway” greenhouse effect, like that found on the planet Venus, would result in a surface temperature of 900°F or more. Greenhouse gases, including water vapor (H2O), carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), are produced as part of the natural system (for example, CO2 and H2O are by-products of respiration and combustion). These gases act much like the glass roof of a greenhouse, letting sunlight through, but keeping heat locked in.
Since the Industrial Revolution, humans have developed technologies (for example, motor vehicles) that produce large quantities of greenhouse gases. Also, humans have invented new molecules that are greenhouse gases, for example, chlorofluorocarbons (CFCs) and some CFC-substitutes that are used as coolants and solvents. Increased amounts of all types of man-made greenhouse gases released into the atmosphere “enhance” the greenhouse effect. The gas that is most responsible for enhancing the greenhouse effect is CO2, because human activities create so much of it and it has a long “lifetime” in the atmosphere (meaning that molecules are present in the air for a long time before being used by plants . and ozone layer
An ozone molecule (O3) is composed of three atoms of oxygen. Ozone in the upper atmosphere (the stratosphere) is referred to as the “ozone layer” and protects life on Earth by absorbing most of the ultraviolet (UV) radiation emitted by the sun. Exposure to too much UV radiation is linked to skin cancer, cataracts, and depression of the immune system, and may reduce the productivity of certain crops. Accordingly, stratospheric ozone is known as “good ozone.” In contrast, human industry creates “ozone pollution” at the ground level. This “bad ozone” is a principal component of smog. The ozone layer is reduced when man-made CFC molecules (comprised of chlorine, fluorine, and carbon) reach the stratosphere and are broken apart by short-wave energy from the sun. Free chlorine atoms then break apart molecules of ozone, creating a hole in the ozone layer. The hole in the ozone layer over the Antarctic in 1998 was “the largest observed since annual holes first appeared in the late 1970s.”10
CFCs were once used in aerosol sprays and as foam blowing agents. Their manufacture is now banned by an international treaty, the Montreal Protocol, signed by 160 nations. But because CFCs have a long atmospheric lifetime (about 50 years), those manufactured in the 1970s continue to damage the ozone layer today. The amount of CFCs in the stratosphere is now peaking. The good news is that scientists forecast that the ozone layer will return to its earlier, stable size by the middle of the 21st century—assuming that nations continue to comply with the treaty
Answer:
Global warming and ozone layer depletion are two different problems (see the sidebar “Misconceptions about Global Atmospheric Change” on page 95). Global warming is caused by the “greenhouse effect,” which is essential to life as we know it on planet Earth. Electromagnetic energy coming from the sun is absorbed by the Earth, which radiates some of this energy outward as infrared energy (heat). Some of this infrared energy escapes into space, but much of it is absorbed by “greenhouse gases” in the lower atmosphere (the troposphere) and is radiated back to the Earth as heat energy.