Human-Induced Atmospheric Change: the Ozone Hole
The Earth is so big that many people often have a hard time believing that we humans can have any sort of real, lasting impact on it. A good example of how humans can and do impact the Earth and its systems is the development and subsequent rates of growth of the ozone hole in the southern hemisphere.
The ozone hole is not really a "hole", it is an area over the South Pole where there is a significant decrease in the density of ozone molecules in the stratosphere, the layer of the atmosphere where ultraviolet radiation reacts with oxygen molecules to produce ozone.
The ozone hole was growing at a rapid pace during the latter half of the 20th century due to the high use of CFC as refrigerants. Once the Montreal Protocol was passed in 1978, the rate of CFC emissions into the atmosphere decreased drastically, but the ozone depletion continued due to the high level of CFCs already in the atmosphere. In the last decade, however, scientists have measured a decrease in the rate at which the ozone hole is growing -- a sign that it is stabilizing. It will likely be another 50 to 100 years before the ozone hole recovers and the amount of UV light reaching Earth's surface decreases again.
Assignment
Log into BBLearn, click on Module 1, and choose Mastering Assignments. Answer the questions about ozone formation and depletion by CFCs by completing "Assignment 1.2: Ozone Depletion."
The ozone hole is not really a "hole", it is an area over the South Pole where there is a significant decrease in the density of ozone molecules in the stratosphere, the layer of the atmosphere where ultraviolet radiation reacts with oxygen molecules to produce ozone.
The ozone hole was growing at a rapid pace during the latter half of the 20th century due to the high use of CFC as refrigerants. Once the Montreal Protocol was passed in 1978, the rate of CFC emissions into the atmosphere decreased drastically, but the ozone depletion continued due to the high level of CFCs already in the atmosphere. In the last decade, however, scientists have measured a decrease in the rate at which the ozone hole is growing -- a sign that it is stabilizing. It will likely be another 50 to 100 years before the ozone hole recovers and the amount of UV light reaching Earth's surface decreases again.
Assignment
Log into BBLearn, click on Module 1, and choose Mastering Assignments. Answer the questions about ozone formation and depletion by CFCs by completing "Assignment 1.2: Ozone Depletion."