Jagged Environment
Lifting the lid
|
Jagged EnvironmentLifting the lid |
||||
|
Mass extinctions |
This is a perfect example of a gradient (global warming) creating a new boundary (stratospheric-ice), which then furnishes a mechanism to relieve the former: i.e. the tropospheric lid is lifted. Like an active volcano, Nature provides a means for the steady release of pressure (the driving-force behind the gradient). The gases in the lower atmosphere are kept in place mainly by the temperature inversion at the tropopause, which is where the stratosphere begins. This is the region where the atmosphere, initially cooling increasingly on ascending from the surface of the Earth, suddenly begins to warm-up. The cause of this is the ozone-layer. Ozone absorbs UV light from the Sun, so acting as a shield which protects life on the Earth’s surface, and in so doing, heats-up. This layer of hot gas acts as a lid on the gases present in the lower, cooler regions, and prevents these cooler gases from escaping into the higher atmosphere. The amount of ozone depends on the UV intensity in this region of the atmosphere and on the oxygen concentration. The ozone balance is also influenced by how much ice is available in the stratosphere, which is where the ozone mainly is. Ironically, it has been suggested that global-warming may be causing the atmosphere to cool. This is because the increasing level of CO2 absorbs heat radiation from the Earth’s surface, and reduces the temperature of the stratosphere. So, while the lower atmospheric levels warm, the higher levels cool, and cloud formation increases in these cooling atmospheric regions. The increased cloud surface area is believed to be responsible for the sudden and further rapid ozone-loss, not just from the Antarctic, but now over Europe. This further loss of ozone will cause further stratospheric cooling and hence cloud formation, resulting in a spiral loss of ozone. Once a sufficiently low temperature has been reached, the lid, which is normally provided by the “hot” ozone layer will be lifted. Since this lid normally keeps greenhouse gases (particularly CO2) in the lower atmospheric regions, then greenhouse gases will then escape, so reducing the extent of cloud formation and encouraging the restoration of normal ozone levels. This ultimately reassuring scenario may, however, be intercepted in a less humanly benevolent way, since a more violent climate is likely. Copyright © 2001 Chris James Last updated 12 March, 2005 |
||||