The most obvious cause for concern about ozone loss stems from its role as a filter of the Sun’s ultra-violet radiation.Concentrating on the YV region, it could be noticed that the ban labelled UV-C(2.0-2.9×10-7m) is virtually eliminated by the atmospjere. This is just as well, because UV-C is lethal to micro-organisim(where its use is in germicidal lamps), and can destroy both nucleic acids and proteins: in the range from 2.4-2.9x10m, protection from UV-C is due entirely to absorption by ozone.
More important as far as ozone loss is concerned is the narrow band bwtween 2.9 x10-7 and 3.2×10-7, known as’ biologically active UV or UV-B . Here the attenuation of the solar input is evident due to ozone, but theeffect is less complete: a fraction of UV-B penetrates all the way to the ground. UV-B radiation is known to have a multitude of effects on humans, animals, plants and materials and indeed on the chemistry of the of the atmosphere itself. Most of these effects are damaging – but few are sufficiently well understood at present for the impact of enhanced UV-B to be quantified. However, given its importance, it may still come a a surprise to learn that there were few reliable measurements f this radiation band untill the the late 1980’s. Part of the reason is its low intensity: at the edge of the Earth’s atmosphere it represents about 2%of the sola spectrum, but only a small fraction of this reaches the surface of the Earth.’
December 3, 2013 at 7:46 pm |
There are strong interactions between ozone depletion and changes in climate induced by increasing greenhouse gases (GHGs). Ozone depletion affects climate, and climate
change affects ozone. The successful implementation of the Montreal Protocol has had a marked effect on climate change. Calculations show that the phase-out of chlorofluorocarbons (CFCs) reduced Earth’s warming effect (i.e., radiative forcing) far more than the measures taken under the Kyoto protocol for the reduction of GHGs. The amount of stratospheric ozone can be affected by the increases in the concentration of GHGs, which
lead to decreased temperatures in the stratosphere and accelerated circulation patterns, which tend to decrease total ozone in the tropics and increase total ozone at mid and high latitudes. Changes in circulation induced by changes in ozone can also affect patterns of surface wind and rainfall.
December 3, 2013 at 11:11 pm |
Scientific evidence indicates that stratospheric ozone is being destroyed by a group of manufactured chemicals, containing chlorine and/or bromine. These chemicals are called “ozone-depleting substances” (ODS).
ODS are very stable, non-toxic and environmentally safe in the lower atmosphere, which is why they became so popular in the first place. However, their very stability allows them to float up, intact, to the stratosphere. Once there, they are broken apart by the intense ultraviolet light, releasing chlorine and bromine. Chlorine and bromine demolish ozone at an alarming rate, by stripping an atom from the ozone molecule. A single molecule of chlorine can break apart thousands of molecules of ozone.
What’s more, ODS have a long lifetime in our atmosphere — up to several centuries. This means most of the ODS we’ve released over the last 80 years are still making their way to the stratosphere, where they will add to the ozone destruction.
December 5, 2013 at 10:11 pm |
Speaking of nature doing its job, trees produce large amounts of water vapor, a major greenhouse gas and are a huge contributor to global warming. So again, nature has a way of fixing itself, by having these pine beetles eat up a bunch of the trees so it can reduce the greenhouse gasses and return itself to more conducive temperatures as its defense against the sun.