Ďaľšie referáty z kategórie
|Referát vhodný pre:||Stredná odborná škola||Počet A4:||2.3|
|Priemerná známka:||3.00||Rýchle čítanie:||3m 50s|
|Pomalé čítanie:||5m 45s|
That means that even if civilization stops any CFCs use and release immediately, most of them are just on their way at this time and therefore the ozone depletion process will take much longer. Some measurements and predictions say that it will last several decades or maybe even centuries until all the chlorine will be removed. It is quite a long period, in my opinion, when we realize that we made the pollution in half a century. And it is really us – the civilization - who made it because only 15% of the CFCs released in the past were produced in natural ways (mostly by certain marine species) and the other 85% were a consequence of civilization “mistakes”.
There are two general ways of stopping the ozone depletion immediately: firstly, cut of producing and using freons and halons and, secondly, somehow “clearing” the air from substances already being released. Since the years 1984 and 1985, when the ozone hole over Antarctica was firstly observed and measured, a lot of assessments were signed. Fortunately, most of them have played their role - the greater part of CFCs production has been stopped. On the other hand, as mentioned upper, greater part of the CFCs are still wandering somewhere in the air. However, the presence of hydrogen in replacement compounds for CFCs - hydrochlorofluorocarbons (HCFCs) – makes them very reactive with chlorine, which could so be stopped before reaching the stratosphere. Hopefully this is the right way how to at least lower the bad consequences of the ozone depletion.
After more than fifty years, civilization finally did something against ozone depletion. Too late? Maybe. Many scientists say that ozone depletion is really rooted out already, in opposition of the greenhouse effect, for instance. We are just waiting for the “last” more 85% of the CFCs to make their attack….
|Ozone depletion||SOŠ||2.9867||622 slov|