Le 21 mai 2014, 05:25 dans Humeurs • 0
It was reportedearlier Fut Coins that the hole was expected to be large this year,but a recent paper in Nature is the first to fully analysethe extent of the phenomenon.
The blame has been pinned on cold temperatures. The level ofozone in the atmosphere varies depending on temperature, as thechlorine compounds that break the ozone down are most active atlower temperatures. This year didnt break any low-temperaturerecords in the Arctic, but the upper-air region where the ozonesits stayed chilly for an unusually long time over an unusuallylarge area.
It was continuously cold from December through April, and thathas never happened before in the Arctic in the instrumental record, said Michelle Santee fromNasa Jet Propulsion Laboratory. Why all this occurred willtake years of detailed study.
On the bright side, the root cause of this problem --anthropogenic CFC emissions -- were successfully restricted in 1987by the Montreal Protocol, and eventually eliminated in a rare caseof international co-operation over atmospheric science. It justthat the chlorine compounds that were emitted prior to therestrictions being implemented can persist for a long time in theupper atmosphere. The ozone layer is on its way back to health, andisnt expected to get any better before the middle of the century,but at least it isnt getting much sicker.