The Montreal Protocol to protect the ozone layer is humanity ’s outstanding environmental succeeder . Since it was pass in 1987 , the assiduousness of most of the gasses threatening our atmospherical carapace has fall , and the ozone layer hasstarted to recover . However , the descent in a key ozone - depleting accelerator pedal has slowed , suggesting there is some illegal source . At current rates , this will obstruct the recovery of the Earth ’s sunscreen , causing 1000 of superfluous compositor’s case of skin genus Cancer . If these secret emissions increase further , they could model a threat to us all .
Trichlorofluoromethane ( CFC-11 ) was one of the gaseous state phased out under the Montreal Protocol to protect the ozone layer . Nevertheless , a quarter of the ozone - destroying Cl in the stratosphere come from this one industrial gas . The concentration of CFC-11 in the standard pressure fell steadily from 2002 to 2012 at a pace of 2.1 parts per trillion per year , but a squad from the National Oceanic and Atmospheric Administration write up inNaturethat since then it has been worsen only half as quickly .
CFC-11 has an atmospheric lifespan of around 43 - 67 years , so it should be decreasing quicker than this . Some stocks invent before the ban have been reaching the air as buildings comprise CFC-11 product are demolished , but this should n’t be accelerating . There is a widening interruption between concentrations in the northerly and Southern Hemisphere , a sure sign of increased emissions north of the equator . Most other ozone destroyers are continuing to fall in logical argument with expectations .
After accounting for changes in atmospherical circulation that exaggerated the job , the source estimate that at least 7,000 tonnes ( 7,700 tons ) of fresh CFC-11 is being produced each yr , despite prescribed production being almost zero .
The paper does n’t attempt to identify the sources , but there are hints they lie in East Asia .
A decade after chemist first warned of the danger that chlorine - containing gasses could pose to the ozone layer , which protects the Earth from ultraviolet radioactivity intense enough to drink down most living things if it reached the open , the reality settle to do .
The chemicals in question were phased out . yield of CFC-11 – which before the prohibition had been used as a refrigerant , propellent in atomiser cans , and for blowing foam – was to give up by 2010 . fall concentrations of CFC-11 in the atmosphere accounted for much of the onward motion made in reversing the declension in ozone level over Antarctica . Without this restoration , the ecosystem of the Southern Ocean , the base of much of the marine food entanglement , would have been at risk of collapse .
Besides its ozone - depleting capacity , CFC-11 is the fifth most of import causa of global heating , although far behind atomic number 6 dioxide and methane . Since replacements are available for all its know manipulation , its revitalisation is presumptively to save costs .
