4 January 2018, Geophysical Research Letters, Decline in Antarctic Ozone Depletion and Lower Stratospheric Chlorine Determined From Aura Microwave Limb Sounder Observations. The Antarctic ozone hole is healing slowly because levels of the man-made chemicals causing the hole have long lifetimes. We use Microwave Limb Sounder (MLS) satellite data to measure O3 over Antarctica at the beginning of winter and then compare it to O3 near the end of winter to calculate depletion. During this period, nearly all O3 change is due to depletion. MLS also measures HCl, and when ozone levels are very low, nearly all the reactive chlorine species (Cly) are converted to HCl. Clyvaries a lot from year to year from atmospheric motions. Fortunately, MLS measures nitrous oxide (N2O), a long-lived gas that also varies with the motions. Using the ratio of Cly to N2O, we find that there is less chlorine now than 9 years ago and that Cly has decreased on average about 25 parts per trillion/yr (0.8%/yr). The O3 depletion we calculate from MLS data responds to changes in the Clylevels, and the ratio of the change in ozone loss to the change in Cly matches model calculations. All of this is evidence that the Montreal Protocol is working—the Cly is decreasing in the Antarctic stratosphere and the ozone destruction is decreasing along with it. Read More here
Tag Archives: Antarctica
12 October 2017, BBC News, Ozone layer recovery could be delayed by 30 years. Rising global emissions of some chlorine-containing chemicals could slow the progress made in healing the ozone layer.A study found the substances, widely used for paint stripping and in the manufacture of PVC, are increasing much faster than previously thought. Mainly produced in China, these compounds are not currently regulated. Experts say their continued use could set back the closing of the ozone hole by up to 30 years. Scientists reported last year that they had detected the first clear evidence that the thinning of the protective ozone layer was diminishing. The Montreal Protocol, which was signed 30 years ago, was the key to this progress. It has progressively helped governments phase out the chlorofluorocarbons and the hydrochlorofluorocarbons that were causing the problem. However, concern has been growing over the past few years about a number of chemicals, dubbed “very short-lived substances”. Antarctic ozone hole starts to ‘heal’ How Arctic ozone hole was avoided Weather ‘behind ozone hole changes’ Dichloromethane is one of these chemicals, and is used as an industrial solvent and a paint remover. Levels in the atmosphere have increased by 60% over the past decade. Read More here
12 October 2017, BBC News, Ozone layer recovery could be delayed by 30 years. Rising global emissions of some chlorine-containing chemicals could slow the progress made in healing the ozone layer.A study found the substances, widely used for paint stripping and in the manufacture of PVC, are increasing much faster than previously thought. Mainly produced in China, these compounds are not currently regulated. Experts say their continued use could set back the closing of the ozone hole by up to 30 years. Scientists reported last year that they had detected the first clear evidence that the thinning of the protective ozone layer was diminishing. The Montreal Protocol, which was signed 30 years ago, was the key to this progress. It has progressively helped governments phase out the chlorofluorocarbons and the hydrochlorofluorocarbons that were causing the problem. However, concern has been growing over the past few years about a number of chemicals, dubbed “very short-lived substances”. Antarctic ozone hole starts to ‘heal’ How Arctic ozone hole was avoided Weather ‘behind ozone hole changes’ Dichloromethane is one of these chemicals, and is used as an industrial solvent and a paint remover. Levels in the atmosphere have increased by 60% over the past decade. Read More here
12 July 2017, New York Times, An iceberg the size of Delaware just broke away from Antarctica. A chunk of floating ice that weighs more than a trillion metric tons broke away from the Antarctic Peninsula, producing one of the largest icebergs ever recorded and providing a glimpse of how the Antarctic ice sheet might ultimately start to fall apart. A crack more than 120 miles long had developed over several years in a floating ice shelf called Larsen C, and scientists who have been monitoring it confirmed on Wednesday that the huge iceberg had finally broken free. There is no scientific consensus over whether global warming is to blame. But the landscape of the Antarctic Peninsula has been fundamentally changed, according to Project Midas, a research team from Swansea University and Aberystwyth University in Britain that had been monitoring the rift since 2014. “The remaining shelf will be at its smallest ever known size,” said Adrian Luckman, a lead researcher for Project Midas. “This is a big change. Maps will need to be redrawn.” Read More here