Will enviros try to expand the Montreal Protocol to cover carbon dioxide emissions?
There is no ozone hole anywhere. Only transient thinning. The cause(s) of this phenomenon is anybody’s guess.
The abstract for the Geophysical Research Letters study is below.
4. Record Arctic ozone depletion could occur again
In the winter of 2010-2011, ozone levels above the Arctic declined to record lows, creating the first Arctic ozone hole, similar to the well-known Antarctic ozone hole. Scientists believe the ozone depletion was due partly to unusually cold temperatures in the stratosphere above the Arctic, as colder stratospheric temperatures make ozone-destroying chemicals such as chlorine more active. As global climate change continues, the Arctic stratosphere is expected to get colder, but levels of ozone-destroying chemicals should decline, as emissions of these chemicals were banned by the Montreal Protocol.
To try to learn more about Arctic ozone dynamics and determine whether the Arctic ozone hole is likely to recur, Sinnhuber et al. looked at satellite observations of temperature, ozone, water vapor, and chemicals that affect ozone in the Arctic atmosphere. They also used a model to determine how sensitive ozone levels are to stratospheric temperatures and chemistry. They find that their model accurately reproduced measured conditions. Their model suggests that stratospheric temperatures 1 degree Celsius (1.8 degrees Fahrenheit) lower than in the 2010-11 winter would result in locally nearly complete ozone depletion in the Arctic lower stratosphere with current levels of chemicals. A 10 percent reduction in ozone- depleting chemicals would be offset by a 1 degree Celsius decrease in stratospheric temperatures. The researchers conclude that although ozone-depleting substances should decline in coming decades, temperature changes could offset those effects, potentially leading to future severe Arctic ozone depletions similar to that during the winter of 2010-11.
Source: Geophysical Research Letters, doi:10.1029/2011GL049784, 2011
Title: Arctic winter 2010/2011 at the brink of an ozone hole
Authors: B.-M. Sinnhuber, G. Stiller, R. Ruhnke, T. von Clarmann, and S. Kellmann: Institute for Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany;
J. Aschmann: Institute of Environmental Physics, University of Bremen, Bremen, Germany.