Environment

The images below show the Antarctic ozone hole on September 16 (the International Day for the Preservation of the Ozone Layer) in the years 1979, 1987, 2006, and 2011.

Stratospheric ozone is typically measured in Dobson Units (DU), which is the number of molecules required to create a layer of pure ozone 0.01 millimeters thick at a temperature of 0 degrees Celsius and an air pressure of 1 atmosphere (the pressure at the surface of the Earth). The average amount of ozone in Earth’s atmosphere is 300 Dobson Units, equivalent to a layer 3 millimeters (0.12 inches) thick — the height of 2 pennies stacked together.



In 1979 — when scientists were just coming to understand that atmospheric ozone could be depleted — the area of ozone depletion over Antarctica grew to 1.1 million square kilometers, with a minimum ozone concentration of 194 Dobson Units. In 1987, as the Montreal Protocol was being signed, the area of the hole reached 22.4 million square kilometers and ozone concentrations dropped to 109 DU. By 2006, the worst year for ozone depletion to date, the numbers were 29.6 million square kilometers and just 84 DU. By 2011, the most recent year with a complete data set, the hole stretched 26 million square kilometers and dropped to 95 DU.

The Antarctic hole seems to be stabilizing and may be slowly recovering. The focus of scientists now is to make sure that it is healing as expected. The amount of ozone-depleting substances (ODS) in the atmosphere has stopped rising in recent years, and may actually be decreasing. Changes in the ozone hole now are not significantly driven by changes in CFCs, but instead driven by year-to-year changes in weather in the stratosphere.

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Plans to open up a new Australian "coal export rush" could turn a single Queensland region into the seventh largest contributor of carbon dioxide emissions on the planet, undermining international efforts to keep global warming below 2C.

Nine proposed "mega mines" in the Galilee Basin would, at full capacity, result in 705m tonnes of CO2 released into the atmosphere. This level of emissions would surpass those of all but six nations in the world. By comparison, the UK emitted 549.3 million tonnes of CO2 from all sources in 2011.