Levels of stratospheric ozone
This indicator measures concentrations of stratospheric ozone over New Zealand. These New Zealand measurements are used to provide information on the condition of the ozone layer over mid-latitudes in the southern hemisphere.
Stratospheric ozone levels are measured over Lauder in Central Otago, as ‘total column ozone’: the total amount of ozone in a column of air from the earth’s surface to the top of the atmosphere. Data is used to illustrate the degree of ozone depletion, or how fast the ozone layer may be recovering over New Zealand.
Did you know?
- Ozone is a gas present in trace quantities in the atmosphere.
- More than 90 per cent of ozone is found in the stratosphere, 10–25 kilometres above the earth, in what is known as the ozone layer.
- Ozone plays an important role in protecting the earth from the sun’s harmful effects.
- Although ozone is constantly created and destroyed in the stratosphere through natural processes, some chemicals increase the amount of ozone destroyed such as chlorofluorocarbons (CFCs).
Current situation and long-term trends
Stratospheric ozone levels in New Zealand have changed considerably over time. Levels have stabilised in the last decade, reversing decreases in the 1980s and 1990s. The figure below shows this trend. This trend aligns with what has been recorded internationally.
Figure 1: Average yearly ozone concentrations over New Zealand, 1970–2011
Note:
Five-year averages have been plotted to give an indication of trend in ozone concentration.
Source: National Institute of Water and Atmospheric Research.
Read a description of this figure
| Year ended December | Average yearly ozone level | 5-yearly moving average |
|---|---|---|
| 1970 | 319.6 | n/a |
| 1971 | 314.0 | n/a |
| 1972 | 327.5 | n/a |
| 1973 | 317.3 | n/a |
| 1974 | 320.6 | 319.8 |
| 1975 | 313.8 | 318.6 |
| 1976 | 307.5 | 317.3 |
| 1977 | 319.0 | 315.6 |
| 1978 | 314.1 | 315.0 |
| 1979 | 322.8 | 315.4 |
| 1980 | 314.6 | 315.6 |
| 1981 | 315.4 | 317.2 |
| 1982 | 315.6 | 316.5 |
| 1983 | 317.1 | 317.1 |
| 1984 | 318.7 | 316.3 |
| 1985 | 297.4 | 312.8 |
| 1986 | 306.5 | 311.0 |
| 1987 | 304.3 | 308.8 |
| 1988 | 304.1 | 306.2 |
| 1989 | 308.8 | 304.2 |
| 1990 | 302.5 | 305.2 |
| 1991 | 313.0 | 306.5 |
| 1992 | 311.6 | 308.0 |
| 1993 | 302.3 | 307.6 |
| 1994 | 312.2 | 308.3 |
| 1995 | 306.7 | 309.1 |
| 1996 | 309.6 | 308.5 |
| 1997 | 293.0 | 304.7 |
| 1998 | 304.9 | 305.3 |
| 1999 | 293.7 | 301.6 |
| 2000 | 299.8 | 300.2 |
| 2001 | 309.7 | 300.2 |
| 2002 | 310.4 | 303.7 |
| 2003 | 310.4 | 304.8 |
| 2004 | 302.4 | 306.5 |
| 2005 | 309.7 | 308.5 |
| 2006 | 299.6 | 306.5 |
| 2007 | 308.1 | 306.0 |
| 2008 | 296.2 | 303.2 |
| 2009 | 308.0 | 304.3 |
| 2010 | 306.3 | 303.6 |
| 2011 | 306.3 | 305.0 |
Ozone-depleting substances
In the latter part of the 20th century, human activities began producing ozone depleting substances. These chemicals were widely used in refrigerators, air conditioners, fire extinguishers and electronic equipment, as solvents for cleaning (including dry cleaning) and as agricultural fumigants.
Significant efforts have occurred internationally to improve ozone concentrations by reducing the emissions of ozone depleting substances. Much of this effort has been achieved through the Montreal Protocol. The atmospheric abundance of most of the major ozone depleting substances controlled by the Montreal Protocol are declining.
New Zealand does not produce any ozone depleting substances but has made significant reductions in its consumption of these substances by phasing out their use. The figure below shows the reduction in the global and New Zealand consumption of ozone depleting substances controlled by the Montreal Protocol.
Figure 2: Total reported consumption of ozone depleting substances
Read a description of this figure
| Year | New Zealand consumption (ozone depleting potential tonnes) | Global consumption (ozone depleting potential tonnes) |
|---|---|---|
| 1990 | 1.195 | 978.0 |
| 1991 | 0.837 | 894.3 |
| 1992 | 0.722 | 859.9 |
| 1993 | 0.859 | 767.2 |
| 1994 | 0.460 | 491.9 |
| 1995 | 0.323 | 407.3 |
| 1996 | 0.099 | 293.0 |
| 1997 | 0.080 | 270.0 |
| 1998 | 0.050 | 338.2 |
| 1999 | 0.068 | 287.7 |
| 2000 | 0.019 | 263.2 |
| 2001 | 0.032 | 208.0 |
| 2002 | 0.043 | 162.8 |
| 2003 | 0.035 | 170.6 |
| 2004 | 0.033 | 126.5 |
| 2005 | 0.042 | 92.6 |
| 2006 | 0.038 | 86.5 |
| 2007 | 0.027 | 61.4 |
| 2008 | 0.017 | 43.4 |
| 2009 | 0.017 | 48.7 |
| 2010 | 0.012 | 43.5 |
This information has come from the indicator update on stratospheric ozone.
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Last updated: 21 May 2013
