(Image: NASA Earth Observatory )
- Ozone (O3) in the lower atmosphere (troposphere)(Fig. 1) absorbs some infrared energy from earth, re-radiating it in the atmosphere. It’s short-lived and entirely due to man-made emissions—including methane, nitrous oxide, and carbon monoxide—mostly pollution in cities, so its concentration varies enormously in different places and over different times and seasons.
- It’s important to note that while ozone is a greenhouse gas in the lower atmospher, without ozone in the upper atmosphere (stratosphere)(Fig. 1), the DNA of plants and animals would be so damaged that life on the surface of the Earth would be unable to exist. Unfortunately, in spite of an international agreement to stop using ozone-depleting gasses, the hole in the ozone layer over the Arctic grew to a record size in 2020 (top image).
- This underscores the point that the location of where some gasses are in the atmosphere plays a pivotal role in calculating their global warming potential. It also underscores the point that greenhousse gasses are not in inherently ‘bad’, but too many (or too few) in the wrong location because of human activities, causes problems for life on Earth.
“Ozone is present in two different areas of the atmosphere and plays two different roles. It is produced naturally in the outer layers of the atmosphere (the stratosphere) very high above earth. This stratospheric ozone helps protect the planet from the Sun’s ultraviolet rays which can damage our skin and health. This ozone is typically known as the ozone layer.
“Although ozone is vital in the stratosphere, here at the Earth’s surface it is a pollutant which can damage our health and the environment.
“At the Earth’s surface, ozone is not directly emitted but is formed by reactions of other pollutants such as nitrogen oxides and volatile organic compounds (VOCs), and sunlight. This is known as a photochemical reaction and often produces photochemical smog.
“The primary pollutants are produced mainly from motor-vehicle emissions and other combustion sources, and industrial and domestic use of solvents and coatings.
“Auckland, Hamilton and Christchurch have the highest potential for ozone pollution.” – NZ Ministry for the Environment
References and further reading
- Ministry for the Environment: New Zealand’s Greenhouse Gas Inventory 1990–2017 Vol 1; Chapters 1-15
- Ministry for the Environment: New Zealand’s Greenhouse Gas Inventory 1990–2017: graphic
- Ministry for the Environment: 2019 Measuring Emissions: A Guide for Organisations
- Ministry for the Environment: 2019 Measuring Emissions: A Guide for Organisations. 2019 Summary of Emission Factors
- Ministry for the Environment: New Zealand’s Greenhouse Gas Inventory
- NOAA: Global Monitoring Laboratory Earth System Research Laboratories
- UCAR Center for Science Education: The troposhere
- 2021 Vollmer et al; Unexpected nascent atmospheric emissions of three ozone-depleting hydrochlorofluorocarbons,
- 2020 Polvani et al; Substantial twentieth-century Arctic warming caused by ozone-depleting substances Nature Climate Change 10, 130-133
- 2020 WMO (World Meteorological Organization): Arctic ozone depletion reached record level
- 2019 IPCC: Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories
- 2018 IPCC: Chapter 4, Atmospheric Chemistry and Greenhouse Gases
- 2013 IPPC: Chapter 8: Anthropogenic and Natural Radiative Forcing in: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change