Greenhouse Gases and Climate Change:
Is Carbon Dioxide a Problem?

William R. Kininmonth and George Fox

We are repeatedly told that human-induced carbon dioxide emissions are the principal cause of the current period of global warming and that continuing emissions will lead to dangerous climate change. This argument, which is based on a simple but erroneous hypothesis, is promoted by the Intergovernmental Panel on Climate Change (IPCC). However, like predictions of imminent resource exhaustion promulgated by the Club of Rome in 1972, it is just another false alarm.

This leaflet seeks to contribute to the scientific debate about climate change and to a wider understanding of its economic and social implications.

The climate system is complex and although we understand many of the causes of past climate change there continue to be significant unknowns. We do know that the temperature of the Earth is sustained by solar energy received mainly over the tropics. The global variations of temperature are driven and regulated by the transport of heat energy from the tropics to polar regions by atmospheric circulations and by ocean currents such as the Gulf Stream.

As far as greenhouse gases are concerned we know that:

1. The three major greenhouse gases that occur naturally in the atmosphere are water vapour, carbon dioxide and ozone. Of these, water vapour has by far the largest impact on climate. Its quantity and distribution throughout the atmosphere change significantly with time. Other greenhouse gases include methane, oxides of nitrogen and chlorofluorocarbons. The direct effect of greenhouse gases is to cool the atmosphere---these gases emit more radiation than they absorb.
2. The natural cooling of the atmosphere by greenhouse gases and radiation processes is offset mainly by the release of latent heat during rain formation.
3. The concentration of water vapour is a maximum in the tropics because of evaporation, particularly from the warm ocean surfaces. Water vapour is transported around the globe by the winds.
4. The Earth's surface is cooled as seawater evaporates. The rates of evaporation and loss of latent heat from the ocean surface increase exponentially as the temperature of the tropical ocean rises. This puts a practical upper limit on how warm the tropical oceans can get and explains why the warmest tropical ocean temperatures have remained more or less constant at about 30 ºC over the past thirty years.
5. Over the tropics, deep convection and energy exchange in the atmosphere directly link atmospheric temperatures to the temperature of the warmest ocean surfaces. Satellite and weather balloon data independently confirm that the tropical atmosphere has not warmed over the past thirty years, and this stability is consistent with the near constant temperature of the warmest surface waters.
6. While there is a natural upper bound to tropical temperatures, the temperatures over middle and higher latitudes are regulated by the rate of heat transport from the tropics. When averaged globally, temperatures have been slightly warmer than they are now. Also, the temperature of the Earth can cool significantly. Changes to ocean currents can lead to cooler tropical ocean temperatures and reduced heat transfers between the oceans and the atmosphere, thus leading to the onset of the next ice age.
7. Overall, greenhouse gases and the hydrological cycle (evaporation, transport of water vapour and precipitation) are essential for maintaining the Earth's surface at a temperature cooler than it would otherwise be, and they provide a powerful negative feedback mechanism.
8. Carbon dioxide naturally cycles through the atmosphere due to plant growth and decay; the total exchange in each direction is calculated to be about 120 Gigatonnes of carbon (GtC)[1] per year. Over the oceans, carbon dioxide is taken up by the cold surface waters of the polar regions and is returned to the atmosphere by the relatively warm upwelling waters over the tropics; the annual rate of exchange is about 90 GtC per year.
9. The annual emission of carbon dioxide to the atmosphere resulting from human activities is about 5 GtC per year and the human emissions are thus relatively small compared to the natural exchange processes. Atmospheric carbon dioxide contains about 730 GtC. Changes in natural exchanges, as well as human activities, have led to recent increases in atmospheric concentrations of carbon dioxide.
10. Before industrialisation took place in the West during the 19th century the atmospheric concentration of carbon dioxide was about 280 ppm.[2] The total concentration of carbon dioxide has risen to about 380 ppm through changes to both natural exchange processes and human activities.
11. Carbon dioxide emissions attributable to human activities in Australia are about 1.5 per cent of the total world emissions from human activities.
12. Carbon dioxide is not a pollutant. It is basic to photosynthesis and encourages plant, tree and marine growth. Millions of years ago, when there was a much higher concentration of carbon dioxide in the atmosphere than now, forest growth increased dramatically and eventually decayed to form extensive coal deposits. (Carbon dioxide should not be confused with carbon monoxide, an extremely poisonous gas that will cause death in small concentrations.)

Reducing carbon dioxide emissions due to human activities.

Replacement of coal-fired electricity production by wind power generation has not been economical. Total wind-generated electricity has not yet reached half of one per cent of world electricity production and the cost per unit of wind-powered electricity generation is up to three times the cost of production from coal-fired plant. In addition, alternative backup power generation would be needed for periods of low wind and for periods of high wind when the wind generators have to be shut down.

The technology of capturing carbon dioxide emissions from power stations and then burying this CO2 underground has been investigated. The cost of such carbon capture and geo-sequestration from all Australian power stations would be many billions of dollars.

Other influences on Earth's temperature

The Earth is slowly cooling as heat from the core is conducted to the surface. Heat is also released during volcanic eruptions but the magnitudes of both are relatively small on the global scale.

The main source of heat for Earth is the nuclear furnace of the Sun. As the intensity of the Sun's radiation varies so too will the heat received by Earth. The net heat received at the Earth's surface also varies with the periodically changing orbital characteristics relative to the Sun, the atmospheric aerosol concentration (especially those aerosols released during volcanic eruptions) and the variations of cloudiness (especially with changing cosmic ray activity).

Earth's temperature cycles

The recent rate of warming and the current global average temperature have been exceeded in the past. There is ample evidence from navigation and colonisation records that Arctic regions at least were warmer about 1,000 years ago, and proxy records indicate that the Earth was warmer between 8,000 and 4,000 years ago. The current relatively warm period that has lasted more than 8,000 years (the Holocene) is typical of the abrupt periods of warming (interglacials) that have punctuated the generally glacial conditions of the past several million years.

Worldwide, the peripheries of polar ice sheets and mountain glaciers have been melting for more than 150 years. This melting is consistent with increased solar radiation since the early 1700s. Solar activity has continued to increase over recent decades, albeit not steadily.

Weather and Climate

There is no evidence of increased frequency of droughts, floods, tropical cyclones, middle latitude storms or other violent weather activity as Earth has warmed by about 0.6 ºC during the 20th century. Claims that such changes will occur in the future are conjecture based largely on the output of rudimentary computer models. Over South East Australia the most intense heat wave since weather records commenced continues to be the event that brought record temperatures to Adelaide, Melbourne and Sydney, and disastrous bushfires throughout South-Eastern Australia, in January 1939.

Conclusion

We rely on the Sun for warmth, and water vapour (the principal greenhouse gas) ensures that we have a reasonably equable climate. The effect on climate of human-induced carbon dioxide emissions is negligible.

Notes

1. A Gigatonne of carbon (GtC) is 1000 million tonnes of carbon.
2. ppm is parts per million by volume.

About the Authors

The Statement on the previous pages has been jointly prepared by:

• Mr William R. Kininmonth M.Sc., M.Admin., Dip. Met.---has had a career in meteorological science and policy spanning more than 40 years. From 1986 to 1998 he headed Australia's National Climate Centre, monitoring Australia's changing climate and advising government on the extent and severity of climate extremes. He coordinated the scientific and technical review of the 1997-98 El Niño event for the World Meteorological Organization and its input to the United Nations Task Force on El Niño. As a member of Australia's delegations to the Second World Climate Conference (1990) and the subsequent negotiations for the United Nations Framework Convention on Climate Change (1991-92) he had a close association with the early developments of the climate change debate.

William Kininmonth's book, Climate Change: A Natural Hazard (Multi-Science Publishing Co., UK) was launched in Melbourne in 2004. He lives in Kew, in Victoria, Australia, and can be contacted at: w.kininmonth@bigpond.com

• Mr E.C. 'George' Fox AM, B.Sc., B.E. --- a 'Professional Engineer' with 60 years experience, including 4 years Army service during WW2 and 25 years with English Electric Company, makers of heavy electric power generation, distribution and utilisation plant, locomotives and aircraft who employed 100,000 people worldwide. He was their General Manager for India for 3 1/2 years then their CEO for Australia for over 9 years with a 2,000 strong workforce obtaining contracts for 5,000MW of power generating plant and over 300 diesel electric locomotives and many other items for governments, mines and industry around Australia. This was followed by Directorships on 12 company Boards over more than 30 years that involved about 15 round-the-world travels to see the world's major coal and gas fired, nuclear and hydro-electric power stations. He lives in Pymble, NSW, Australia.