Information for Action

The Greenhouse Effect and Climate Change

The history of climate change

The physics of how greenhouse gases warm the atmosphere has been known for well over a century. The subject did not however become generally known until the late 1980s. Some of the pioneers of greenhouse theory include Sir Crispin Tickell (Climate Change and World Affairs 1986), Stephen Schneider (Global Warming, 1989), Fred Pearce (Turning up the Heat, 1989), John Gribbin (Hothouse Earth, 1990), Jim Hansen (Climate Change 2005) and James Lovelock (The Revenge of Gaia 2006).

In 1988 Jim Hansen of the NASA Goddard Institute of Space Studies warned the United States Senate of the dangers of global warming. In 1989 climatologist Sir Crispin Tickell pushed for the formation of the Intergovernmental Panel on Climate Change (IPCC). Under the chairmanship of Professor Bert Bolin the IPCC started the data gathering and model building that was the basis for forecasts of future climates. British scientists Lord May and Sir David King have been powerful advocate for action on climate change.

Change is a normal part of geological history and over millions of years the Earth has undergone many different extremes of climate – global warmings and ice ages. The most recent period of warming occurred fifty-five million years ago at the beginning of the geological period called the Eocene and this lasted for 200,000 years.

In contrast to these long time spans, human civilisation has only existed for a relatively short period. Our history falls within a relatively warmer period of geological history since the last ice age 12,000 years ago and we have adapted to this environment.

The Earth's temperatures in the past have always been related to atmospheric carbon dioxide concentration. High carbon dioxide levels were associated with warm climates and low carbon dioxide levels were associated with cold climates. In earlier geological periods, global warming may have been caused by the release of greenhouse gases from volcanoes or an increase breakdown of plants. What is unusual about the current global warming period is that we are the cause of it.

The concentration of greenhouse gases in the atmosphere, particularly carbon dioxide, is increasing. About 200 years ago the concentration of carbon dioxide in the atmosphere was 250 parts per million (ppm). Now it is over 380 ppm. It is increasing steadily at a rate of about 0.3 - 0.4% per year and is likely to exceed 550 ppm in the next few decades. According to the IPCC, 500 ppm represents a temperature rise of about 3°C. Since carbon dioxide is chemically inert, man made excesses are not consumed by photochemical or chemical processes in the atmosphere. If nothing is done, the European Environment Agency predicts the concentration of carbon dioxide could rise to 1,350 ppm by 2100.

Most scientists with knowledge on the subject accept climate change as a fact. It has also been taken seriously enough by most of the world's governments for an international treaty, known as the Kyoto protocol to be implemented.

Dealing with the causes of climate change means big changes in the way we conduct economic activities. This is seen as threatening by some businesses, so there is a lot of political resistance to implementing appropriate measures. Some countries still refuse to sign the Kyoto protocol, most notably the U.S.A., which is by far the largest producer of greenhouse gases in the world.

The USA and Australian governments have not signed up to the Kyoto agreement partly because they have large coal reserves and want to continue using coal-fired power stations. The USA has enough reserves of coal to last 250 years at current rates of consumption. It argues that its coal-fired power plants are cleaner than they used to be because they no longer emit sulphur dioxide and other pollutants, however they still produce the same amounts of carbon dioxide.

Instead, the USA and Australia are participating in the Asia-Pacific Partnership on Clean Development and Climate which was established in January 2006. The partnership includes the heavily industrialised countries of Japan and South Korea and the rapidly growing ones of China and India. The focus will be on trading technology. In contrast to the Kyoto agreement, there are no emission control targets. Skeptics say that the funds committed for the development of new and renewable energy technologies are not enough.

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