How serious is the greenhouse effect?

How serious is the greenhouse effect?

By Dr Bob Hunter
At a meeting in Berlin earlier this year to review progress on the response of the developed nations to the greenhouse problem, Australia came in for some heavy criticism. That criticism has been revived recently (Sydney Morning Herald, August 7) with the news that the Australian Bureau of Agricultural and Resource Economics (ABARE) is hatching a report which defends the continued extensive use of coal for electricity generation. Australia is the world's largest exporter of coal and probably consumes more coal per head for electricity generation than any other country. Coal burning is one of the major contributors to greenhouse gas formation, so we Australians are making a disproportionate contribution to the effect and the possible environmental and climatic consequences.
This year's Templeton Lecture, on September 14, will be given by Dr Barrie Pittock of the CSIRO on the question "How 'dangerous' is climate change?". On the following morning (September 15), we plan to hold a symposium on Australia's response to the greenhouse effect, and to ask the question: is it enough?
From about 9000 years ago up till about 5000 years ago was the warmest period in recent climatic history. That is regarded by geologists as the "climate optimum", when the summer temperatures within the northern continents were several degrees higher than they are now.
However, even if that again produced very favourable conditions for plant growth, there is a strong possibility that it would produce profound changes to the ecosystem and to human communities.
For one thing, in Africa and Asia, the monsoons were also more intense then and they would probably be so again. Those earlier changes were not caused by carbon dioxide but probably by slight changes to the earth's orbit around the sun.
There is no doubt that the amount of carbon dioxide we are pumping into the atmosphere is causing the concentration to increase, and the likely result of that is an increase in the average temperature. Other gases, particularly methane, are important contributors to the effect and methane, too, is on the increase.
How big is the effect likely to be? No-one can answer that question yet, but strenuous efforts are being made to get the best possible estimate.
The calculation requires a very sophisticated mathematical description of the way the heat energy from the sun gets itself redistributed and how that will be affected by an increase in the level of greenhouse gases. Even the biggest computer facilities are up against it with calculations of this magnitude.
There are some scientists who are arguing that there is no evidence yet that there has been or will be any increase in temperature in the foreseeable future. That uncertainty makes it hard to convince the politicians that they should risk their voter support with drastic and expensive steps to cure a problem which might not be as serious as some people are making out.
Another difficulty is that the steps which can be taken by the affluent nations to reduce their emissions will be offset by the rises in emissions from the Third World countries as they increase their energy usage to improve their standard of living. We cannot deny them that right.
Is there nothing we can do then?
Certainly there are some win-win strategies — steps which would reduce the problem with no obvious cost. For example, at present one of the main contributors to greenhouse is the use of coal for the generation of electricity. Using methane gas would produce the same amount of electricity for much less carbon dioxide production.
Some coal mines generate a lot of methane gas from their coal seams. In the past that gas has been allowed to escape into the atmosphere, so contributing directly to the greenhouse effect.
Therening tea/coffee.
[Dr Bob Hunter is director of the Centre for Human Aspects of Science and Technology at the University of Sydney.]