SocialismToday           Socialist Party magazine

Socialism Today 86 - September 2004

Acid rain OK?

AN OPEN UNIVERSITY research team has recently claimed that acid rain could reduce the output of one of the greenhouse gases – methane – that gives rise to global warming. Acid rain is caused by emissions of sulphur dioxide, typically released by burning coal in power stations. The sulphates in acid rain destroy forests and kill fish and other aquatic species.

Dr Vincent Gaudi and his colleagues from the Open University studied the effects of introducing sulphates, at the concentrations found in acid rain, into wetland environments, such as marshes and peat bogs, in Britain, Sweden and the USA. The results showed that methane emissions were reduced by between 30-40%, which is important because methane is one of the gases in the environment that causes global warming. The report of the research in the Proceedings of the National Academy of Sciences in the US asserts that, as a result of acid rain, outputs of methane could be reduced in time to pre-industrial levels.

Methane producing microbes, known for short as MAs, are present in all global wetlands and contribute to global warming. However, there is another group of microbes present in wetlands known for short as SRBs, whose activity is increased by higher levels of sulphates in the environment. According to the theory put forward, when SRBs are stimulated by high sulphate concentrations they take food from the MAs, which as a result are less active, leading to a fall in their methane output.

There are countervailing tendencies at work also, because global warming itself tends to increase MA activity and therefore methane output. But using computer models designed by NASA, the US Space Agency, the authors conclude that the net effect will still be to reduce the greenhouse effect.

This research shows the complex nature of the eco-system and the need to consider it and its interactions as a whole. Does it, though, show a way forward to tackle the problem of global warming? To answer this question it is first necessary to get confirmation that the results presented are generally applicable. The authors of the article, for example, only considered a limited geographical area. There needs to be further research to test that there were no special factors at work in the countries they studied which could limit the global relevance of their findings.

Even if the theory is confirmed, the question of scale need to be considered. Although methane as a result of microbe activity may be reduced by 30-40%, emissions not due to this microbe account for the majority of world methane output. Because of this, the researchers are claiming that methane from all sources will be reduced only by 15% in 2030. But this chemical, although a powerful greenhouse gas, only accounts for 22% of the greenhouse effect, because there is much less of it produced than the main global warming culprit, carbon dioxide. The net effect would therefore be an amelioration of just 3.3% in the greenhouse effect.

Although estimates vary about the required reduction of the greenhouse effect to achieve environmental sustainability, they start at 50% and many environmental activists think that the cuts need to be much higher. When seen in this perspective, the claim of Dr Gaudi (quoted by the BBC) that acid rain is offsetting climate warming quite dramatically is not borne out.

For a very small reduction of one environmental threat, that only scratches the surface of the problem of global warming, there would be a continuation of the damage caused by acid rain, one which capitalist governments, after coming under enormous pressure, have very belatedly started to tackle. Blair’s government, which is increasingly falling behind its commitments to reduce UK greenhouse emissions, may be tempted to present this as a justifiable trade-off, but it is actually no answer at all to the environmental threats looming over us.

Pete Dickenson


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