Viewpoint

CO₂ Emission Controls -- What's the Cost?

C.R.de Freitas

Important changes are occurring in the global warming debate. Increasing numbers of atmospheric scientists are speaking out against the now-established impression of greenhouse gas-induced climate change. They argue that the popular perception of the dangers of impending global warming, now so widely accepted that it is taught in every school and university, is a product of exaggerated claims. This view, they contend, is so tainted with half-truths and oversimplifications that it is producing bad policy and the risk of economically disruptive legislation.

Just recently the Ministry for the Environment ruled that the Electricity Corporation be granted an air discharge consent for its proposed Stratford station only on condition that it plant a forest to absorb the carbon that would be emitted from the 400 megawatt gas-fired station. This is an important precedent, one that may set the tone of a national policy on greenhouse gas emissions.

New Zealand is the first country to formally recognize "carbon offsets" as a way of meeting its commitment to the Climate Convention. This approach appears to be favoured over the more direct method of carbon taxes or tradable emission certificates, the relative merits of which has been the subject of much debate over past years. But, until now, there has been no compulsion to restrict or offset emissions, for two important reasons.

The first is that it is clear that the economic implications, both direct and indirect, are immense. For example, to absorb the emissions form the Stratford station, the board of inquiry heard that over 4,000ha of trees would need to be planted each year, at an annual cost of about $2.5 million. The second reason is that there is growing scientific backing for the view that costly restrictions are not necessary.

Earlier this year, Richard Lindzen, an internationally renowned atmospheric scientist, visited New Zealand. Based on his research work, Professor Lindzen challenges the apocalyptic view of the world influenced by an enhanced greenhouse effect. Critics argue that this represents an extreme, minority scientific opinion and goes against the consensus view of scientific beliefs.

This is the environmentally and politically correct position, but it fails to recognise that important changes have occurred in the global warming debate. The most important is that there are no longer any grounds for claiming that there is a consensus of opinion among the scientific community. Professor Lindzen is but one of a great number of eminent atmospheric scientists who are speaking out against the now-established popular impression of greenhouse gas-induced climate change and impending danger to the environment.

It is very tempting to make predictions of climate change. Use of global climate models (GCMs) is the best method currently available for this, but despite the mathematical complexity of these models they do not adequately account for the complex workings of the atmosphere. Moreover, there are large discrepancies between predictions from different GCMs. The established truth is that there are no reliable predictions of future climate or climate change. It is surprising therefore that the results of these models have been so credulously accepted.

Concepts of a fixed or constant climate can be misleading. As it is a dynamic system, global climate has always been both highly variable and constantly changing. Normal year-to-year variations in climate are 10 to 100 times greater than the changes we have been persuaded to expect from increased concentrations of greenhouse gases in the atmosphere.

It is true that the concentration of carbon dioxide in the atmosphere is increasing, as it has in past. But there is well founded scepticism about the adequacy of this information alone as a basis for taking strong action.

Greenhouse gases are largely naturally occurring gases, essential for life on earth. Despite this, there is a tendency to equate the greenhouse gases with air pollution or damage to the environment. Clearly, few would want to argue that air pollutants that are caused by carbon-based fuel emissions are not a problem, or that finite fossil fuels resources should be squandered, but these are not the issue. The artificial CFC gases aside, the main greenhouse gases are gases that have always had a role in global climate processes, with concentrations in the past rising above and falling below present levels.

The carbon dioxide content of the atmosphere has varied widely in the period between the last glaciation and the start of the industrial revolution, indicating that there are more than human-induced effects at work. About 100 million years ago the Earth's mean temperature was very similar to today's, even though the atmosphere then contained about eight times the present concentration of carbon dioxide.

Part of the problem is the tendency to focus on the negative aspects of climate. Pessimism sells. In fact, most evidence from GCMs suggests that increases in greenhouse gases will give rise to a wetter and warmer climate in most places. By convention, warm periods in Earth's past are referred to as periods of climatic improvement, since plant growth is more often limited by temperatures that are too low rather than too high. High concentrations of atmospheric carbon dioxide will increase the rate of photosynthesis and result in higher yields. For agriculture generally, the worst-case prognosis is for changed rather than reduced opportunities.

Doom and gloom predictions of threats to the coastal zone are another favourite theme. The much-publicised pronouncements from the Villach world climate conference in Austria during 1985 warned of a possible 1.4 metre rise in global sea level by 2050. Subsequently, more rigorous analysis led to "likely" estimates being revised steadily downwards.

The current "expected" rise in sea level rise is about 30 centimetres by 2050. But sea level changes of this size during El Nino periods are not uncommon, and sensitivity of coastal systems seems to be reasonably low. Given that enhanced greenhouse warming will intensify the hydrologic cycle and increase precipitation, it can just as easily be shown that a less than 1% increase in precipitation over the vast Antarctic continent would result in a 50-centimetre fall in sea level due to increased storage of water in the form of continental ice.

Other Factors

Just as greenhouse gas concentrations change, so do many other factors. Recent research, for example, shows that rapidly increasing concentrations of sulphate aerosols in the atmosphere will lead to cooling, both directly and indirectly. Moreover, there are other natural processes at work that dwarf the subtle processes of radiative forcing associated with greenhouse gases that cause the atmosphere to warm or to cool, such as, for example, the worldwide pattern of cooling in recent years caused by the 1991 eruption of the Philippine volcano Mount Pinatubo.

An intergovernmental Panel of Climate Change (IPCC) sponsored by the United Nations has been laying the groundwork for international conventions on global warming, and is often quoted as "the" authority on such matters. It claims that severe and damaging global warming is inevitable. An increasing number of scientists do not now accept the IPCC conclusions and call attention to the fact that IPCC reports are based on faith in existing global climate models.

In response to this, IPCC projections of warming trends have been scaled down in the last few years. And in view of current debates and criticisms, IPCC's ongoing claim to scientific consensus does nothing to enhance its credibility.

The IPCC urges governments to implement national policies to combat global warming as a safety measure. It is considered politically and environmentally correct to support policy decisions that are portrayed as overly cautious so as to err on the side of safety.

Such policy follows what is known as the Precautionary Principle. Roughly translated it means that, in the absence of knowledge about certain safety, do nothing to disturb the natural order of things. If economic burdens associated with environmental action were trivial, the policy decisions made in accordance with the Precautionary Principle would be easy. But the costs of carbon taxes and offsets are enormous.

Implementation of national and international emission reduction strategies such as that suggested by the Framework Convention on Climate Change will collectively have immense social and economic effects in New Zealand and across the globe. The impact is likely to be far greater than any change caused by global warming.

There is no doubt that concern for the environment will continue to be a strong force for change -- as it should be, given the great potential for human action to damage natural systems. But instead of emotional environmentalism, we need environmental management based upon sound science and a sensible link between environmental and economic policies.

Climatologist Dr Chris de Freitas is Associate Professor and Head of the Division of Science and Technology at the University of Auckland's Tamaki Campus.