Magazine article IPA Review

The Greenhouse Panic

Magazine article IPA Review

The Greenhouse Panic

Article excerpt

IT seems to be accepted by many that 'the greenhouse effect' necessitates major reductions in greenhouse gas emissions, particularly carbon dioxide, lest dire climatic changes occur to all our detriment. The alarmist prejudices of insecure people have been boosted by those who have something to gain from widespread public concern.

Typical of recent media comment on the issue is the assertion: "But some scientists are increasingly worried that Greenhouse gases could wreak havoc with the earth's climate in future generations, creating huge floods and droughts from global warming."(1) As usual there is no indication of which scientists have these calamitous opinions; they certainly do not originate from the international consortium of climatologists(2) who are continually collating results from recent greenhouse-climate change studies and updating informed opinion.

Nevertheless such unchallenged hyperbole has induced something akin to panic reaction from policy-makers, both national and international. In response, our Government has adopted a national interim target of a return to 1988 greenhouse gas emissions by the year 2000 and to a level of 20 per cent below 1988 emissions by the year 2005.(3) Also, together with well over 100 national signatories, it has ratified the Framework Convention on Climate Change (FCCC), opened for signature at the 1992 Earth Summit in Rio de Janeiro. This has as its aim the stabilization of greenhouse gas concentrations in the atmosphere. Both the national target and the international aim are, to say the least, highly questionable.

But why do we need to reduce greenhouse gas emissions? A rational consideration of this question involves a sequence of four assumptions:

* that the scientific theory linking greenhouse gases with climate change is valid, and that global warming and other climate changes will be induced by higher gas concentrations;

* that any such climate change is necessarily detrimental to our well-being;

* that realistically we can achieve a sufficient reduction in greenhouse gas emissions to effect a stabilization of gas concentrations in the atmosphere and thus limit any climate change that would otherwise occur;

* that the total cost to society of such a reduction is less than the cost of adapting to the climate change.

How valid are each of these assumptions?

THE THEORY: Greenhouse scientific theory is well founded,(4) despite the criticisms of sceptics and iconoclasts; but many uncertainties still exist.

While human activity has caused no significant direct increase of the major greenhouse gas, water vapour, there can be no doubt that other such gases are increasing. Measurements made at many sites throughout the world make this evident. The more important of these remaining greenhouse gases are carbon dioxide, methane and nitrous oxide. Fossil-fuel burning is the main reason for the increase of carbon dioxide, and agricultural practices play a major role in the increase of methane and nitrous oxide. Thus energy and food requirements for increases in would population, together with the voracious demands of the existing population, make it inevitable that these gases will continue to accumulate during the foreseeable future. The rate at which this will occur is a current concern -- as is whether we can do anything about it.

Although recent and continuing scientific progress has occurred on several fronts, the timing, magnitude and geographical distribution of climate change due to higher gas levels can be estimated only within quite wide error limits and with limited detail. Many important processes are recognized by climate scientists as being inadequately treated in their models; notable difficulties include the roles of clouds and ocean currents. While obviously the most sensible and careful attempts are being made to effect improvements, there remain some misgivings associated with the way in which these models represent the real atmosphere, and hence with the simulation of any but the broadest aspects of climate in a world with higher greenhouse gas levels. …

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