CHANGES IN CLIMATE

Madam, - The recent report from the Environmental Protection Agency is to be welcomed, as it gives voice to a hypothesis that…

Madam, - The recent report from the Environmental Protection Agency is to be welcomed, as it gives voice to a hypothesis that is seldom heard in the media. The authors of the study state that the warming trends observed in Ireland could be attributed to the "'natural oscillations' of the Atlantic weather system" (November 26th). Unfortunately, many individuals will ignore this hypothesis.

Several facts which are not reported widely are of key importance in any scientific study addressing the possible implications of global warming. As a soon-to-graduate Ph.D. candidate in chemistry, I feel it is important to inform the public of some issues which have been made clear in several reports by the UN's Intergovernmental Panel on Climate Change.

Unfortunately, these findings do not predict the cataclysmic destruction of the earth by global warming effects, and therefore do not rate the front page in most media outlets.

First, this panel has determined that the global surface temperature of the earth has increased by about 0.6

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Secondly, there has been no increase in storm frequency or violence in any part of the globe as a result of this warming. People often mistake the increased reporting of storms in far-off parts of the globe for an unusual increase in storm activity. Thirdly, the effects of aerosols and greenhouse gases on the climate are poorly understood. In particular, aerosols can contribute to a cooling effect, but very little is known concerning the mechanisms of this action.

The authors hypothesise that this "indirect effect" of cooling by aerosols could be so large as to mitigate the warming effects of greenhouse gases, but more scientific study needs to be undertaken to determine this.

Lastly, the models used by this panel to predict climate change are based on many factors which the authors themselves label as being poorly understood at best. Therefore, I caution individuals from making too much of predictions based on these models. They are scientifically imprecise at best, and contain wide margins of error.

While I agree with the wisdom of doing what we can to reduce the impact we have on our planet, I suggest that individuals clamouring for the withdrawal of the combustion engine consider instead recycling and other, local efforts. We have only begun to unravel the science behind climate change, and to make demands and predictions based on limited data is emotional and nonscientific. We are not hovering on the brink of destruction as the result of greenhouse gases, and it will likely take another 30 years for a clearer picture of our climate and the forces at work within it to emerge.

In the meantime, let us hope that the emotional rhetoric is toned down by the pursuit of self-education concerning the science of climate change. - Yours, etc.,

ALLISON PHAYRE,

Ph.D. Candidate,

Arizona State University,

Department of Chemistry &

Biochemistry,

Box 1604,

Tempe, AZ 85287-1604,

USA