"Global" warming is undoubtedly occurring over much of this earth. The IPCC summary of WG!'s 2007 Fourth Assessment Report established that. However, we must be cautious with our interpretation. It puts forth many estimations and "likely" scenarios, which, incidentally, have been degraded from their previous Assessment Report as a result of more credible climatic data. Future scientific procedures could reduce them more.

The NOAA contributed significantly to this IPCC study. Their responses to questions have indicated that much is vague about atmospheric dynamics during past millenniums, even up to a few decades ago. Therefore, is the current global warming an on-going phenomenon or merely a blip in a climatic variation? Considering that the earth is about 4 billion years old and untold such variations have occurred, certainly more will in the future. Current scientific data hasn't established whether we are in a variation now nor shown conclusively that we are entering a historic, centuries-long trend.

It is shortsighted to dwell on possible cataclysmic effects of global warming. The IPCC report is based primarily on recent scientific climatic considerations. Therefore, its prognostications are probably valid for the short term but not as a forecast for continuous heating of the entire earth.

Ed Westervelt

Nevada City