Dr. Busalacchi begins by summarizing what he describes as "what most scientists agree to be true about change in the Earth's climate," noting that the globe warmed by about 0.4 to 0.8°C over the past century, which statement he supports with numerous references to a diverse array of evidence consistent with the demise of the Little Ice Age that had ruled the world for several prior centuries.  From that point on, however, Busalacchi is careful to acknowledge the existence of two radically different views about the cause of this welcome climatic amelioration.

The first of these views is that the increase in temperature that ushered in the Modern Warm Period was caused by the concomitant increase in atmospheric greenhouse gases that occurred "as a result of human activities."  Although many people are confident of the correctness of this assessment, Busalacchi rightly states that "uncertainty remains because there is a level of natural variability inherent in the climate system on time scales of decades to centuries that can be difficult to interpret with precision," which statement pretty much describes the other view of the subject, i.e., that the Little Ice Age to Modern Warm Period transition was nothing more nor less than the most recent expression of a millennial-scale oscillation of climate (most likely driven by a millennial-scale oscillation of solar activity), that has been repeatedly observed as far back in time as science has been able to see.

Continuing, Busalacchi notes that believers in CO2-induced global warming claim that the northern polar region of the planet is much like the proverbial canary in a coal mine, being the place where the effects of the predicted increase in temperature "will be felt first and with the greatest magnitude."  With respect to this concept, he cites the recent breakup of the Ward Hunt Ice Shelf on the north coast of Canada's Ellesmere Island (the northernmost land mass of North America), noting that climate alarmists "believe this change can be attributed to global warming."  He then reports, however, that "other scientists have been more cautious, noting that many of the changes being seen in the Arctic could have more to do with long-term world climate patterns than with the release of carbon dioxide and other greenhouse gases."

Busalacchi also mentions a number of other Arctic phenomena that climate alarmists cite as evidence of CO2-induced warming over the past few decades.  However, he is careful to note that "the conclusion that the cause is greenhouse warming is still open to debate," stating that "many of the records are either short, of uncertain quality, or provide limited spatial coverage."  In addition, he says that "some of the changes being experienced at high latitudes are believed to be reflections of changes in wintertime wind patterns rather than a direct consequence of global warming per se."  He also references "the rapid warming of the Northern Hemisphere during the first part of the 20th century," well before the majority of anthropogenic CO2 emissions occurred, along with the subsequent cooling of the globe, all of which phenomena are clearly indicative of significant non-greenhouse forcing of climate.

So where does this brief review of the real-world science of global warming leave us?  The view of Senator John McCain, who presided over the hearing, is that "there is broad scientific consensus that global warming is occurring, that human activity is causing it, and that ? no excuse for inaction on this issue is acceptable," with his and Senator Joseph Lieberman's proposal for action being mandatory caps on anthropogenic CO2 emissions with federal oversight.

Dr. Busalacchi, however, proposes something far different, in light of the paucity of evidence for what Senator McCain vainly attempts to portray as fact.  Noting that the economic and environmental implications of the issue are huge, and that "understanding climate and whether it is changing, and why, is one of the most crucial questions facing humankind in the twenty-first century," Busalacchi says "it is imperative for the nation to continue directing resources toward better observing, modeling, and understanding of what form future changes in climate and climate variability may take, the potential positive and negative impacts of these changes on humans and ecosystems, and how society can best mitigate or adapt to these changes."

Clearly, until these several scientific objectives have been substantially achieved, there is no room for even discussing the strident compulsory measures Senators McCain and Lieberman are attempting to foist upon the nation.