The Long Baseline

The worrying thing about the most recent climate science is that change seems to be occurring faster than the computer models had predicted. This was not a possibility often entertained by the professional skeptics, who have long insisted that their adversaries in the climate debate were harping on worst-case scenarios in order to incite alarm. In fact, predictions from the IPCC and the various science academies around the world are beginning to seem conservative, even timid when compared to real-world observations.

I should hasten to say that I, at least, do not see skepticism as a bad thing. To the contrary, it is undoubtedly necessary for good science. Moreover, I sincerely hope and pray for all our sakes that the skeptics are right and that we have not pulled the hinges off earth's climate system and ushered ourselves out of the Holocene -- the relatively hospitable epoch that gave rise to civilization.

But, judging from the news, I fear we may have.

The latest issue of Science, the preeminent scientific journal in America, is devoted to ice, our dwindling cryosphere -- ironically, the very stuff that has told us much, if not most, of what we know about the climate of Earth's deep past. It has given us what the editors of Science call the "long baseline" against which to compare our current situation.

The comparison should give us pause, since, as the editors observe, "At no time in at least the past 10 million years has the atmospheric concentration of CO2 exceeded the present value of 380 [parts per million]." They continue:

The Holocene, over its 10,000-year life, has provided us with a comparatively stable period. Now we are changing an important parameter. Evidence presented in two papers, a News story, and two Perspectives in this issue demonstrates an accelerating decay of ice sheets in Greenland and Antarctica. Given the concurrent rapid recent rise in CO2 concentration, history suggests that we should expect other changes. ... Nothing in the record suggests that an "equilibrium" climate model is the right standard of comparison. We are in the midst of a highly kinetic system, and in the past, dramatic climate changes have taken place in only a few decades. Our comfort in the Holocene may have heightened our sense of security, but the expectation that change is unlikely is not a reasonable position.

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