The ends of an era

摘要

If geologists were to construct 'top ten' lists of the advances of the century, the relatively recent discovery that the Earth has switched repeatedly and abruptly between cold and warm climates over the course of ice-age cycles would no doubt feature prominently. Yet, despite the decade of research devoted to characterizing this so-called 'millennial-scale' climate variability, there are still primary questions about the origin of such abrupt changes and, therefore, equal uncertainties in predicting how climate might behave in the future. These questions surfaced last month at an American Geophysical Union conference, where a few scientists challenged established dogma centred on the North Atlantic by suggesting that the tropical Pacific may have been involved — a fitting proposal in a year when El Nino took the blame for a variety of human woes.