Page - 178 - in Water, Energy, and Environment - A Primer

westerncoastofAustralia,consideredoneofthebestplaces inthe world to study sea levels of the past.’Toquote further from the Gillis article, ‘the paper focuses on awarmperiod in theEarth’s history that preceded the most recent ice age. In that epoch, sometimes called the Eemian, the planetary temperature was similar to levels we may see in coming decades as a result of human emissions, so it is considered a possible indicator of things to come.’ ‘Examiningelevated fossilbeachesandcoral reefsalongmore than a thousand miles of coast, Dr O’Leary’s group confirm something we pretty much already knew. In the warmer world of the Eemian, sea level stabilized for several thousand years at about 10 to 12 feet abovemodern sea level. The interesting part is what happened after that. Dr O’Leary’s Group found what they consider to be compelling evidence that near the endof the Eemian, sea level jumped by another 17 feet or so, to settle at close to 30 feet above themodern level, before beginning to fall as the iceageset in. In an interview,Dr.O’Leary toldmehewas confident that the17 foot jumphappened in less thana thousand years – how much less, he cannot be sure.’ Of course, this group’s findingsmust be subject to critical scrutiny, but ‘if the work does hold up, the implications are profound. The only possible explanation for such a large, rapid jump in sea level is the catastrophic collapse of a polar ice sheet, on either Greenland or Antarctica. Dr. O’Leary is not prepared to say which; figuring that out is thegroup’snextproject.But a17 foot rise in less thana thousandyears, ageologic instant, has tomean that oneorboth ice sheets contain someprofound instability that can be set off by a warmer climate. That, of course, augers poorly for humans. Scientists at Stanford calculated recently that human emissions are causing the climate to changemany times faster than at any point since the dinosaurs died out. We are pushing the climate systemsohard that, if the ice sheetsdohave athresholdofsomekind,westandagoodchanceofexceedingit.’ Water,Energy, andEnvironment–APrimer178