By steven d keeler | Mar 02, 2014
Are we overlooking potential abrupt climate shifts ?
Most of the studies and debates on potential climate change, along with its ecological and economic impacts, have focused on the ongoing buildup of industrial greenhouse gases in the atmosphere and a gradual increase in global temperatures. This line of thinking, however, fails to consider another potentially disruptive climate scenario. It ignores recent and rapidly advancing evidence that Earth’s climate repeatedly has shifted abruptly and dramatically in the past, and is capable of doing so in the future.
We will illustrate our case with reference to a debate currently taking place in the circle of Quaternary climate scientists. The climate history of the past few million years is characterized by repeated transitions between 'cold' ( glacial ) and 'warm' ( interglacial ) climates. The first modern men were hunting mammoth during the last glacial era. This era culminated around 20,000 years ago and then declined rapidly. By 9,000 years ago climate was close to the modern one. The current interglacial, called the Holocene, should now be coming to an end, when compared to previous interglacials, yet clearly it is not. The debate is about when to expect the next glacial inception, setting aside human activities, which may well have perturbed natural cycles.
On the other hand, the broad duration of an interglacial may be de-termined by the phasing of astronomical parameters and the history of insolation, rather than the instantaneous forcing strength at inception.
.... thus, the first major reactivation of the bipolar seesaw would probably constitute an indication that the transition to a glacial state had already taken place.
authors note : bipolar seesaw - the differences in sea ice cover between the arctic and antarctic regions.
Southern Hemisphere Sea Ice Area reached a minimum of 2.447 Million Sq km on February 23th, 2014, which exceeded the prior 2nd highest minimum of 2.423 Million Sq km that occurred on February 22nd, 2013. The highest recorded Southern Hemisphere Sea Ice Area minimum remains 2.473 Million Sq km, which occurred on March 1st, 2003.