Holocene Arctic Climate Variability: Past, Present and Future

Ray Bradley, from the Climate System Research Center in UMASS Amherst, reviews how changes in Earth’s orbital relationship to the sun, and consequent changes in insolation, produced warming in the early Holocene akin to what we can expect with projected anthropogenic warming of 2-degrees centigrade. Bradley explains how the dominant feature of the temperature record over that time span has been a slow decline, followed by a recent sharp rise. Warm temperatures of the early Holocene occurred when the Earth was closest to the sun during summer. 10,000 years later, we are closest during January. As a consequence, he notes, wintertime polar temperatures demonstrate an increase 2-3 times greater than mean global annual temperature increase. During summer, polar amplification is “merely” double the global average. Reappearance of blue mussels in Svalbard (last seen in the early Holocene), are evidence that it may indeed be an analog for further changes yet in store.