Read here. Map source. Modern climate alarmists, such as Joe Romm, Michael Mann, Jeff Masters, Al Gore and Kevin Trenberth, commonly deny or lie about significant climate change that took place over the last 5,000 years. Reflecting on their denial of the overwhelming empirical evidence, if they were to admit to the reality of past climate change then that would be a tacit approval that abrupt climate change is natural and does not require high atmospheric levels of CO2. Adding to their woes of gross misrepresentation of past climate history, comes another new study that confirms the reality of past abrupt climate change, further denigrating the position of all past climate change deniers.
Larsen et al. performed multiple analysis of sediment cores of an Iceland glacial lake. The analysis clearly documents the robust climate change during the periods of the Dark Ages,the Medieval Warming and the Little Ice Age. The empirical evidence points to the extreme warmth of Iceland's climate during the MWP and the extreme cold of the LIA.
"A suite of environmental proxies in annually laminated sediments from Hvítárvatn, a proglacial lake in the central highlands of Iceland, are used to reconstruct regional climate variability and glacial activity for the past 3000 years...Varve thickness is controlled by the rate of glacial erosion and efficiency of subglacial discharge from the adjacent Langjökull ice cap...ice-cap expansion is punctuated by notable periods of rapid ice cap growth and/or landscape instability at ca 1000 BC, 600 BC, 550 AD and 1250 AD. The largest perturbation began ca 1250 AD, signaling the onset of the Little Ice Age and the termination of three centuries of relative warmth during Medieval times.Consistent deposition of ice-rafted debris in Hvítárvatn is restricted to the last 250 years, demonstrating that Langjökull only advanced into Hvítárvatn during the coldest centuries of the Little Ice Age." [Darren J. Larsena, Gifford H. Millera, Áslaug Geirsdóttirb, Thorvaldur Thordarsonc 2011: Quaternary Science Reviews]