Pak, D.K., Lea, D.W. and Kennett, J.P. 2012. Millennial scale changes in sea surface temperature and ocean circulation in the northeast Pacific, 10-60 kyr BP. Paleoceanography 27: 10.1029/2011PA002238.
In answer to the question of how unusual was 20th-century global warming, climate alarmists typically respond with the word unprecedented! But is that really so?
We know that 20th-century global warming represents the recovery of the world from the global chill of the Little Ice Age, which had been preceded by the Medieval Warm Period, which in turn had come about as a result of the warming that followed the Dark Ages Cold Period, which had been preceded by the Roman Warm Period; and so has Earth’s climate periodically shifted – from cold to warm, and from warm to cold – all the way back through the entire Holocene, as a result of some oscillating forcing factor that alternately warmed and cooled the planet on a millennial timescale. And we know that each of the between-period transitions was of approximately the same absolute magnitude. But what was the situation prior to the Holocene? (more…)