By JR on Thursday, February 11, 2016
Wot! No hockeystick?
When Mike Mann's proxy-based "hockeystick" picture of the earth's climate history over the last 1,000 years came out, it was greeted with wild acclaim by Warmists. It even featured at the front of an IPCC report or two. It showed an unchanging temperature until the late 20th century, when the temperature suddenly shot up -- exactly the Warmist dream. It was however soon shown as a botch and the IPCC no longer mentions it.
But Mann and some others still find hockeysticks wherever they look so I thought a careful proxy study of the last 1,000 years would be useful. The one below is from 2011 but is notable for its careful assembly of all available proxies. Following the abstract, I present one of their graphs, which shows most clearly what they found. You will see that our climate history is one of ups and downs and we are just at an end of an up
Northern Hemisphere temperature patterns in the last 12 centuries
F. C. Ljungqvist et al.
We analyze the spatio-temporal patterns of temperature variability over Northern Hemisphere land areas, on centennial time-scales, for the last 12 centuries using an unprecedentedly large network of temperature-sensitive proxy records.
Geographically widespread positive temperature anomalies are observed from the 9th to 11th centuries, similar in extent and magnitude to the 20th century mean.
A dominance of widespread negative anomalies is observed from the 16th to 18th centuries. Though we find the amplitude and spatial extent of the 20th century warming is within the range of natural variability over the last 12 centuries, we also find that the rate of warming from the 19th to the 20th century is unprecedented. [More warming in the 19th century!]
The positive Northern Hemisphere temperature change from the 19th to the 20th century is clearly the largest between any two consecutive centuries in the past 12 centuries. [Reflecting recovery from the Little Ice Age]
Clim. Past Discuss., 7, 3349–3397, 2011