Jo Nova finds the Medieval Warm Period

From Jo Nova a look at how the MWP looks when other data is used, not just a few trees in Yamal.

These maps and graphs make it clear just how brazen the fraud of the Hockey Stick is.

World Map of temperatures and studies showing warming

Click to enlarge

It’s clear that the world was warmer during medieval times. Marked on the map are study after study (all peer-reviewed) from all around the world with results of temperatures from the medieval time compared to today. These use ice cores, stalagmites, sediments, and isotopes. They agree with 6,144 boreholes around the world which found that temperatures were about 0.5°C warmer world wide.

Huang et al Boreholes graph of world temperatures

Bishop Pachuri of the IPCC and his wind powered staff

What follows is a sordid tale of a graph that overthrew decades of work, conveniently fitted the climate models, and was lauded triumphantly in glossy publication after publication. But then it was crushed when an unpaid analyst stripped it bare. It had been published in the highest most prestigious journal, Nature, but no one had checked it before or after it was spread far and wide. Not Nature, not the IPCC, not any other climate researcher.

In 1995 everyone agreed the world was warmer in medieval times, but CO2 was low then and that didn’t fit with climate models. In 1998, suddenly Michael Mann ignored the other studies and produced a graph that scared the world — tree rings show the “1990’s was the hottest decade for a thousand years”. Now temperatures exactly “fit” the rise in carbon! The IPCC used the graph all over their 2001 report. Government departments copied it. The media told everyone.

But Steven McIntyre was suspicious. He wanted to verify it, yet Mann repeatedly refused to provide his data or methods — normally a basic requirement of any scientific paper. It took legal action to get the information that should have been freely available. Within days McIntyre showed that the statistics were so flawed that you could feed in random data, and still make the same hockey stick shape nine times out of ten. Mann had left out some tree rings he said he’d included. If someone did a graph like this in a stock prospectus, they would be jailed.

GRAPH: Mann's Hockey stick graph wiped out the midieval warm period with statistical trickery.

Astonishingly, Nature refused to publish the correction. It was published elsewhere, and backed up by the Wegman Report, an independent committee of statistical experts.

GRAPH: Briffa's reconstruction was affected by one freak tree.

In 2009 McIntyre did it again with Briffa’s Hockey Stick. After asking and waiting three years for the data, it took just three days to expose it too as baseless. For nine years Briffa had concealed that he only had 12 trees in the sample from 1990 onwards, and that one freakish tree virtually transformed the graph. When McIntyre graphed another 34 trees from the same region of Russia, there was no Hockey Stick.

The sharp upward swing of the graph was due to one single tree in Yamal.

Skeptical scientists have literally hundreds of samples. Unskeptical scientists have one tree in Yamal, and a few flawed bristlecones…

It was an audacious fraud.

Climate models don’t know why it was warmer 800 years ago.

The models are wrong.

The so-called “expert review” is meaningless. The IPCC say 2,500 experts review their reports, but those same “experts” made the baseless Hockey Stick graph their logo in 2001.

Craig Loehle used 18 proxies to graph the last 2000 years.

Craig Loehle used 18 other proxies. Temperatures were higher 1000 years ago, & cooler 300 years ago. We started warming long before cars and powerstations were invented. There’s little correlation with CO2 levels.

Sources: Loehle 2007, Haung and Pollack 1997, See for all the other peer reviewed studies to go with every orange dot on the map.  McIntyre & McKitrick 2003 and 2005, and update, Mann et al 1998, Briffa 2006, read McIntyre at, see “ClimateGate”, and  Monckton “What Hockey Stick” (Science and Public Policy Institute paper)

This is Page 8 & 9 The Skeptics Handbook II. 20 page PDF

I know a similar graph went up a couple of days ago around the web. The skeptics Handbook II was published on Friday Nov 20.

ACKNOWLEDGEMENTS: Thanks to Craig Idso of for his fabulous collation of research and his Medieval Warming Project which is an excellent resource, try the animated map!  A big thank you to John N for his work in helping to create the map.