Your team is losing the game with five minutes to play, and no hope in sight. How do you win?
The graph above was the IPCC view of the world in 1990. Nothing scary there, and that simply needed more research to get sorted out properly.
So their careful studies killed off that nasty MWP, and started to build the hockey stick using temperature proxies. Temperature proxy studies commonly use tree rings to measure past temperatures. This method worked really well until the trees apparently went on strike in 1960. Briffa in green, Jones in red, and Mann in blue.
The MWP had disappeared, but they still had a problem. They had to do something about that inexplicable “decline” in temperatures after 1960.
One of the three temperature reconstructions was based entirely on a particular set of tree-ring data that shows a strong correlation with temperature from the 19th century through to the mid-20th century, but does not show a realistic trend of temperature after 1960. This is well known and is called the ‘decline’ or ‘divergence’. The use of the term ‘hiding the decline’ was in an email written in haste. CRU has not sought to hide the decline. Indeed, CRU has published a number of articles that both illustrate, and discuss the implications of, this recent tree-ring decline, including the article that is listed in the legend of the WMO Statement figure. It is because of this trend in these tree-ring data that we know does not represent temperature change that I only show this series up to 1960 in the WMO Statement.
Those wicked trees just started misbehaving after 1960. After doing a fine job for a thousand years, the trees apparently just said enough is enough – “we are not going to cooperate any more.”
At that point, the only sensible approach was to throw away the tree’s deviant data. In order to compensate for the tree’s bad behaviour, Mike had to come up with a “nature trick.” So they shot the trees in the head, and turned the post 1960 temperatures over to the reliable folks who do the thermometer adjustments. And there you have it – the hockey stick!
In less than 20 years, the IPCC rewrote most of the climate history of the modern world, going from this :
Sometimes, all you need to win is a new hockey stick!
Now, aren’t you glad that engineers don’t throw away inconvenient data when they build bridges?