 So you know in this effort to discredit climate science in the lead up to the 2009 Copenhagen Summit where you know various emails including emails that were mine or were written to me were stolen and then combed through to try to find words and phrases that if you took them out of context could sound you know a little questionable could be used to try to make it sound like climate scientists were engaged in something inappropriate were hiding something and so that's what climate change deniers did they combed through thousands of emails looking for even just one little short phrase that they could use to try to attack climate scientists and one phrase that they seized upon was an email to me and some other scientists from my colleague Phil Jones of the University of East Anglia what the critics also tried to do is to take two different phrases from the same email that appear at opposite ends of a very long sentence and splice them together so you actually heard people there are people out there claiming that the email talked about using a trick to hide the decline using Mike's trick to hide the decline the email doesn't say anything of the sort that hide the decline is referring to something else later in the sentence what Phil Jones was talking about was that one particular climate reconstruction that was shown in his comparison that had been performed by Keith Briffa and colleagues with the University of East Anglia they had used density the density of the rings of trees so in addition to the width of the individual truings the density of the wood that makes up the trees also appears to respond to the climate so with have with a warmer summers we tend to get trees which denser especially at the end of the grand season kind of the late wood that's put down by the trees at the end of the grand season the density there is linked to summer temperature even more strongly than the width of the ring width so you can use tree ring growth thicknesses tell you something about climate but it turns out that if you look at the density of the wood that grows in any particular year that also tells you something about temperature and so they had performed a reconstruction of temperatures using exclusively these tree ring density measurements and for various reasons that have been explored for you know now nearly two decades these particular measurements track temperatures very well until about 1960 and then they began to diverge and what truing divergence is is a separation in the trends of the tree data and the temperature data in recent decades so if you go back to the early part of the 20th century there's quite a good correspondence between the tree data and the temperatures so that warmer summers tend to coincide with wider rings or with denser wood in those rings and colder summers with less dense wood or thinner rings the thermometer measurements tell us very clearly that the globe warmed substantially since then but the tree ring data stopped the tree ring densities that they used stop sort of reflecting that warming so the divergence problem is something that affects some truings often it's as misconstrued as if it affects all truings what it is is that for some truings the changes in recent decades have gone down while the temperatures recorded at the same locations have gone up whereas you go back to previous decades the truings have responded quite closely to the temperatures when the summers are warmer than normal the trees have tended to grow more than normal and our view has been that this is the cause of it is likely to be something fairly unique to the 20th century because in order to have this common effect on many different trees across northern hemisphere you need something you know large-scale and and affecting you know many regions in one in one time period and therefore some anthropogenic pollution related influence or maybe some climate warming related influence could be part of the explanation so the paper recently by Stein and Hoibers that suggested that changes in the sunlight reaching the trees could explain the divergence and they're backed up by looking back at the earlier record and identifying a change when volcanic eruptions occur which also put aerosol and dust into the atmosphere and which can also affect the amount of sunlight reached in the trees and that seemed to be consistent with the divergent with the locations where the divergence is strongest in recent decades. Before that email ever was written they had published a year earlier a paper in the journal Nature talking about this problem it was hardly something that was hidden or nefarious they were well aware of this problem and they stated very clearly in that paper in 1999 1998 that because of this problem you should not use the post 1960 data to depict temperature changes and so what Phil Jones was talking about that email was he was hiding all he meant was not misleading the readers of this report by showing them this very misleading post 1960 tree ring density data because they wrongly convey what was actually happening with temperatures and we have thermometer measurements that tell us what actually happened with temperatures so he was literally saying for this simple graphic that's supposed to convey to this lay audience what we know about temperatures over the past thousand years let's not show this bad data that will confuse them and mislead them but somehow that was parlayed once again into something nefarious something inappropriate by you know very cynical bad-faith actors who were you know using this misdirection and confusion really as a distraction to make sure that there were no meaningful negotiations and dealing with climate change at the upcoming Copenhagen summit in 2009 but that's sort of what you have when you're left without a legitimate argument for your case which is where we have what we have in the case of climate change denial today all you've got to turn to apparently is in Uendo and obfuscation and misdirection and this was just another example of that