Tim the Plumber wrote:
Ann Vole wrote:
Wayne Stollings wrote:
oh no! they all look like hockey sticks!
I'll go with the longest graph.
Which "longest" graph would that be? Several extend farther in the past but for the comparison are set to the same scale.
It does not extend into the Roman period thus does not refer to the point of this thread.
Not on this graph but the data for some of them do extend farther back.
The point is that if the climate was warmer than now in the Roman period, ( a safe bet given the Roman growing of vines in York ), then that warming happened without the effect of increased CO2. And the present warming cannot be seen as exectional when compaired to the longer historic view.
Faulty logic exhibiting a lack of understanding of localized and larger climate data. The current heat wave in the northern hemisphere is brutal, but the global average temperature is not that much different. If one were to take the data from the US and made a generalization about the global climate they would be wrong.
If the tree ring data which shows this Roman warm period is good(the data) then the present warm period cannot be automatically atributed to industrial activity.
A big if, but the warming is not automatically treated as anything without supporting data ... except by those such as are sometimes called deniers.
If the tree ring data is unreliable then the origional hockey stick data must be discounted as equally unreliable.
Again faulty logic. The original tree ring data temperature reconstruction has been supported in reconstructions using other types of data. It is this independent verifcation that gives credibility to the reconstruction. This ONE study treating the tree ring data differently is not supported by any other research and unless and until it is will not have sufficient credibility for any real comparison. If it is found to be in correct it will only reflect on the treatment mechanism used to generate the reconstruction and not all of that type of data. This study clearly states it has a different reconstruction than the other studies, which makes it the outlier at this point in time.
There are other temperature data sets which do to variuos degrees show the "hockey stick" sudden warming of the period 1970-2000.
You mean ALL of the instrumental methods of temperature measurement?