[RJL]

150 years of data... hmmmm

Yes, why 150 years? Was it warm, medium or cool in 1860?

One of the warmers' favorite starting points for their warming trend graphs is the 1970s since that was the end of 30 years of cooling, so their warming trend graphs have that hockey stick look about them.

On the other hand, if they start their warming trend graphs in 1934 the graph ends in 2009 at almost exactly where it started in 1934.

It's much harder to sell $Trillions in new taxes and government control over every aspect of the people's lives when the graph doesn't show a lick of warming.

[neverdem]

Yes, why 150 years?

Although they have some recorded temperatures going back to 1790s from some places, not many existed before the 1860s. You have to rely on proxy data from tree rings, ice cores, sediment, etc., before that.

Chapter 1 Historical Overview of Climate Change ScienceInspired by the paper Suggestions on a Uniform System of Meteorological Observations (Buys-Ballot, 1872), the International Meteorological Organization (IMO) was formed in 1873. Its successor, the World Meteorological Organization (WMO), still works to promote and exchange standardised meteorological observations. Yet even with uniform observations, there are still four major obstacles to turning instrumental observations into accurate global time series: (1) access to the data in usable form; (2) quality control to remove or edit erroneous data points; (3) homogeneity assessments and adjustments where necessary to ensure the fi delity of the data; and (4) area-averaging in the presence of substantial gaps.