You do, actually. We only have non-thermometer data for the preceding 11300 years, so it is important to establish that the thermometer data correlates with the non-thermometer data, so as to fully understand the trends in the data. Imagine if MMTS stations greatly over/under estimate temperature values relative to the non-thermometer methodologies. That would mean the preceding 11300 year baseline for the trend would be a misrepresentation.
This correlation of data acquisition appears to have been done until the conversion of recording stations to MMTS stations. The correlation stop, at that point, and we are now entirely dependent on thermometer data. Coincidentally this is is also the 'hockeystick blade' time frame.
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You do, actually. We only have non-thermometer data for the preceding 11300 years, so it is important to establish that the thermometer data correlates with the non-thermometer data, so as to fully understand the trends in the data. Imagine if MMTS stations greatly over/under estimate temperature values relative to the non-thermometer methodologies. That would mean the preceding 11300 year baseline for the trend would be a misrepresentation.
This correlation of data acquisition appears to have been done until the conversion of recording stations to MMTS stations. The correlation stop, at that point, and we are now entirely dependent on thermometer data. Coincidentally this is is also the 'hockeystick blade' time frame.