[JLS]

I think a huge problem is that just like the airport examples, a well sited station can change if asphalt and building are built around it over the years. That makes the time-series have a trend not due to carbon dioxide or really any change in climate.

[MileHi]

Or if they move the airport 35 miles like they did in Denver. How do you relate the new data to the historical data measured at the old location?