On Jan 24, 5:26*am, (Doug Miller) wrote:
In article , Luigi Zanasi wrote:

On Jan 23, 10:38=A0am, Dave Balderstone
wrote:
snip
One reporting station being used for everything north of 65 degrees in
Canada's north? A station in Hawaii being used to project data 1200
miles north?

Well, if there's only one station north of 65, this should result in
showing less warming. The temperatures in Canada's north have been
clearly and unequivocally warming.

You miss the point, and thus draw a completely incorrect conclusion:
temperatures at latitudes of, say, 70 degrees are generally quite a bit lower
than at latitudes of, say, 40 degrees. Removing temperature stations at high
latitudes necessarily skews the average temperature of the remaining stations
upward, even if their individual temperatures don't change at all.

For a concrete (although admittedly simplistic) example, suppose we're going
to determine the average temperature of North America by averaging the
temperatures today at Point Barrow AK; Whitehorse YK; Duluth MN; Houston TX;
San Diego CA; and Miami FL. Now, for tomorrow's reading, eliminate Point
Barrow and Whitehorse from that list. How do you suppose tomorrow's average
will compare to today's?

Granted that the year (or day, or whatever period) after the northern
stations are eliminated will show a jump in temperature.

However, in subsequent years, assuming that the north is warming up
faster than the south, the measured increase will be less than the
real one. That is the point I was making, maybe not as well as I
should.

Luigi