Yes glenc I am aware of the satellites reading northern warming and of course that cannot be disputed but the issue of warming always uses world average temp. Like as in - the world has warmed by ...... The ignoring of UHI remains a valid point as to input data not reflecting reality.
The northern tendency to show more warming than elsewhere has to do with the axis tilt and precession.
This link gets into some of that:
http://www.livescience.com/forcesofn...arth_tilt.html
And this link has quite a bit of Earth climate history:
http://www.clearlight.com/~mhieb/WVF.../ice_ages.html