Interesting thought GM, and sort-of logical, but I only go half way with you.
When we are shown world maps with the amount of temp anomoly as coloured areas, there is always a lot of red in the northern hemi. The south has little or none and even some green/yellow. Makes me believe that the temp increases measured are MAINLY microclimate on a grand scale. Does that make sense? I do not put it down to global warming but a bloody great heat island. They are very different. Let's face it, it is the land based thermometers in the US that provide the bulk of the scary data.
I still don't buy temperature rises in the south and sea level may be excess water from the north. I reckon we are doin OK in the south.
