The Physics (Score 2, Informative)

By no means am I an expert in the field, but I do have a firm head on my shoulders, and am confused by the lack of any "discussion" section in the BBC report. So here is a part of mine. Although it is common to say that the top of a continuous body of water is all at the same elevation (a fact surveyers use extensevly to reduce costs), that statement is wrong. The tops of water bodies follow an equipotential surface. This means that each top point will have the same potential energy. In small surfaces, such as lakes, the difference between the equipotential surface and the equi-elevation surface is nearly zero, so it is not taken into account. In larger bodies, such as the entirety of north America, or even the world, spherical coordinates are not as useful. Geoids have been used for many years to approximate the equipotential surface on the earth (search NAD27) but even they do not capture the peculiarities that occur with local lead outcroppings or other local density peculairities on the earth. Another coomonly understood fact is that water is most dense at 34 degrees farenheight. A not commonly understood fact is that the global ocean circulation patterns are very slow. Put these three ideas together and one can figure out that it is not the oceans that have been lowering, but that there is more cold water near the polar ice caps then there was before becasue of the increased rate of ice melt. This effect has increased the density of the polar ice cap region and decreased the elevation of local equipotential curve. The decrase in absolute elevation is true, but the equipoential elevation has been rising. If I am wrong on any of this, please correct me. Have a good day.