Climate change insight - sea levels fall as well as rise

A common misconception reported in the popular media about climate change science involves predictions of ice sheets melting with commensurate rising sea levels across coastlines. In many reports the impression  given is that the effects are somehow uniform across the globe with dire effects. This perception and selective presentation of information is incorrect. There are  several other factors and influences which occur with melting ice sheets. For example, the actual physics of large ice sheets involve gravitational effects - any large mass on Earth whether a continent or a massive ice field exerts a significant gravitational pull on water surrounding it, thus drawing the liquid towards its perimeter. When the ice melts the water is released and the sea level falls. This has been known since 1888 when physicist, Robert Woodward published his findings and was utilised again in 1976 in work by William Farrell and James Clark when calculating potential impacts from the melt of the great northern ice sheets. A second factor is the weight of ice sheets on the earth's crust - the crust is actually pushed down by the ice sheets in the Northern and Southern polar and sub arctic regions and with the current melting, the crust rebounds and rises. Hudson Bay is currently rising a centimetre a year and has been doing so since the last ice age.

There are also more complex physics impacts to consider - the volume of water and ice actually influences the Earth's rotation. The planet's balance is altered if a large ice sheet melts hence the distribution of water is altered. The melting of Greenland would shift the axis of rotation approx half a kilometre towards the ex-ice sheet. These effects mean that the levels of sea rise would be quite different across continents and countries - Scotland could see a sea fall of more than 3 metres whilst South America could see a sea rise of close to 10 metres.