Waterworld scenario sinks

Another indication of the depth of our collective ignorance about the activity in the Earth’s oceans is a report by a group of eminent statisticians who happened to be looking at aspects of the IPCC’s work, as part of an argument about a thing called the Hockey Stick graph. The argument over the hockey stick itself need not detain us - that is a whole other article - but the report is immensely valuable as one of the few independent reviews of climate research I have seen by a group with no obvious axe to grind.

The group’s report (PDF 1.41MB) prints a summary of a 2002 paper by Carl Wunsch, a professor of Physical Oceanography at Massachusetts Institute of Technology in the US.

Wunsch says that until recently scientists assumed that ocean circulation was stable mainly because they were unable to make systematic measurements of conditions at varying depths. Now technology has improved.

“With the advent of modern electronics, obtaining time series of oceanographic data became easier. After years of literature and data on the subject it became clear that the ocean is actually quite turbulent under the surface and that few, if any elements of ocean circulation are truly steady.”

In other words there is a lot happening under the ocean surface, and that any attempt to predict ocean heights a century out are probably just stabs in the dark. Scientists may have a better idea in 20 years or so.

Scientists reluctant to let this image of flooded cities die a natural death have pointed to what they see as potential “tipping points” in the melting of various chunks of the ice caps, so that they will soon all melt at once. Cynics may mutter “how theatrical”. But basically there is no evidence that this fast-track melting has ever occurred, despite much greater swings in temperature in Earth’s history.

This suggestion amounts to speculation - until we see evidence of it happening. Various other scientists appeared after the IPCC released its report in what seemed to be a competition to find more sea level increases, and resurrect the waterworld scenario. Regrettably for those very learned scientists the NTC figures would seem to indicate that the oceans are taking a breather from earlier increases - at least as far anyone knows, but then no-one knows a lot.

While we wait around another 20 years or so for reliable data the best any of the officials who worry over town planning regulations or building codes can do is check shore lines in their areas with the worst case IPCC projections in mind, and perhaps add something for storm surges.

Any changes required could be done when the building stock is renewed but in any case flooding from the sea, as opposed to flooding from rivers or storm water, does not seem to be a problem - or at least not for the moment.

Various Government committees have been examining the problem of flooding of late, following the events of New Orleans, which managed to get flooded entirely without the help of climate change. A report on the Insurance Council of Australia web site (www.insurancecouncil.com.au - submission entitled COAG and Natural Disasters in Australia) notes that about 6.5 per cent of Australian houses are subject to flooding from river water once every 100 years, but there is no data concerning flooding by sea water.

As climate change is supposed to mean reductions in rainfall and rivers drying up, it follows that homes should flood less often. In other words the future may bring less flooding not more, although the effect will vary from district to district. All this means that if you have a house by the beach then by all means keep it - your great, great grandchildren may want to use it.