Is sea level rise going down or up?

A couple of scientific papers recently (see my Del-icio-us bookmarks) has led to some climate sceptics to point to the fact that sea level may indeed be overstated, a fallacy or perhaps not linked to global climate change.

The first paper by Fletcher and company used various scientific techniques to study the role of carbon dioxide in the atmosphere of the planet approximately 200 million years ago, a time when the islands that we know today, even the Seychelles, did not exist. His results are interesting from several perspectives; most relevant is the conclusion that during intense greenhouse warming, cold events leading to the formation of glaciers could happen. This combined with other evidence shows that the sea level might actually go down by 25-40 metres during such an event.The obvious interpretation by some sceptics is that sea level may actually not rise but go down.

The second paper by Bornemann and others, found out that large ice sheets existed over 90 million years ago, despite the fact that the planet was much warmer than it is today. During that period others have argued that crocodiles roamed the Arctic region, and temperatures in the western tropical Atlantic Ocean were 37 degrees Celsius. These findings seem to question our arguments that the ice poles were ice-free during the past warm periods of the planet.

These arguments are linked to the fact that with the formation of ice on land, sea levels will fall and with the subsequent melting of this ice the sea level will rise again. Naturally the outcomes of warming and cooling are much more complex than this and there is much more to learn. It is estimated that if all of the Antarctic ice were to melt it would contribute to about 60 metres, melting of Greenland ice will contribute about 7 metres, and other glaciers about 0.5 metres (see Wikipedia).

Of course, many ‘overzealous’ sceptics say "Aha ! then sea level rise will not happen or it may not be as dramatic as some paint it out to be". In my view these two papers highlight 3 important points which is of significance to small islands and other areas that would be affected by sea-level rise:

1. The evidence today that both Antarctica and Greenland ice is melting is fact, supported by a huge number of scientific papers, video evidence and reports. One therefore cannot rule out sea level rise in the present and near future, and many scientists agree that ‘the current phenomenon is happening at a much different time-scale and context than what happen in prehistorical times’. On the 3^rd Jan 08, I reviewed a paper which indicated that research from prehistoric coral reefs showed a rapid raise in sea level rise, following by subsequent decreases in sea level.

2. As I have argued before the rate of sea level rise is still a very imprecise science due to the lack of long-term historical data and also observing system constraints. However, the fact that the sea level is rising cannot be disputed.

3. A very small rise is sea level, no more than 1 to 2 metres, will affect most islands and most low-lying parts of the world. This is what we should focus our energies on, because communities will be displaced, traditions will be lost and economies will be affected if we do not avoid this 1-2 metre rise. The research into our prehistory shows us that the variation in sea levels within a warm period can involve several cycles of rising and decreasing. Are we on the rise or on the decrease in sea level level? The present scientific evidence points to a rise, hence we need to be concerned.

In conclusion these changes described by those important research into our past, indicates the unpredictability of the climate if we continue to with business as usual and supercharge the atmosphere with greenhouse gases. Remember a temporary sea level rise is still sea level rise and would cause the same damage as a permanent sea level rise would. Perhaps one adaptation option would be to ‘temporarily’ evacuate the islanders, and then relocate then back at the advent of the cold snap !!! Perhaps there is hope after all..who knows.

Evidence is available and has been presented by the IPCC 2007 reports which clearly indicates that we are supercharging our atmosphere with carbon dioxide arising from human activities. Think about it - in those days we had crocodiles and a number of other species– today we have human lives which we all value so much – not just our fancy car or ORV.