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Thursday, October 15, 2009

Sea Level and Climate 

Today is Blog Action Day, so along with thousands of other Bloggers around the world, I am writing a post to highlight this year's issue of climate change. As promised, I have chosen the subject of sea level rise and you might ask, why sea level rise?

My reason for choosing this topic began when considering the arguments relating to climate change, the impact of man-made Carbon Dioxide (CO2) in the atmosphere on global warming and what it means to individuals. It is a fact that humans are genetically programmed for their individual survival; few put the benefit of others over themselves.

Most people are not therefore motivated to do much about global warming unless there is a direct, immeadiate economic benefit to them. Notice the word immeadiate because by its very nature, global warming normally occurs over a much longer timescale than a period likely to impact human lifetimes. Indeed, many people, feafull of the effect on their lifestyle of measures to counter global warming, actively argue against any link between atmospheric Carbon Dioxide levels and climate change. Just this week, "global warming skeptics" have been cock-a-hoop at a report from BBC climate correspondent, Paul Hudson, suggesting that climate models did not forecast a fall in global temperatures experienced over the last decade. Hudson reported Professor Don Easterbrook of Western Washington University, USA, as saying that global temperatures were correlated much more with cyclical oceanic oscillations of warming and cooling than anything man does, arguing that the global cooling from 1945 to 1977 was linked to one of these cold Pacific cycles, and that "the Pacific decadal oscillation cool mode has replaced the warm mode [of 1978 to 1998], virtually assuring us of about 30 years of global cooling.

This argument highlights some of the major issues surrounding the global warming debate, chief of which is probably the extreme complexity of the evironment and the extremely wide level of scientific knowledge needed to model it. It is important to appreciate that scientific models are only a description of a system, they allow us to make predictions and are essentially based on observed data; as more data is obtained, models can be improved. At one time, people believed that the earth was flat and that the sun circled the earth but with more observations scientists were able to improve the planetary model to such a degree that it was possible to land a spaceship on the moon.

One of the most pronounced and observable effects of climate change has been the melting of glaciers and ice sheets around the world. Glacial melting is occurring in Alaska, the Himalayas, the Andes and over the past century, the volume of glacial ice on Africa's Mount Kilimanjaro, has decreased by such a rate that its glaciers will be likely to disappear within the next 10 years. Just today, it has been reported by Professor Peter Wadhams at the University of Cambridge, UK, that data obtained by the 2009 Catlin Arctic Survey supports the view that in 10 years time there will only be a small piece of Arctic ice remaining to the north of Greenland and that within 20 to 30 years, all the Arctic ice will be gone.

We might therefore argue against the evidence for global warming but we cannot deny that the ice is melting! Part of this paradox is explained by a lack of understanding of the physics involved. When heat from the sun falls on ice, the heat melts it but the ice/water mixture remains at 0 Celsius because the energy has been used to melt the ice, not raise its temperature above the melting point. By the way, we have all seen the dramatic pictures of ice sheets falling into the sea and most of us are aware that if we have a glass of water and drop ice into it, the water will cool down, so we should not be surprised if sea temperatures are lowered.

Now so complex is this subject that one statement leads to many more issues deserving discussion; before you know it a small post has turned into a book. The impact of ice melt is profound, not will be profound, is profound. Ice sheets are still the world's largest reservoir of fresh water and this volume of fresh water diluting the sea will have dramatic consequences. Furthermore, you don't have to be a rocket scientist to know that if you drop enough ice into a glass of water it will spill over.

Stefan Rahmstorf, a widely recognized sea level expert, from Germany's Potsdam Institute recently told a climate conference at Oxford University in the UK, " a rise of at least two meters in the world's sea levels is now almost unstoppable, there is no way I can see to stop this rise, even if we have gone to zero (Carbon Dioxide) emissions". Like many natural phenomena, the process of ice melt and sea level rise is something that starts very slowly but then escalates and when it reaches a certain critical point, there is no turning back.

The loss of sea ice at the poles is likely to set in motion a powerful climate feedback mechanism, amplifying and accelerating the consequences of global warming. It could result in flooding that will affect one-quarter of the world's population and cause extreme global weather changes, hurricanes, drought, even maybe unseasonal snow. Will this affect you? It doesn't just depend on whether your one of the 1 in 4 getting wet, 200 million environmental migrants have to go somewhere, unless the rest of the world is prepared to just standby and watch them drown or die from drought. Even your food and energy supplies could be disrupted, so it matters not if you are fortunate enough to live on high ground, you may still find that you have to adjust your lifestyle.

Incidentally, a 2 metre rise in sea level is now reckoned to be a bit on the low side, the eventual rise could be as much as 7 metres and a Tsunami of 4 metres on top of a 2 metre average sea level, would create a wall of water 6 metre higher than wer'e used to paddling in.

I know that few will be motivated to do much unless circumstances force them to react but perhaps it is a good idea to ask "what if" and make a few worst case plans. In one sense, it doesn't really matter what the cause of climate change is, it is clear that the times they are a changing. Besides, as someone commented, "what is so terrible about moving towards a renewable energy economy? And how does the £1.2 trillion a year cost measure up against the cost of maintaining the status quo (wars, the building of weapons, sustaining unpleasant regimes, pollution health matters, etc.)? "

How high's the water mama?

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