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Smaller glaciers, not giant ice caps, tipped to push sea levels up

By David Hewitt - 12 Jan 2011 10:50:1 GMT
Smaller glaciers, not giant ice caps, tipped to push sea levels up

That climate scientists looking into rising sea levels are currently directing their research at the massive ice caps of the Arctic and the Antarctic is hardly surprising. After all, it is estimated the West Antarctica region alone – a mass of land the size of Greenland and home to natural behemoths such as the Pink Island Glacier – is responsible for ten per cent of the global sea level rises seen over the past few years.

However, the findings of a new study suggest that it will be the 'melt off' from smaller mountain glaciers and inland ice caps, rather than from the world's biggest ice shelves, that will drive sea level increases over the coming decades. This new research, which was carried out the University of British Columbia, saw a team of climatologists develop a simulation capable of modelling anticipated volume loss and melt off from some 120,000 sites around the world between now and 120,000. Unlike previously-developed models, this time around the scientists made an effort to achieve detailed projections per region instead of merely focusing on wider trends.

"There is a lot of focus on the large ice sheets but very few global scale studies quantifying how much melt to expect from these smaller glaciers that make up about 40 percent of the entire sea-level rise that we observe right now," lead researcher Valentin Radic, from the Department of Earth and Ocean Sciences at UBC, explained, writing up the findings in the academic journal Nature Geoscience.

Interestingly, despite the fact that smaller mountain glaciers are known to contain less than one per cent of all the Earth's water that is bound in glacier ice, the model shows that they will be responsible for a disproportionally large proportion of sea level rises. More specifically, it is anticipated that landlocked glaciers in the likes of New Zealand, Western Canada, the Western United States and the Caucus region of Eurasia will lose more than 50 per cent of their current ice volume as a result of climate change before the century is over.

Indeed, working with predictions for future temperature increases and glacier melt rates generated by ten separate global climate models – all of which are also used by the Intergovernmental Panel of Climate Change - the team have concluded that these smaller ice sources will contribute around 12 centimetres to world sea-level increases over the remainder of the century, with this likely to have catastrophic consequences for numerous natural habitats as well as for hundreds of thousands of people.

Furthermore, as the Vancouver-based scientists themselves acknowledge, these latest predictions do not take into account the likely effects of 'calving', whereby large ice sheets break up to form glaciers, thereby leaving large volumes of ice more-susceptible to melting. It is hoped to figure this factor into future work, with a more-localised approach again set to be used to give a more-detailed picture of the potential shape of things to come.

But if this latest study is cause for concern, then a separate paper, also released this week by Canadian scientists, is positively alarming. Working on a 'best case scenario' of global carbon emissions reaching a zero level by the end of the century, the simulation designed by experts at the Canadian Centre for Climate Modelling and Analysis and the University of Calgary, has concluded that recent rises in greenhouse gas emissions will nevertheless cause unstoppable effects to the global climate for the next 1,000 years. Alarmingly, the model predicts that the next millennium will see around 30 per cent of North Africa turned to desert, a five per cent increase in ocean warming leading to a collapse of the Western Antarctic, and a related five metre rise in sea levels.

Models can, of course, be revised or even disproven over time, as has certainly been the case over the past few years. However, even if either of these scientific predictions are only partially accurate, the world's seas and oceans look set to be subjected to dramatic and potentially catastrophic change over the coming decades and centuries.