WHAT RISING SEA LEVELS MEAN

As we all try and get a sense of rising sea levels and what they mean, consider below the commentary of recognized experts.  According to the PBS program “NOW” (December 15, 2008) a top UN official predicts that by the middle of this century, the world should expect six million people per year to be displaced by increasingly severe storms and floods caused by climate change. And in its landmark assessment of climate change published in 2007, the Intergovernmental Panel on Climate Change (IPPC) concludes that sea level rise would probably range between 28 and 43 cm (11 and 17 inches) over the century, although 59 cm (23”) is a possibility. They have been widely criticised for predicting such an increase, however the most recent data, presented in Copenhagen (March 10-12, 2009), suggests a far higher figure with dramatic implications for many island nations and coastal regions.

The current rate is about 3 mm per year. Additionally, David Vaughan in the British Antarctic Survey tells the BBC that "...whatever happens in this century can only start from present conditions and present rates of sea level rise, and that constrains the rise that can occur this century. However, if you're looking further ahead than 2100 - and many governments are, including the Netherlands and the UK which are thinking about infrastructure that would last more than 100 years - then that second century still looks quite scary.”

In the United States, the National Wildlife Federation conducted a study which showed that by 2100 the Pacific Northwest coast could have a significant sea level rise of between 50 -142 cm (20 - 56 inches). Among the most vulnerable habitats are estuarine beaches, which provides vital spawning areas for forage fish, including surf smelt and sand lance, which in turn provide food for birds, marine mammals, salmon, and other fish and wildlife. More than 2/3 of beaches in the Tacoma, Washington area are predicted to be lost by 2100, and that loss would become irreversible some time in the second half of this century.

Elsewhere in the world there is major concern. Once a threshold of warming is crossed there would be a catastrophic sea level rise of at least 20ft, (6 meters) drowning the centre of London and displacing millions in Britain alone. Two international teams reported in the journal Science (March 2006) that Arctic summers by 2100 may be as warm or warmer than they were nearly 130,000 years ago, when sea levels eventually rose up to 20ft (6 meters) higher than today. Such a rise had been thought to be at least 1,000 years away. Scientists predict that should greenhouse gases increase over this century be between 3 and 5 degrees Celsius, that this would make the Arctic completely free of sea ice by 2100.

The Maldives, a chain of 1200 island and coral atolls in the Indian Ocean with a population of 300,000, are likely to disappear under the waves if the current pace of climate change continues. The first island disappeared in 2006. The obliteration of Lohachara Island, home to 10,000 people in India's Bay of Bengal, marked the moment when one of the most apocalyptic predictions of environmentalists and climate scientists came true. (See Dec. 24 2006 news item here.)

Sea-level rise, however, does not happen in isolation with other climatic events. The food chain is severely altered. Each change triggers other problems which affect each other. How would the world cope with millions of people seeking refuge? We’re all, eventually, affected somehow even if we live far away from the oceans. Major concern is being shown around the world, especially in low lying countries such as Bangladesh and The Netherlands. Other nations around the world are taking note: Australia Green Party spokesperson, Christine Milne comments claims that: “ . . . our own scientists have come out saying the IPCC is likely to underestimate its sea level rise because it hasn't taken into account the latest science on the glacial melt, particularly in the Antarctic." Professor David Vaughan of the British Antarctic Survey admits that estimates of future rises remain alarmingly hazy. But “with around 17 million people living near the coast in the UK, this is something we cannot afford to ignore,” he says. “One financial disaster zone would be the Thames Estuary, in which 1.25 million people live, 1.5 million commute and there are assets worth up to £100 billion," Vaughan explains.

Effects of sea level rise

            The IPCC report also notes that based on the projected increases, current and future climate change will especially impact coastal systems. Such impacts could include increased coastal erosion, higher storm-surge flooding, changes in surface water quality and groundwater characteristics, increased loss of property and coastal habitats, increased flood risk and potential loss of life, impacts on agriculture and aquaculture through decline in soil and water quality, and loss of tourism recreation and transportation functions. Partly because the estimates by the IPCC took no account of meltwater from Greenland's glaciers, the rise in sea levels this century could be twice or three times as great as it forecast. 

Statistical data on the human impact of sea level rise is scarce. A study in the April, 2007 issue of Environment and Urbanization reports that world-wide 634 million people live in coastal areas within 30 feet (9.1m) of sea level. The study also reports that about 2/3 of the world's cities with over five million people are located in these low-lying coastal areas. The IPCC report of 2007 estimated that accelerated melting of the Himalayan ice caps and the resulting rise in sea levels would likely increase the severity of flooding in the short-term during the rainy season and greatly magnify the impact of tidal storm surges during the cyclone season. A sea-level rise of just 40 cm (15.7 inches) in the Bay of Bengal would put 11 percent of the country's coastal land underwater, creating 7 to 10 million climate refugees.

Note: It is estimated that Antarctica (which holds 90% of the world's ice), if fully melted, would contribute more than 60 meters (197 feet) of sea level rise, and Greenland would contribute more than 7 meters (23 feet). Fortunately we don’t need to be anxious about this risk for maybe a thousand years in the case of Antarctica although the Antarctic Peninsula, particularly the West coast of the Peninsula, is warming at a rate 2 or 3 times faster than the global average.

Alan Burns – March 14, 2009

This world map allows visitors to check the results of sea-levels rises between 1 and 14 meters anywhere in the world.

March 8 2009 report in Guardian: Rising sea levels pose a far bigger eco threat than previously thought.  read

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