Sea levels rising higher and faster
Article on SMH.com.au
SEA levels will rise higher and faster than the United Nations predicted just four years ago, a major international study has found.
The new data suggests that, on average, the seas will rise by up to 1.6 metres by the year 2100 - a finding that has serious implications for Australian governments grappling with coastal planning.
The Arctic Monitoring and Assessment Program, based in Norway, found that the Greenland ice sheet is melting four times as fast as it was a decade ago.
‘‘The past six years have been the warmest period ever recorded in the Arctic,’’ the authors of the report said in a statement. ‘‘In the future, global sea level is projected to rise by 0.9 metres to 1.6 metres by 2100 and the loss of ice from Arctic glaciers, ice caps and the Greenland ice sheet will make a substantial contribution.’‘
Each centimetre of sea-level rise roughly translates to one metre of beach erosion, meaning that the coastline can be expected to move 160 metres further inland.
The most recent assessment from the Intergovernmental Panel on Climate Change, released in 2007, put the projected rise at 59 centimetres by 2100. It acknowledged the views of many researchers that this figure was conservative.
In the past few years, sea levels have risen an average of about 3 millimetres a year, with 40 per cent of this attributed to melting Arctic glaciers, ice caps and the Greenland ice sheet.
The rate is expected to accelerate as the world warms this century and the process will be compounded as more ice cover is lost. White ice fields reflect sunlight away from the Earth’s surface, whereas the darker oceans absorb more of the sun’s heat, amplifying global warming.
Australia’s Department of Climate Change and Energy Efficiency said its 2009 report into the effects had taken into account the possibility of high sea-level rises.
“There is growing consensus in the science community that sea-level rise at the upper end of the IPCC estimates is plausible by the end of this century, and that a rise of more than 1.0 metre and as high as 1.5 metres cannot be ruled out,” its report said.
The report found that as many as 247,000 residential buildings with a value of $63 billion may be at risk of inundation from a sea-level rise scenario of 1.1 metres by 2100.
The NSW Office of Environment and Heritage said it would monitor scientific developments and provide new advice to coastal councils in 2014, when the UN is expected to finalise its next assessment.