Posted by: Hendra Siry | 10 June, 2008

Rising sea levels threaten cities

Sea-level rise caused by global warning is already tracking above the global average along Australia’s northern and western coastline, leading scientists have warned.Scenarios outlined in more than 40 submissions to a recent federal inquiry into environmental impacts of climate change on coastal communities included that the risk of storm surges and tidal damage to four of Australia’s coastal capitals Darwin, Brisbane, Sydney and Melbourne had increased at least fourfold.

And Cairns ”is particularly at risk” from flooding with potential for a disaster similar to that which hit New Orleans, unless Australia radically stepped up its lagging pace on climate change adaptation.

Another scenario showed Sydney’s extreme or maximum sea levels used to calculate flood and erosion risks from storms and high tides had risen 10cm over the past 40 years, and were expected to rise a further 10cm by 2020.

And on the NSW Central Coast, the rapid beach erosion in some towns had forced councils to order residents to dismantle structures in their backyards to reduce pressure on seaward slopes.

The scenarios warned of devastating impacts to coastal towns, infrastructure such as roads, sewage and water supply systems, tourism and coastal ecosystems as Australia’s coastline becomes increasingly vulnerable to the effects of global warming.

University of Sydney coastal geographer Emeritus Professor Bruce Thom said, ”This is scary stuff.”

He told the inquiry Australia lacked a national coastal policy, was allowing dangerous ”hodge-podge” coastal development and had no federal science agency coordinating coastal research or mapping the economic cost of climate change on coastal communities.

”We will reach ‘tipping points’ in each and every coastal community around our coast as sea level continues to rise. Each tipping point needs to be assessed in relation to the nation’s ability to pay. When will barrages be needed at Port Philip or Botany Bay? When will the very low third runway at Sydney Airport need to be elevated?”

Professor Thom said Gosford was already experiencing more drain flooding by seawater at high tides, causing corrosion of infrastructure.

Many coastal towns like Lakes Entrance in East Gippsland were becoming vulnerable to ”the Venice effect” with increased frequency of flooding during seasonal high tides.

”So much is at stake in terms of vulnerable property assets, water security, endangered habitats, tourism … The cost of inaction now will escalate in the future unless we seek ways to manage and plan for the adverse impacts of climate change,” he said.

The Bureau of Meteorology told the inquiry global climate models suggested mean sea-level rises on the east coast of Australia could exceed global averages. The bureau said it was crucial for Australia to maintain a ”strong climate modelling program” to map long-terms trends and adaptation.

University of Wollongong coastal geographer Professor Colin Woodroffe said Australia’s coast was likely to be ”especially impacted” by climate change because ”such a large proportion of the Australian population lives along, or visits the coast”.

Tide gauges indicated sea levels were rising ”at an accelerating rate, with several places experiencing rates that are above the global average”.

Cairns was particularly at risk from storm surge flooding and it was important to develop adaptation guidelines ”to avoid disasters of the sort that have befallen New Orleans”.

Scientists from the Antarctic Climate Cooperative Research Centre said research on sea-level rise was ”in its infancy and being done in a relatively fragmented way around Australia”.

They warned adaptation responses were ”often poorly informed, inadequate or even dangerous”.

Federal Labor MP Craig Thomson, whose Central Coast electorate of Dobell includes Gosford and Terrigal, said heavy rain plus wave energy impact at Norah Head had ”placed a number of homes in the unenviable position of currently having no backyards plus the potential of losing their homes to the sea”.

The demographics of Dobell made disaster planning problematic, with a large commuter population of more than 30,000 people travelling to Sydney or Newcastle on a daily basis.

BY ROSSLYN BEEBY SCIENCE AND ENVIRONMENT REPORTER

Source: Canberra Times


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