Thursday, October 30, 2008

Nourish my beach please!

From Sydney Morning Herald

Beaches will wash away by Ben Cubby, Environment Reporter
October 29, 2008

It's a cruel dilemma: Sydney will get hotter but you can't escape to the beach. Bondi, Manly and Coogee, which are backed by heavy duty sea walls, are expected to escape the worst of rising sea levels but only for a while. By 2050, most of Sydney's 150-odd major beaches will need thousands of tonnes of extra sand delivered by truck to survive in anything like their current condition, experts believe.

The projected sea level rise of up to 40 centimetres in the next four decades, revealed yesterday by the NSW Government, will change the city's coastline. Even the runways of Sydney Airport may need to be reinforced, according to Professor Andy Short from the University of Sydney's coastal studies unit.

Relatively narrow beaches such as Manly and Cronulla have little room to retreat and governments should consider funding beach-widening programs now, Professor Short said. A coalition of local councils along the NSW coast is awaiting more detailed projections from the State Government so they can issue advice to coastal land owners and perhaps modify planning approval laws to take climate change into account.

Blogger Note: Beach nourishment ( including replenishment and restoration) is a very expensive and in many cases the only feasible proposition, which many of the small islands will not be able to afford. Many small islands depend upon tourism, in particular beach tourism, as a central economic pillar. Therefore direct impacts on beaches will directly hurt island economies and impair their ability to respond and adapt to such changes. The Sea Level Rise Foundation aims to create a network and promote the exchange of techniques and approaches to beach restoration, and thus avoid the costly mistakes associated with such exercises. Whilst beach nourishment may appear straight forward and many will be tempted to get heavy earth moving machines moving sand around at enormous cost. Before one does so, it important to note that one may encourage further beach loss and erosion if one ignores expert input and impact assessments.  Furthermore, beach nourishment should not be considered as an alternative to proper beach management and protection,and hotel developers should be aware that proper beach management and protection will increase the long term resilience of beaches and reduce nourishment costs.

Further reading:

NOAA Coastal Services Centre has come out with a Beach Nourishment Guide here.

Tuesday, October 28, 2008

Turtles under threat from Climate Change

tn_turtle Whilst humans have driven populations of  marine turtles to the brink of extinction through endless activities such as direct hunting, consumption of its eggs, use of  fishing gear, beachfront tourism development, and pollution, more is yet to come.Climate change and its impacts on nesting beaches and forage areas will further affect turtle populations around the planet. Such is the conclusion of a report by Oceana which shows how sea level rise, change sea surface temperatures,currents and ocean acidification as a result of climate change will affect turtle populations around the world. Once beaches are eroded as a result of sea level rise and other extreme events, significant nesting habitats will be lost. Increased in temperatures would favour more female turtles as sex is determined by temperature in turtles. Alteration in ocean currents may also affect migration patterns and ocean acidification will impact on food sources.

Download report.

Monday, October 27, 2008

Sea surface temp a leading climate issue

From Siapan Tribune

Main Article from Siapan Tribune

By Kristi Eaton
Reporter

APIA, Samoa-Although most people correlate climate change with rising sea levels, the first big effect of climate change to the Pacific will be a rise in sea surface temperature, affecting storms, droughts and coral ecosystems, a marine researcher said at the Pacific Climate Change Roundtable being held here.
Paul Anderson, a marine resource analyst, said projections show air temperature could rise 2 degrees Celsius to 6.4 degrees Celsius by 2100.
Anderson works for the Secretariat of the Pacific Regional Environment Programme, a regional organization based in Apia that is charged with protecting and managing the region's environment and natural resources.
“This warming is causing sea-level rise that will gradually inundate coastal areas and increase beach erosion and flooding from coastal storms, changes in precipitation patterns, increased risk of droughts and floods, threats to biodiversity, and a number of potential challenges for public health,” he said.
Sea levels could rise by .35 to 1 meter in the next century, depending on the arctic glacial stability, Anderson said. This will cause more frequent and more intense storms, one of the first visible effects of climate change.
Coral reefs are also being affected by the changing climate. Seventy-five percent of the world's reefs are found in the Indo-Pacific region, but the coral cover has been cut in half since 1980 from 42 percent to 22 percent.
“If modeling projections are even close to valid, corals and reefs will be severely tested by the end of the century, possibly sooner,” Anderson said.
Reefs will become bleached when they get too hot and the algae move out, he said. Also, they can be damaged by natural events like hurricanes, cyclones and tsunamis. Dissolving carbon dioxide in the seawater will decrease pH levels, slowing coral growth rates.
All of these issues add up to less coral to break a storm surge, so tropical cyclones will have a larger effect on the coast and the communities, Anderson said.

Blogger Comment:

I could not agree more, in fact the western Indian Ocean suffered mass coral bleaching in 1998 causing some reefs in the Seychelles to experience 95% mortality. The reefs are growing back but there has been repeated, luckily smaller, bleaching events in the last 10 years. CORDIO is a major initiative funded by Sweden and other to study the impact of sea surface temperature on coral reefs and associated marine life the Western Indian Ocean. Unfortunately, coral bleaching is also linked to the damage that can be caused by sea level rise. When reefs are damaged, research by the author and others have shown that more wave energy with the potential to hit the coastline will further aggravate erosion. When sea-level rise is added to the mix, you can guess the result.

Further Reading:

Sheppard C., Dixon D, Gourlay, M., Sheppard, A., Payet R.A. 2005c Coral mortality increases wave energy reaching shores protected by reef flats: Examples from the Seychelles, Journal of Estuarine, Coastal and Shelf Science 64: 223-234.