Wednesday, September 30, 2009

Two metre sea level rise unstoppable-experts

From Reuters

By Gerard Wynn
OXFORD, England, Sept 29 (Reuters) - A rise of at least two metres in the world's sea levels is now almost unstoppable, experts told a climate conference at Oxford University on Tuesday.
"The crux of the sea level issue is that it starts very slowly but once it gets going it is practically unstoppable," said Stefan Rahmstorf, a scientist at Germany's Potsdam Institute and a widely recognised sea level expert.
"There is no way I can see to stop this rise, even if we have gone to zero emissions."
Rahmstorf said the best outcome was that after temperatures stabilised, sea levels would only rise at a steady rate "for centuries to come", and not accelerate.
Most scientists expect at least 2 degrees Celsius warming as a result of man-made greenhouse gas emissions, and probably more. The world warmed 0.7-0.8 degrees last century.
Rahmstorf estimated that if the world limited warming to 1.5 degrees then it would still see two metres sea level rise over centuries, which would see some island nations disappear.
His best guess was a one metre rise this century, assuming three degrees warming, and up to five metres over the next 300 years.
"There is nothing we can do to stop this unless we manage to cool the planet. That would require extracting the carbon dioxide from the atmosphere. There is no way of doing this on the sufficient scale known today," he said.
Scientists say that ice melt acquires a momentum of its own - for example warming the air as less ice reflects less heat, warming the local area.
"Once the ice is on the move, it's like a tipping point which reinforces itself," said Wageningen University's Pier Vellinga, citing various research.
"Even if you reduce all the emissions in the world once this has started it may be unstoppable. I conclude that beyond 2 degrees global average temperature rise the probability of the Greenland ice sheet disintegrating is 50 percent or more."
"(That) will result in about 7 metres sea level rise, and the time frame is about 300-1,000 years."
Delegates from about 190 nations are meeting in Bangkok to try to speed up U.N.-led negotiations to replace the Kyoto Protocol with a tougher climate pact. [ID:nLS243569]
Speakers in Oxford used history to back up their arguments on rising seas. Three million years ago the planet was 2-3 degrees warmer and the sea 25-35 metres higher, and 122,000 years ago 2 degrees warmer and 10 metres higher, they said.
"What we now see in Greenland, Antarctica could be a temporary phenomena but it could also be the start of what we saw 122,000 years ago," said Vellinga.
Sea levels have risen about 20 centimetres in the past century and that effect was accelerating, speakers said.
That rise was adding to storms such as that in the Philippines [ID:nSP127545], although that single event couldn't be attributed to climate change, said Rahmstorf.
"Of course the flooding from a given storm event would be less severe if we hadn't added those extra centimetres."
About 40 million people worldwide live in flood plains, said Southampton University's Robert Nicholls. That is 0.6 percent of the global population and 5 percent of global wealth, because of valuable assets such as airports and power plants.
He was confident that coastal protection could hugely reduce lost land and assets. The cost of that speakers put at anywhere from 50 billion euros ($72.85 billion) a year by 2020 to up to $215 billion a year by 2100.

Monday, September 28, 2009

Mangroves battle rising tides in South-East Asia

Friday September 25th

Across South East Asia coastal communities are already battling rising tides – one of the first signs of climate change. In Indonesia and Vietnam coastal development and climate change have resulted in a dangerous combination of sinking land and rising sea levels.

Launching tonight on BBC World News, the latest Earth Report programme, ‘Heads Above Water’, explores how the Vietnamese government is fighting back. Over the last quarter century, large areas of coastal mangroves have been cleared for commercial shrimp farms. Now those shrimp farms themselves are under threat from climate-related flooding. Semarang, Java's fifth largest city, is slowly sinking beneath the sea – its port, railway yard and many homes now under water for six months a year.

Vietnam too is vulnerable. A one-metre increase in sea level could destroy much food production in the Mekong Delta – the nation’s breadbasket - and force millions to flee.

BBC World News broadcasts ‘Heads Above Water’, the fourth programme in the new ‘Earth Report’ series at the following times:
Friday September 25th at 19.30;
Saturday September 26th at 04.30;
Monday September 28th at 12.30 (Asia Pacific only),
Tuesday September 29th at 15.30, and
Wednesday September 30th at 01.30 (except Asia Pacific, South Asia and Middle East) (all times UK time zone)

BBC World News broadcast times vary around the world. For details of transmissions in your region, check the BBC World News website.

For the Vietnamese government, regenerating the mangroves has become the first line of defence against sea level rise. The country’s 3,000 kilometre coastline is low lying, heavily populated – leaving the region’s people, food production and economy extremely exposed.

Vietnam is the world’s second largest exporter of rice and the Mekong Delta in the south of the country is Vietnam’s ricebasket but the World Bank estimates the delta is more vulnerable to sea level rise than anywhere else in the world. A worst case scenario included in a recent Vietnamese government report shows that one-third of the delta - where 17 million people live and nearly half the country’s rice is grown - could be submerged if sea levels rise by three feet over the next few decades.

The Vietnamese government has set a target to plant 250,000 hectares of mangroves along the entire coastline, and the government consider the mangrove regeneration work so important they have appointed local wardens to guard them from logging. Mr. Tung worked as a farmer most of his life, but since 2001 he has patrolled the mangrove forests, in the Soc Trang area of the Mekong Delta. Earth Report goes on patrol with Mr Tung and with Vietnamese forestry experts to find out if the country’s green sea defences are working to keep heads above water.

Earth Report ‘Heads Above Water’ has been produced with the generous support of Mangroves for the Future. To find out more about Heads Above Water, visit the Earth Report website. To view a high definition clip from the programme, visit the tve’s YouTube channel.