Underwater deserts’ expanding
NEW YORK: Global warming has led to expansion of low-oxygen "underwater deserts" in the tropical oceans over the past five decades, which scientists view as a potential threat to marine ecosystems.
Climate models predict that the trend will continue, potentially threatening marine ecosystems, a report published in Nature magazine said. The discovery, it said, concerns a layer of the ocean called the 'oxygen-minimum zone', where concentrations of dissolved oxygen are particularly low.
The new study shows that this zone has been expanding both upwards and downwards into the adjacent layers in tropical waters. Climate models, according to the report, predict that warming of the sea surface as a result of human activity will hamper the mixing of oceanic waters, preventing dissolved oxygen from mixing evenly through the water column. The new results suggest that this process has already begun. Researchers led by Lothar Stramma of the University of Kiel, Germany, measured oxygenation of oceans at depths of between 300 and 700 metres during a series of observation cruises in tropical regions of the world's three main oceans, Nature reported.
The scientists added their new data to previous oxygen measurements to build up a picture of the trend over the past 50 years. Overall levels of oxygen have dropped in these zones, Stramma and his colleagues found. Regions of the eastern tropical Pacific Ocean and the northern reaches of the Indian Ocean are now classed as 'suboxic' meaning that the amount of oxygen has dropped sufficiently to harm the functioning of ecosystems. In suboxic waters, nitrogen cannot react with oxygen to form biologically available nitrate. This means that organisms at the base of food chains, such as plankton, do not get enough nutrients to survive, Stramma explained in the report.
Environmentalists divided about burying CO2
OSLO: Greenpeace and more than 100 other environmental groups denounced projects for burying industrial greenhouse gases on Monday, exposing splits in the green movement about whether such schemes can slow global warming.
Many governments and some environmental organisations such as the WWF want companies to capture heat-trapping carbon dioxide from the exhausts of power plants and factories and then entomb them in porous rocks as one way to curb climate change.
But Greenpeace issued a 44-page report about the technology entitled "False Hope". "Carbon capture and storage is a scam. It is the ultimate coal industry pipe dream," said Emily Rochon, climate and energy campaigner at Greenpeace International and author of the report.
Greenpeace and 112 green groups from 21 nations said governments should invest in wind, solar and other renewable energies rather than in capture technologies that would allow coal-fired power plants to stay in operation.
In a statement linked to the report, Greenpeace and allies including Friends of the Earth International said the "false promise" of carbon capture and storage (CCS) "risks locking the world into an energy future that fails to save the climate".
But some other environmental groups accept carbon capture as a way to slow rising temperatures and avert more powerful storms, heatwaves, droughts, disrupted monsoon rains and raised world ocean levels.
"Carbon capture and storage is not an ideal solution, but it buys us time," said Stephan Singer, head of the WWF's European Climate and Energy Programme in Brussels.
"We believe it is part of the solution -- an emergency exit." The UN Climate Panel has said CCS could be one of the main ways for slowing climate change by 2100 -- contributing a bigger share of greenhouse gas cuts than energy efficiency, a shift to renewable energy or a push for nuclear power.
Singer said China was opening one or two coal-fired power plants a week and, with a lifetime of 40 years, the world needed ways to retrofit plants to capture emissions rather than expect Beijing to close them down.
Greenpeace said carbon capture technology was largely unproven, could not be deployed on a large scale before 2030, was expensive and brought risks of leaks.
It said it would mean electricity price hikes of between 21 and 91 per cent. But Oslo-based environmental group Bellona said 34 CCS projects were being planned in Europe alone.
"If you exclude CCS in the battle against climate change, you don't take global warming seriously," said Bellona head Frederic Hauge. Several national branches of Friends of the Earth did not sign up for the statement criticising CCS.
"We believe that CCS will be an important tool to reduce emissions from existing coal and gas-fired power plants," said Lars Haltbrekken, head of Friends of the Earth Norway. "We don't support new coal-fired power plants, even with CCS."