Posted by: thewideblueyonder | December 27, 2008

It’s ‘attack of the slime’ as jellyfish jeopardize the Earth’s oceans

It has been dubbed the “rise of slime.” Massive swarms of jellyfish are blooming from the tropics to the Arctic, from Peru to Namibia to the Black Sea to Japan, closing beaches and wiping out fish, either by devouring their eggs and larvae, or out-competing them for food.

To draw attention to the spread of “jellytoriums,” the National Science Foundation in the U.S. has produced a report documenting that the most severe damage is to fish: In the Sea of Japan, for example, schools of Nomurai jellyfish – 500 million strong and each more than two metres in diameter – are clogging fishing nets, killing fish and accounting for at least $20-million in losses. The Black Sea has suffered $350-million in losses. A region of the Bering Sea is so full of jellies that it was nicknamed “Slime Bank.”

Though the reasons for the rise of jellyfish vary from region to region, in many cases we have ourselves to blame, says Richard Brodeur, an NSF scientist and research fishery biologist with the U.S. National Oceanic and Atmospheric Administration.

In some oceans, climate change is fuelling their growth “because a lot of jellies grow faster and produce more young in warmer waters,” Dr. Brodeur says. In other places, overfishing of large predatory fish such as tuna is the main cause. A major problem, he says, is the introduction of new species – such as those in the Black Sea – through the release of ballast water from regions as far away as the Great Lakes.

Farming is also an issue: Fertilizer runoff causes algae to bloom, soaking up the water’s oxygen and rendering vast areas inhospitable to almost all life – except jellyfish, which “can survive in very low-oxygen conditions where fish cannot,” Dr. Brodeur says. The result is “dead zones,” more than 400 worldwide, covering 25,000 hectares, the NSF says.

What can be done about it? “In some cases, introducing other species that prey on the jellies can control them,” Dr. Brodeur says, but we have to proceed with extreme caution, as thsi risks trading one problem for another.

Origins of climate change

It has been a controversial idea from the start: Did man-made global warming actually start 10,000 years ago?

William Ruddiman of the University of Virginia first proposed the idea in 2003. Last week, Stephen Vavrus, a climatologist at the University of Wisconsin-Madison’s Center for Climatic Research, presented supporting data, gathered with Prof. Ruddiman, to the American Geophysical Union.

The theory posits that the Earth has swung between ice ages and warm temperate interglacial periods for the past million years, with each shift triggered by regular changes in the Earth’s orbit around the sun and fuelled by “positive feedback” effects – such as the loss of ice and snow, which reflect sunlight back to space, and the increase in darker-coloured, less reflective water, soaking up heat and further warming the planet (as is happening right now).

About 5,000 to 8,000 years ago, levels of the greenhouse gases carbon dioxide and methane started to rise more than the levels typical of other post-ice-age periods, based on ice-core records from Antarctica. According to Prof. Ruddiman, the change was caused by human activities, such as clearing forests in Eurasia, releasing carbon dioxide and cultivating rice paddies in Asia, releasing methane. Global warming was promoted by the resulting positive feedback effects – warming the oceans, for example, which lowered their carbon dioxide content (cold liquids, like champagne, hold more gas than warm ones). Even before the start of the Industrial Revolution, the scientists say, levels of methane and carbon dioxide were already accelerated.

Prof. Vavrus presented data from computer simulations done with Prof. Ruddiman. “As computers improve, we can make more sophisticated models that incorporate more and more of the feedback effects together.”

The warming effect from ancient man has prevented an ice age from occurring right now, they say. “If humans hadn’t intervened, it would be two degrees Celsius colder” on the planet over all, Prof. Ruddiman says. “There should be permanent ice sheets covering much of Canada and Eurasia.”

He adds that it doesn’t mean global warming is beneficial: “When my initial paper was published, the climate-change skeptics jumped all over it and said, ‘See, greenhouse gases are our friend,’ ” he says. “But then they realized that if they accepted my hypothesis, it means the climate system is as sensitive as mainstream scientists say it is.”

Eco-friendly Whisky

Raise a glass to drinks conglomerate Diageo, which is building a “green distillery” in Speyside, Scotland – one that will recycle its water, produce 15 per cent of the carbon emissions of an old distillery and cut the heating bill in half by burning used barley. The Rose-

isle plant, the first major distillery to be built in 30 years, is set to open early next year and produce more than 10 million litres of Johnny Walker a year.

Diageo has also announced a greener approach at its Cameronbridge distillery in Fife, with an anaerobic digester costing $120-million – the largest investment in renewable energy in Britain outside the utilities sector. It will recover electricity and energy from the distillery and use it to convert the leftover malt, wheat and yeast into biogas and biomass energy sources, preventing the emission of 56 million tonnes of carbon dioxide a year.

“The scotch industry as a whole is looking at our environmental strategy,” says Campbell Evans of the Scotch Whisky Association. “The production of Scotch depends on our natural resources so it is important for us.” The industry is in the process of deciding on environmental targets to 2020 and 2050, he says.

Benefits of biochar

It has been called a “miracle material” and a “climate saviour” – and it was invented 500 years ago in the Amazon when farmers took the burnt remains of their food and agricultural waste and buried it in the rain forest.

The burnt material – a porous charcoal called “biochar” – enriched and fertilized the soil, which to this day contains up to 70 times more carbon than non-enriched soils, according to scientists at the United Nations Climate Change Conference in Poznan, Poland, this month.

Now, scientists and policy-makers are urging that the post-Kyoto climate treaty – to be decided on in Copenhagen in 2009 – include stipulations that biochar use be widely adopted in order to lock up the carbon from the burnt plant waste and stimulate growth of more plants to remove carbon from the atmosphere. Its use could make existing agricultural lands more productive, and prevent further deforestation.

Zoe Cormier is a science writer based in London.


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