Iowa's green energy policy struggle

By Scott Simon BBC News, Iowa

The presence of prairie winds and rich soil makes Iowa literally fertile ground for developing alternative energy sources from wind turbines and biofuels.

Iowa invested $6m in wind turbine manufacturing

But the landscape is also a reminder that achieving energy independence is a formidable challenge and making an agricultural economy green is not easy.

Farm workers cannot take subways to work, farmers have to drive long distances into the fields to sow and harvest their crops and to deliver them to markets.

Farm animals themselves, not to put too fine a point on it, produce methane - a powerful greenhouse gas - that is trapped in the atmosphere.

Those challenges have not stopped the state setting itself ambitious goals.

Energy pioneers

The Iowa Climate Change Advisory Panel recently wrote a report for Governor Chet Culver setting out how the state can reduce carbon emissions by 90% by 2030.

The state has set up an Office of Energy Independence - surely the perfect place, I thought, to test how easy it will be for President Obama to achieve energy independence for the whole of America.

There are plenty of energy pioneers to be found in Iowa.

I feel like I'm doing something more than just building a washing machine, I'm building something for everyone to capitalise on Crugar TuttleWind turbine factory worker

Roger Neuberger, a farmer, lives near Clear Lake in the north-west part of the State - where the wind blows hardest.

He gets money from an energy company each year for making room for two wind turbines on his land.

Mr Neuberger has promised the energy company that he will not publicly reveal how much he is being paid, but other farmers have let it be known that, depending on when their contracts were signed, they can receive somewhere between $2,000 (

Diary: Protecting mountain gorillas

In July 2007, armed men entered the Democratic Republic of Congo's Virunga National Park and killed five critically endangered mountain gorillas at point-blank range, leaving the bodies where they fell.

Since September 2007, rebel forces have controlled the area, threatening to kill any conservationists or gorilla rangers who attempted to enter the area.

Recently, the rangers and their families had to flee from their homes and live in makeshift camps as the latest outbreak of violence engulfed the eastern part of the country.

Diddy and Innocent are long-serving rangers who have spent their working lives protecting the remaining gorillas in the war-torn region.

In this weekly diary, they describe life on conservation's frontline and the frustration of how current events are hampering their efforts.

Profiles of Diddy and Innocent

FRIDAY 30 JANUARY - DISARMING MILITIAS

Last week, I went on a mission with the traditional leader, called a Mwami Ndezi, of more than two million people in North Kivu in a last minute effort to plead with militias in the park to put their weapons down and turn themselves in.

There are efforts to disarm and disband the militia groups

The joint operation between the Rwandan and Congolese armies had just begun, targeting the FDLR militias.

As always, the real victims in the fighting will be the unarmed innocent civilian population, so the Mwami's position was simple:

If militias can be convinced to disarm and demobilise, the battle will be shorter and civilian lives will be spared.

The Congolese and Rwandan forces say that any militias can put down their weapons and join the voluntary disarmament process; those that refuse will be disarmed by force.

Voluntary disarmament needs a bit of explanation. The process is known as DDR (disarmement, demobilisation and reintegration), and applies to Congolese armed groups such as the Mai-Mai or DDRRR.

Some of the Mai-Mai fighters were hardly into their teens

DDR also includes repatriation to Rwanda and resettlement for non-Congolese militias, such as the FDLR.

The UN's peacekeeping mission in Congo, Monuc, is one of the key players in this process, and also took part in the our joint effort with the Mwami.

We left early in the morning for the talks, and after a few hours we suddenly came across Rwandan soldiers on the move.

There must have been about 2,000 soldiers, in single column, walking along the road.

It was a startling reminder that the clock was ticking, and time was not on our side.

A long, dusty drive brought us to Ishasha in the early afternoon, and from there we entered the park and travelled to the fishing village of Nyakakoma on the edge of Lake Edward.

When we arrived, we were surrounded by militiamen, all bearing arms and many of them smelling of alcohol.

Pierre (left) and the Mwami hoped to convince the militia to disarm

Some of them looked like they were barely into their teens.

These children are now potential targets in a massive onslaught by two national armies, by now a matter hours away.

The Mwami called a meeting with the Mai-Mai and FDLR leaders, and my hopes were not that high at first.

How do you convince a militia leader to give up his weapon and hand himself in to the authorities?

After about one hour, the militia commanders retired to make their decision. When they returned, amazingly, they agreed.

The Mwami had convinced them to co-operate and to come back with us and to hand themselves in to the Congolese military authorities.

In all, seven Mai-Mai and one FDLR agreed to come back to Ishasha with us.

They were to hand themselves in with their weapons, and then work out the procedure for their troops to follow.

They should all get conscripted into a training programme and will then either be integrated into the army or demobilised with some training to begin a new life.

Emmanuel de Merode, Virunga National Park director

FRIDAY 23 JANUARY - BEGINNING OF THE END?

Could the arrest of Laurent Nkunda signal the end of the conflict Rwanda arrests Congo rebel leader

We have been receiving reports that CNDP leader Laurent Nkunda was arrested last night.

I don't know how it seems from the outside, but for us living through these events, it started with disbelief, then confusion, followed by amazement.

Right now, we don't dare hope that peace is finally here.

Last week, Bosco - a very senior CNDP commander - announced a comprehensive ceasefire with the Congolese army.

It was unclear if this was the official CNDP position, and many of us didn't pay much attention to it.

However, it soon transpired that the Rwandan chief of staff was present, together with senior Congolese military officers; that's an unusual mix.

Soon after, CNDP then formally confirmed the ceasefire.

Earlier this week, there were reports of significant Rwandan army movements into Congo. We had heard this before, and I don't always believe it.

Rwandan military moving into Congo is not a joking matter. But suddenly, there they were calmly marching past our park station at Rumangabo.

Snares have been one of the biggest threats to the wildlife in recent months

On Thursday, we looked on as truckloads of Congolese military crossed the battlefronts into CNDP territory.

Now, they're all working together: Rwandan army, Congolese soldiers and the CNDP rebel force.

It remains to be seen what will happen to General Nkunda himself.

The rangers of Virunga National Park have been working under very difficult conditions during the war.

Many have been displaced with their families, some have been caught in the crossfire, and several have died in the line of duty.

We hope that this week marks the beginning of the end of this conflict and that the rangers can get back to work protecting wildlife.

In particular, there is much to be done in the area of the park that had until now been the front-line, such as monitoring the population of mountain gorillas and destroying the hundreds of snares that have been placed in the forest during our absence.

Emmanuel de Merode, Virunga National Park director

MONDAY 19 JANUARY - MILITIA KILL RANGER

Safari had a promising future in conservation ahead of him

It is with great sadness that we have to share the news with you that one of our rangers, Safari Kakule, has been killed.

Safari was at our patrol post in Tshiaberimu with six other rangers last week when they were attacked without warning by Mai Mai militia.

The team of rangers defended their position and managed to apprehend a Mai Mai officer.

But the attack was extremely violent and they were greatly outnumbered. As they retreated from their position, Safari was hit by the attackers' gunfire.

Safari was an exceptional ranger, who had worked with the gorillas in Tshiaberimu for several years.

Happier times: Safari poses for a photo with communications officer Pierre

He had recently trained to be a para-vet, and he was expected to play a very important role in protecting the gorillas of Tshiaberimu.

His colleagues carried Safari's body with them as they moved to safety and brought it to Kyondo, several hours from where the attack took place.

From there he will be taken back to Lubero, and a final resting place at his family home.

It may not look like it in the photo, but Safari was a big guy. What the picture does not show is that I am actually standing on a mound of earth just to be level with him.

He was intelligent, committed, and knew a lot about gorillas.

In my mind, he was someone who would go on to big things and would have made an important contribution to conservation in Virunga.

He will be greatly missed.

Pierre Peron, Virunga National Park communications officer

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Read the previous diary entries from Diddy and Innocent:

August - October 2007

November 2007 - January 2008

February - July 2008

August - December 2008

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Profile of the rangers:

Innocent -

Head of gorilla monitoring in the Mikeno sector. He has worked in Virunga National Park more than 10 years. His father is a patrol post chief. His brother was also a high-level ranger, but was killed in the line of service in November 1996.

Diddy -

Head of tourism in the southern sector of Virunga National Park. He has been a ranger for 18 years and started working with the gorillas in the Mikeno Sector in 1991. He was forced to flee from his work from 1997-2001 during the nation's civil war.

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MS stem-cell treatment 'success'

MS causes damage to nerve cells

Stem-cell transplants may control and even reverse multiple sclerosis symptoms if done early enough, a small study has suggested.

Not one of 21 adults with relapsing-remitting MS who had stem cells transplanted from their own bone marrow deteriorated over three years.

And 81% improved by at least one point on a scale of neurological disability, The Lancet Neurology reported.

Further tests are now planned, and a UK expert called the work "encouraging".

MS is an autoimmune disease which affects about 85,000 people in the UK.

It is caused by a defect in the body's immune system, which turns in on itself, causing damage to the nerves which can lead to symptoms including blurred vision, loss of balance and paralysis.

Stem cells are showing more and more potential in the treatment of MS and the challenge we now face is proving their effectiveness in trials involving large numbers of people Dr Doug Brown, MS Society

At first, the condition mostly causes intermittent symptoms that are partly reversible.

Over a 10-15 year period after onset, most patients develop secondary-progressive MS, with gradual but irreversible neurological impairment.

It is not the first time this treatment - known as autologous non-myeloablative haemopoietic stem-cell transplantation - has been tried in people with MS, but there has not been a great deal of success.

The researchers at Northwestern University School of Medicine in Chicago said most other studies had tried the transplants in people with secondary-progressive MS where the damage had already been done.

In the latest trial patients with earlier stage disease who, despite treatment had had two relapses in the past year, were offered the transplant.

Immune system

Stem cells were harvested from the patients and frozen while drugs were given to remove the immune cells or lymphocytes causing the damage.

The stem cells were then transplanted back to replenish the immune system - effectively resetting it.

Five patients in the study relapsed, but went into remission after receiving other therapy.

The researchers are now doing a randomised controlled trial in a larger number of patients to compare the treatment with standard therapy.

Study leader Professor Richard Burt said this was the first MS study of any treatment to show reversal of damage.

"You don't want to wait until the horse has left the barn before you close the barn door - you want to treat early.

"I think the reversal is the brain repairing itself.

"Once you're at the progressive stage you have exceeded the ability of the brain to repair itself," he said.

However, he cautioned that it was important to wait for the results of the larger trial.

And that he would not call it a cure but "changing the natural history of the disease".

Dr Doug Brown, research manager at the MS Society, said the results were very encouraging.

"It's exciting to see that in this trial not only is progression of disability halted, but damage appears to be reversed.

"Stem cells are showing more and more potential in the treatment of MS and the challenge we now face is proving their effectiveness in trials involving large numbers of people."

UK energy saving policy 'failing'

By Mark Kinver Science and environment reporter, BBC News

The Energy Saving Trust wants to see less heat and more action

The UK government is failing to support its own measures designed to deliver energy savings, an expert has warned.

Philip Sellwood, chief executive of the Energy Saving Trust (EST), said local authorities needed more funds in order to ensure savings were being made.

While ministers were quick to promote new policies such as "zero carbon homes", existing building regulations were not being upheld, he added.

Under EU commitments, the UK has to deliver 20% energy savings by 2020.

"To me, this highlights a real gap between the aspiration to do something appropriate and the actual delivery on the ground," Mr Sellwood told BBC News.

"If it were just a matter of policy announcements, the UK would be up among the leading countries.

"Our building regulations in the UK are among some of the toughest in Europe, but they are extremely poorly enforced as far as energy efficiency goes."

Simple fixes

He said research showed that, in some cases, up to 30% of properties being built would fail existing building regulations.

"When you think that we are putting a lot of reliance on meeting our CO2 reduction targets by increasing the toughness of our building regulations, this is a real concern."

Concern over 'zero carbon' homes

The Climate Change Act, which became law late last year, requires future governments to cut carbon dioxide by 80% from 1990 levels by 2050.

Households in the UK are estimated to be responsible for almost 20% of the nation's greenhouse gas emissions, meaning that failure to cut CO2 emitted by homes will threaten any attempt to achieve the legally binding target.

Mr Sellwood said the failings were occurring in areas that did not require technical expertise.

"It is simple things like people not fitting windows or doors correctly. Instead of getting energy efficiency, we are getting energy inefficiencies."

He added that there were too few inspections being carried out in order to spot the shortfalls.

He warned that the current situation on the ground did not bode well for the government's commitment that all new homes from 2016 had to be "zero carbon".

"If there is no proper enforcement of the building regulations, we won't know if what has been built is the same as what was promised."

To overcome the shortfall in building inspectors, Mr Sellwood said that it was important for local authorities to receive the necessary resources in order to uphold the regulations.

Acting smart

Another policy area he said that was failing to live up to expectations involved "smart meters".

"A short while ago, the government announced that it was going to implement a programme of installing smart meters in people's homes," he explained.

Studies have shown that smart meters can cut bills by up to 10% Bringing meters out of the closet

"This would allow the household to indentify their energy use and obviously take measures to reduce it.

"Since then, there has been silence from the government.

"It could be as long as five to 10 years before we see any tangible change in the number of smart meters in people's homes."

He added that studies in other countries had shown that smart meters had helped cut energy consumption by up to 10%.

The technology, he suggested, would have a number of benefits. Firstly, it would help people save money in a time of financial uncertainty and high energy prices.

Secondly, it would help reduce the demand for energy and cut carbon emissions.

As well as criticising the UK government, the EST has also voiced concerns about possible plans to change the EU's energy efficiency labelling scheme for household goods and appliances.

Mr Sellwood said the current A-G rating system could be replaced by another scheme, even though research suggested that most people recognised it and understood how the A-G format worked.

"We think that the EU has enough on its plate at the moment without trying to change this," he said.

"It is a case of 'if it isn't broken, don't try to fix it'."

Britain warned over air quality

Traffic is a major contributor towards dangerous particles

Britain has been warned by the European Commission for failing to comply with EU standards on air quality.

The body says the UK could face court action if it fails to meet a directive limiting harmful airborne particles.

The particles are emitted mainly by industry, traffic and domestic heating and can cause asthma, heart problems, lung cancer and premature death.

Stavros Dimas, European Environment Commissioner said strict action would follow if standards are not met soon.

A Department for Environment, Food and Rural Affairs (Defra) spokesman said the UK would apply for more time to meet targets.

In June last year, a new European air quality directive came into force. Member states were allowed "limited" extra time to meet the standards which have been in force since 2005.

But Mr Dimas warned: "Air pollution has serious impacts on health and compliance with the standards must be our utmost priority. While the new directive allows time extensions for compliance if certain conditions are met, these must not delay measures to reduce emissions.

We have the measures in place and the extra time will allow those measures to take effect Defra spokesman

"It is also essential that where time extensions are not applicable the standards are fully respected. The flexibility given to member states will therefore be complemented by strict enforcement action by the Commission."

Assuming the extension is granted, the UK would have until 2011 to satisfy the criteria, the Defra spokesman said.

He said he was confident that by then there would be no breaches. "We have the measures in place and the extra time will allow those measures to take effect".

Britain is not alone in its failure to met the EU standards. Only two member states, Ireland and Luxembourg, are within the limits on all criteria - while 11 countries are currently having their applications for time extensions considered.

Persistent failure to comply can lead to a case going before the European Court of Justice, which can impose a financial penalty.

Darwin's twin track: 'Evolution and emancipation'

What drove Charles Darwin to his extraordinary ideas on evolution and human origins? Adrian Desmond, with co-author James Moore, argue in a new book that the great scientist had a "sacred cause": the abolition of slavery.

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A powerful symbol (Courtesy of the trustees of the Wedgwood Museum)

"It makes one's blood boil," said Charles Darwin.

Not much outraged the gentle recluse, but the horrors of slavery could cost him a night's sleep.

He was thinking of the whipped house boy and the thumbscrews used by old ladies in South America, atrocities he had witnessed on the Beagle voyage.

The screams stayed with him for life, but how much did they influence his life's work?

Today you can still read of Darwin's "eureka" moment when he saw the Galapagos finches.

Alas, his conversion to evolution wasn't so simple, but it was much more interesting. It didn't occur in the Galapagos, but probably on his arrival home.

And new evidence suggests that Darwin's unique approach to evolution - relating all races and species by "common descent" - could have been fostered by his anti-slavery beliefs.

Family feelingsAfter circumnavigating the globe (1831-6), Darwin settled in London. Here in 1838 he formulated his theory of "natural selection", after which he became increasingly reclusive, particularly following his move to Down village in Kent.

He refrained from publishing a word on evolution until 1858 - not even a brief, priority-grabbing paper, as was his way with other projects. His hesitance is understandable. Evolution was execrable to his Cambridge friends.

BBC'S DARWIN SEASON The Genius of Evolution

One naturalist called it "abominable trash vomited" out by revolutionaries; and radicals did, indeed, deploy a self-sustaining evolution to undermine the creationist miracles on which Anglican power rested.

Darwin's gouty Cambridge professor, Adam Sedgwick, used "contempt, scorn, and ridicule" to trash one "filthy" evolution book in 1844. Darwin, sensitive about his reputation, wisely laid low.

So why devise such a beastly theory in the first place, if it threatened ignominy? Was there some integral moral gain?

Consider another question. Why was Darwin's evolution uniquely defined by common descent, the joining of races and species through shared ancestry? Darwin's common descent image is so obvious today that we forget to question where it came from.

'Man and brother'

Common descent in Darwin's younger day was ubiquitous in anti-slavery tracts. Consider the words of the famous cameo, depicting a kneeling slave asking "Am I Not a Man and a Brother?" That cameo was in fact the brainchild of the pottery-dynasty founder, Josiah Wedgwood, Darwin's grandfather.

New evidence shows how indebted Darwin was to this anti-slavery heritage.

Darwin knew that going into print would have invited derision

Darwin's uncle Jos Wedgwood sold the firm's London showroom, and ploughed the proceeds into an anti-slavery society, and in the 1850s (with American slavery still flourishing) the Wedgwoods continued using labels showing the slave under Britannia's banner, which read "God Hath Made of One Blood All Nations of Men".

The anti-slavery agitator Thomas Clarkson - the man who rode 35,000 miles collecting statistics in the sea ports on the evil trade - was another bankrolled by Josiah Wedgwood.

With a Wedgwood wife and mother, Darwin saw abolition as a "sacred cause" too, and in his culminating work, the Descent of Man (1871), he placed Clarkson at the moral apex of humanity and called slavery a "great sin".

Such family feelings explain why, as a 16-year-old at Edinburgh University in 1826 (in a period often dismissed by historians), Darwin could spend 40 extra-curricular hours with a freed slave from Guyana studying taxidermy and become his "intimate" friend.

And this when many visiting Americans saw any black/white friendship as "revolting".

Torture accounts

Darwin witnessed slavery everywhere in South America. The Beagle's own supply ship on her previous trip had originally been a slaver, and, once sold, it reverted to slaving. While Darwin was on the continent, it was again disgorging chained Africans.

Darwin's journal of the voyage (1845) gives a damning account of the tortures he saw or heard of; but of all the "heart-sickening atrocities", the worst for him were the stories of masters threatening to sell the children of disobedient slaves.

Darwin was appalled at the treatment handed out to slaves

As an outsider, he was "powerless as a child even to remonstrate". But within weeks of the Beagle's return, he developed a science which undercut the slave-master's notions.

Many plantation owners considered slaves a separate species, an animal to be exploited as such. Blacks and whites shared no joint ancestry.

Yet the Darwin-Wedgwood maxim made the slave a "Man and a Brother". Darwin opened his first evolution notebook in 1837, damned slave-holders for their separate species view, then pushed common parentage to the zoological limit.

Since species were only extended races, they too must share an ancestry. He moved from talking of the common "father" of mankind to an "opossum"-like fossil as the father of all mammals.

Human genealogy became the model for his famous "tree of life".

Fossil evidence

None of this minimizes the importance of Darwin's Galapagos and Pampas observations. The giant tortoises, mockingbirds and finches varied from island to island, and this became clearer to Darwin after London Zoo's bird expert John Gould analysed his finches in January 1837.

Then Richard Owen (the man shortly to give the world the "dinosaurs") diagnosed Darwin's fossils. Darwin thought that some were "rhinos" (Old World mammals), yet Owen showed that they were indigenous giant armadillos, sloths and anteaters.

So extinct animals were being succeeded by related living types. This evidence remains crucial, but it was the way Darwin marshalled it that concerns us. Assuming the tacit truth of racial "brotherhood" allowed him to join the bloodlines into a common descent configuration.

And he did so in 1837-8, just as the West Indies slaves were being released (technically freed in 1833, they were forced to serve an "apprenticeship" which effectively kept them in bondage till 1838).

This freedom filled Darwin with a sense of pride and he declared that "we... have made a greater sacrifice, than ever made by any nation, to expiate our sin". He certainly had.

All too clear

His common descent imagery was unknown elsewhere in natural history, beyond racially unifying works such as James Cowles Prichard's Researches into the Physical History of Mankind. That book traced animal races to common ancestors in order to prove that all humans could have descended from Adam.

Darwin, preparing to write the Origin of Species, scribbled inside his copy of Prichard: "How like my Book all this will be". It wasn't so. He remained a worried man and in the later 1850s dropped humans from his publishing plans because the subject was "so surrounded with prejudices".

But even though the Origin of Species (1859) skirted people, no one doubted that they remained at its core.

Darwin's "bulldog" T.H. Huxley, who took over the fight for human evolution, said that when it came to uniting black and white ancestries, he "was pleased to be able to show that Mr Darwin was for once on the side of orthodoxy".

Darwin could have wished for no more.

Adrian Desmond is an Honorary Research Fellow in the Biology Department at University College London. He is co-author with James Moore of Darwin's Sacred Cause (Allen Lane)

Chemicals 'may reduce fertility'

PFCs may make it more difficult for some women to get pregnant

Chemicals commonly found in food packaging, upholstery and carpets may be damaging women's fertility, say US scientists.

A study published in the journal Human Reproduction measured levels of perfluorinated chemicals (PFCs) in the blood of 1,240 women.

Those with higher levels were more likely to take longer to become pregnant.

UK experts said more research was needed to confirm a link.

PFCs are useful in industry because they are resistant to heat, and have the ability to repel water and oil.

However, high concentrations have been linked to organ damage in animals, and the chemicals have the ability to persist for long periods in the body.

It is an important finding and certainly warrants further detailed research, particularly in those trying for a family Tony RutherfordBritish Fertility Society

The researchers, from the University of California in Los Angeles, analysed blood samples taken at the time of the woman's first antenatal visit, then interviewed the women about whether the pregnancy was planned, and how long it had taken them to get pregnant.

The levels of the chemicals varied from 6.4 nanograms per millilitre of blood - a nanogram is a billionth of a gram - to 106.4 nanograms per ml.

When the group of women were divided into four groups depending on these levels, they found that, compared to women in the group with the lowest readings, the likelihood of infertility - taking more than a year or IVF to get pregnant - was significantly higher for women with higher levels of PFCs in their bloodstream.

Dr Chunyuan Fei, one of the researchers, said that earlier studies had suggested that PFCs might impair the growth of babies in the womb.

She said that more women in the groups with higher exposure to PFCs had problems with irregular menstrual cycles , which might suggest that interference with hormones was the reason.

'Tenuous link'

Professor Jorn Olsen, who led the study, said that the team were now waiting for further studies to confirm the link between fertility problems and PFCs.

Tony Rutherford, chairman of the British Fertility Society, said that the findings were "interesting".

"This research shows a tenuous link in the delay to conception in women with the highest levels of two commonly-used perfluorinated chemicals.

"It is an important finding and certainly warrants further detailed research, particularly in those trying for a family.

"The study emphasises the importance of remaining vigilant to potential environmental factors that may impact on fertility."

Ocean climate fix remains afloat

By James Morgan Science reporter, BBC News

Plankton blooms act as a sponge sucking carbon dioxide out of the atmosphere

Plans to curb climate change by using plankton to draw carbon dioxide into the world's oceans have been boosted.

A spectacular natural algal bloom in the Southern Ocean helped to "lock" carbon away into deep sea sediments, according to a study in Nature journal.

But the amount of carbon stored was not nearly as high as some artificial "geo-engineering" schemes had predicted.

Plans to "seed" plankton blooms by adding iron to oceans are strongly opposed by many green groups.

This is a significant result - it suggests that ocean iron fertilisation might work for reducing atmospheric CO2 Prof Peter Burkill,SAHFOS

The international research team behind the Crozex study say their findings have "significant implications" for plans to mitigate climate change.

They come as scientists resume a controversial ocean fertilisation experiment in the Scotia Sea, east of Argentina.

The Lohafex study had been suspended by the German government after environmental groups protested that it violates the terms of the UN Convention on Biological Diversity.

They fear that adding iron to oceans may damage ecosystems.

Ocean commotion

Using algae as a "biological carbon pump" has been touted as one of the more promising "geo-engineering" schemes for mitigating global warming.

Plankton act as a natural sponge for carbon dioxide - drawing the greenhouse gas down out of the atmosphere and into the sea.

When plankton die, they sink to the bottom of the ocean, locking away some of the carbon they have absorbed.

Experiments suggest that "seeding" oceans with iron can stimulate the growth of plankton - particularly waters which are rich in nutrients.

Researchers set up sediment traps to collect samples of sinking material

But exactly how much carbon sinks to the sea floor, and how long it remains locked away, is still unknown.

In the Crozex experiment, an international research team sailed to the Crozet Islands, in the Southern Ocean, about 2,200km (1,400 miles) southeast of South Africa.

These waters experience a spectacular annual plankton bloom the size of Ireland, 120,000 sq km (46,300 sq miles) fertilised by iron naturally supplied from the islands' volcanic rocks.

The researchers used sediment traps to follow the passage of carbon from the sea surface to the ocean floor.

They found that seawater and sediment samples taken directly beneath the bloom were two-to-three times richer in carbon, compared to samples from a nearby ocean region which was rich in nutrients, but not in iron.

"Our results have significant implications for proposals to mitigate the effects of climate change through purposeful addition of iron to the ocean," said lead author Professor Raymond Pollard, of the National Oceanography Centre, Southampton.

"Our findings support the hypothesis that increased iron supply...may have directly enhanced carbon export to the deep ocean.

"[However] our estimate of carbon sequestration for a given iron supply still falls 15-50 times short of some geo-engineering estimates."

Next steps

"This is a significant result," said Professor Peter Burkill, director of the Sir Alister Hardy Foundation for Ocean Science, Plymouth (SAHFOS).

"It suggests that ocean iron fertilisation might work for reducing atmospheric CO2 through export of carbon into the ocean's interior.

"But the next step from natural experiments to artificial ones is crucial.

"We now need to know what the ecological impacts of artificial fertilisation experiments are."

The SeaSoar was used to measure ocean properties down to 300m

Many scientists doubt whether adding iron artificially will ever seed plankton blooms as successfully as natural iron.

To test the technique, the German government has just re-authorised one of the largest ocean fertilisation experiments to date.

The Lohafex expedition had been suspended, after concerns that it violated the terms of the Convention On Biological Diversity.

But researchers on board the vessel RV Polarstern have now begun seeding six tonnes of iron sulphate over 300 square kilometres of the Scotia Sea, east of Argentina.

"As this paper shows, much larger amounts of iron are being added daily by natural processes around the Crozet Island," said Professor Andrew Watson, University of East Anglia.

"And that doesn't seem to have done the Antarctic ecosystem any harm."

Crucial experiment

"Legitimate experiments like [Lohafex] are crucial to learning more about the effects of iron fertilisation," said Dr Gary Fones, University of Portsmouth, who was part of the Crozex team.

"They will help scientists evaluate the merits of such a scheme."

However, the environmental impact of Lohafex was questioned by Kristina Gjerde, high seas policy advisor, the International Union for Conservation of Nature (IUCN).

She said: "The fundamental question remains, should this activity be allowed to proceed unregulated?

"I am not against research in this area; however, it should follow internationally agreed rules and procedures.

"The Convention on Biological Diversity's call for a defacto moratorium on ocean fertilisation reflects the will of the international community that this activity should not proceed until certain basic requirements have been satisfied.

"The government ministries that authorised the Lohafex experiment did not comply with the rules for [environmental] impact assessments as they currently exist under the London Convention [on the Prevention of Marine Pollution]."