Dumping iron in the ocean could slow global warming, say scientists

SeaWiFS image of the northeastern Pacific Ocean acquired on July 29, 2002,
showing the SERIES iron-fertilized bloom at bottom center

From CSMonitor

Dumping iron in the seas can help transfer carbon from the atmosphere and bury it on the ocean floor for centuries, helping to fight climate change, according to a study released last week
.
The report, by an international team of experts, provided a boost for the disputed use of such ocean fertilisation for combating global warming.
But it failed to answer questions over possible damage to marine life.

When dumped into the ocean, the iron can spur growth of tiny plants that carry heat-trapping carbon to the ocean floor when they die, the study said.
Scientists dumped seven tonnes of iron sulphate, a vital nutrient for marine plants, into the Southern Ocean in 2004.
At least half of the heat-trapping carbon in the resulting bloom of diatoms, a type of algae, sank below 1,000 metres (3,300 ft).
"Iron-fertilised diatom blooms may sequester carbon for timescales of centuries in ocean bottom water and for longer in the sediments," the team from more than a dozen nations wrote in the journal Nature.

Burying carbon in the oceans would help the fight against climate change, caused by a build-up of carbon dioxide in the atmosphere that scientists say is raising temperatures and causing more floods, mudslides, droughts and higher sea levels.
The study was the first convincing evidence that carbon, absorbed by algae, can sink to the ocean bed. One doubt about ocean fertilisation has been whether the carbon stays in the upper ocean layers, where it can mix back into the air.
A dozen previous studies have shown that iron dust can help provoke blooms of algae but were inconclusive about whether it sank.
Large-scale experiments with ocean fertilisation using iron are currently banned by the international London Convention on dumping at sea because of fears about side-effects.

Twelve small experiments over the last decade in several ocean locations (red dots) consistently showed that intentionally adding iron results in phytoplankton blooms.

(Data courtesy of NASA SeaWiFS Project.)

"Crying shame"

"I am hoping that these results will show how useful these experiments are," lead author Victor Smetacek of the Alfred Wegener Institute in Germany told Reuters.
"It's a crying shame, honestly," he said of the moratorium, which he said meant that even small-scale experiments were too complex and costly for researchers.
He said that ocean fertilisation should be overseen by the United Nations and should not be eligible for carbon credits under U.N. treaties.
He said private companies should not be allowed to run experiments so that proper oversight can be ensured.
Ocean fertilisation is one of several suggested techniques for slowing climate change known as "geo-engineering".

Other possibilities include reflecting sunlight with giant mirrors in space.
"Most scientists would agree that we are nowhere near the point of recommending ocean iron fertilisation as a geo-engineering tool," Ken Buessler of the Woods Hole Oceanographic Institution in the United States wrote in a commentary in Nature.
But he added that many thought that bigger and longer experiments were needed to see if the technology worked.

"If the 50 percent figure for algal bloom biomass sinking to the deep ocean is correct then this represents a whole new ball game in terms of iron fertilisation as a geo-engineering technique," said Dave Reay, a senior lecturer in carbon management at the University of Edinburgh who was not involved in the study.
"Maybe such deliberate enhancement of carbon storage in the oceans has more legs than we thought but, as the authors acknowledge, it's still far too early to run with it," he said.

Smetacek said the publication had been delayed since 2004 partly because of problems in checking that the 150 square km (60 square miles) patch of ocean where the iron was dumped - an eddy in the Antarctic Circumpolar Current - had not mixed with waters outside.
The experts said that the input of iron was similar to that found after the melt of icebergs in the oceans - iron concentrations in coastal regions tend to be much higher.

Links :

• WHOI : Exploring Ocean Iron Fertilization: the scientific, economic, legal and political basis (articles)
• LiveSciences : Could fertilizing the oceans reduce global warming?
• TheGuardian : Dumping iron at sea can bury carbon for centuries, study shows
• Wired : Algal blooms could have caused last ice age / Geoengineering could backfire, make climate change worse
  

Image of the week : Bora-Bora

Pléiades image of Bora-Bora (French Polynésie) -image HR-
>>> geolocalization with the Marine GeoGarage <<<

Alex Gray chasing giants

Other video (Teahupoo)

This is a fresh look at Alex Gray and his exploits from the last year.
Putting Alex Gray into words is a difficult thing because words can’t even describe who Alex is.
Alex Gray is one of the most unique people on the planet.
He is a pro surfer, world traveler, comedian, ladies man, nudist, lobster diver, yoga god, paddler, and inspiration to many.
He grew up in the South Bay of Los Angeles and still loves to come home and spend time with his family after long trips around the world.
He is one of the stars of The Drop Zone and has even co hosted the Surfer Poll Awards.
He has a heart of gold, balls of steel and the summer of 2011 was the Summer of Alex Gray scoring some of the biggest, heaviest and best waves on the planet.

Glaciers calving : cause for worry ?

The Petermann Glacier in northern Greenland has calved an iceberg twice the size of Manhattan, scientists say.
Images from a NASA satellite show the island breaking off a tongue of ice that extends at the end of the glacier.

From BBC

The increasingly detailed and immediate pictures that we get of vast movements of ice at the Earth's poles make for a dramatic sight.

 Polar explorer Eric Philips looks down into one of the 'cracks' in the Petermann Glacier last year

But whether that drama is cause for worry is an open question.

Floating "tongues" of ice, like the one that has broken off the Petermann glacier reported on Thursday, extend beyond the glaciers, and are constantly fed by ice pouring off the ice sheet.
Eventually parts of these tongues break off under the forces surrounding them and become free-floating icebergs.

 >>> geolocalization with the Marine GeoGarage <<<

Thousands of these "calving events" happen in Greenland each year, ranging from the unremarkable to the striking.

On August 5, 2010, an enormous chunk of ice, roughly 97 square miles in size, broke off the Petermann Glacier, along the northwestern coast of Greenland. The glacier lost about one-quarter of its 40-mile long floating ice shelf, the Northern Hemisphere's largest. It's not unusual for large icebergs to calve off the Petermann Glacier, but this new one is the largest to form in the Arctic since 1962. 

This most recent calving is neither of the two in terms of size; with an area of roughly 120 sq km (46 sq mi), it is about half the size of the iceberg that broke off the same glacier in 2010.
Looming larger in the future is the breakup of the Pine Island Glacier in Antarctica - which already shows a 30km-long crack - which could happen any day.
And they get far, far bigger than that.

Northern exposure

It is important to keep in mind that this is a natural and periodic process that has been going on since long before we were here to snap satellite photos.
What is at issue is whether or not the frequency of the events is changing, and why.

In the debate surrounding those questions, there are facts, educated guesses, and worrying trends.
The truth is that the questions are devilishly difficult to answer - the stability of ice sheets at both the Earth's poles depends on a wide range of factors: atmospheric temperatures, the temperatures of the surface of the sea, and the degree of sea ice cover, to name just a few.

The Pine Island glacier will eventually cut loose an 800sq km iceberg

One fact is that the Petermann glacier's margins have now retreated to a point not seen in the last 150 years.

Another is that Greenland has over the last two decades experienced a significantly higher atmospheric warming than the global average.
Yet another is that over that same period, the south of Greenland has seen "mass loss" - both the kind of calving seen at Petermann and simple melting of surface ice - increasing year on year.
And levels of Arctic sea ice cover - which can literally shore up some of Greenland's ice sheet - are on track to be among the lowest ever recorded.

But from there, it becomes educated guesses.

Estimates of the speed of mass loss, for example, have gone back and forth among groups of scientists (and the 2011 edition of the revered Times Atlas got it wrong altogether).

And it remains guesswork to determine whether that worrying mass-loss trend is making its way northward.
"To date, we've not really seen such a strong signal in northern Greenland - and Petermann is right at the northern limit of the ice sheet," said Jonathan Bamber, director of the Bristol Glaciology Centre at the University of Bristol.
"I think it's too early to say that this is the start of increased mass loss from northern Greenland - but it's certainly not good news," Prof Bamber told BBC News.
"Whether it's news that we should be particularly concerned about I think is difficult to answer at this stage."

'Not surprising'

In truth, the buildup and breakup of glaciers can change over timescales ranging from months to millennia, and scientists simply haven't been watching this closely for very long.

As is so often the case in science, what is needed are more observations.
"If we start seeing patterns of the calving front retreating over a range of quite a few glaciers in northern Greenland in the same sector, then we would be quite concerned - and that would be a strong indicator that there's a change taking place, related to either atmospheric warming or ocean warming," Prof Bamber said.

For now, glaciologists - working with Earth and climate scientists of every stripe - are loath to make an explicit connection between iceberg formation and the broader debate around climate change, and this is where worrying trends come in again.
"I can't say that yes, this calving event is a consequence of the marked atmospheric warming that's been taking place over Greenland in the recent decades, but it is certainly more likely to take place as a consequence of that warming," Prof Bamber said.
"You don't have to be a rocket scientist to realise that in a warming world, ice is going to melt - so it's not surprising that Greenland is responding."

Links :

• TheGuardian : Greenland glacier calves iceberg twice the size of Manhattan
• ESA : Earth from Space: Pine Island cracked
• UDEL : Greenland glacier loses ice
• Icy Seas :  New Petermann Ice Island forming July-16, 2012

Rip currents: the ocean's deadliest trick

From LiveScience

Year after year, the ocean's most successful killer is not the great white shark.
It's not the deadly jellyfish.
Not even monster waves or hurricane-force winds.
Your worst ocean nightmare during a day at the beach is more likely to be a rip current, experts say.

Every year more than 100 beachgoers drown in these strong rushes of water that pull swimmers away from the shore.
And that's just in the United States.
Nearly half of all rescues made by lifeguards at ocean beaches are related to rip currents, according to the United States Lifesaving Association.
Sharks typically kill about 6 people a year globally.

A common perception is that rip currents pull you underwater, but in reality they're roughly horizontal currents that gradually suck you further and further from the beach.

A rip current near Melbourne, Fla., after Hurricane Jeanne (NOAA)

Here's how they originate: Waves break differently at different parts of a shore — in some places the waves are strong and in others they are weak.
These differing conditions carve out channels in sand bars that lie just off the beach.
When water returns to the ocean, it follows the path of least resistance, which is typically through these channels.

This creates a strong and often very localized current capable of sweeping unsuspecting swimmers out to sea.
The currents usually move at one to two feet per second but stronger ones can pull at up to eight feet per second. (On a track, Olympic sprinters cover about 34 feet per second.)

Heavy breaking waves can trigger a sudden rip current, but rip currents are most hazardous around low tide, when water is already pulling away from the beach.

Hurricanes, widely spaced swells, and long periods of onshore wind flow can also drum up stronger than normal currents.
These conditions also create larger waves, which sometimes draw more people into the water.

What to do

It is easy to be caught in a rip current.
Most often it happens in waist deep water, experts say.
A person will dive under a wave, but when they resurface they find they are much further from the beach and still being pulled away.

What they do next can decide their fate.

Those who understand the dynamics of rip currents advise remaining calm.
Conserve energy.
A rip current is like a giant water treadmill that you can't turn off, so it does no good to try and swim against it.

The National Oceanic and Atmospheric Administration (NOAA) and the United States Lifesaving Association (USLA) suggest trying to swim parallel to the shore and out of the current. Once you've gotten out of the current, you can begin swimming back to shore.

However, if it is too difficult to swim sideways out of the current, try floating or treading water and let nature do its thing.
You'll wash out of the current at some point and can then make your way back to shore.

If neither of these options seems to be working for you, continue treading water and try to get the attention of someone on shore, hopefully a lifeguard.

The NOAA also emphasizes anyone planning to swim in the ocean should learn to swim well and never swim alone.
Pick a beach with a lifeguard if you don't feel comfortable with your swimming abilities but still want to enjoy the surf.
And finally, take a look at the water -- if it looks dangerous, don't even try it.