Image: Flickr/NASA Goddard Photo and Video
Scientists who traveled to the Arctic on a NASA research cruise last summer were looking for signs of climate change. What they found was a secret world hidden beneath the region's cap of sea ice.
During their travels through the Chukchi Sea off the coast of Alaska, they were stunned to find massive blooms of phytoplankton under the ice -- in water so teeming with the microscopic plant life that it turned an opaque, vivid green. The discovery upends the notion that the sea ice that forms in autumn ushers in a cold, dark and nearly lifeless season for the ocean below.
"This is what you live for as a scientist," said Don Perovich, a sea ice expert at Dartmouth College and co-author of the study, published yesterday in the journal Science. "It's unexpected. It's pure discovery."
Lead author Kevin Arrigo, a biological oceanographer at Stanford University, said the findings amount to "a fundamental shift in our understanding of Arctic ecosystems."
"Clearly there are parts of the Arctic Ocean that are much more biologically productive than we thought," he said.
The scientists believe the blooms are a result of changes in the region's sea ice, which is receding and thinning as the climate warms.
"Decades ago, there would have been thick multiyear ice in this area, maybe 3 meters thick -- 9 to 10 feet," Arrigo said. "No way there would have been sunlight getting through ice that thick to have a bloom like this."
But these days, the portion of the Chukchi Sea the scientists studied is covered with 3-foot-thick "first year" sea ice that forms in the fall and melts in the spring.
More sunlight = phytoplankton bloom
More sunlight is able to penetrate that thinner ice, an effect compounded by declines in snowfall and a proliferation of melt ponds on the ice surface.
Those ponds "are windows from the sky to the ocean," Perovich said. "They transmit about 50 percent of the sunlight that's visible on the surface."
And that light, combined with nutrient-rich waters under the ice, is a recipe for a phytoplankton explosion.
"The amount of phytoplankton in this bloom -- top to bottom -- is more than has ever been seen in any bloom anywhere in the world, in open water," said Arrigo, who has studied phytoplankton for 25 years.
He compared the plankton-filled water to "pea soup." The dense blooms, more than 150 feet deep in places, extended from the ice edge more than 70 miles into the interior of the ice pack.
Although the researchers examined a small portion of the Chukchi Sea, they believe that in roughly 25 percent of the Arctic, conditions are ripe for similar plankton mega-blooms.
The possibility that the phenomenon is so widespread suggests scientists have underestimated the amount of carbon dioxide pulled into the Arctic Ocean by phytoplankton -- which pull CO2 from the atmosphere to make energy -- and animals that consume them.
An early feast for whom?
And the blooms may play into a growing disconnect between the coming of spring and the annual northward journey of wildlife seeking a tasty phytoplankton meal.
The Arctic's open-water plankton blooms now begin about a month earlier than they did in the 1990s, a consequence of the warming climate. Scientists worry that is throwing off the timing of migratory animals like Arctic terns, snow geese and California gray whales that once arrived to feed at the height of the yearly phytoplankton bloom.
The discovery that massive blooms of plankton begin before Arctic sea ice starts to melt in the spring changes the picture slightly.
"Under-ice blooms are going to be good for anything that eats off the bottom," Arrigo said, because they begin when there are fewer predators in the water column to consume the plankton -- meaning more of the tiny organisms will fall to the ocean floor.
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11 Comments
Add CommentWouldn't it be fascinating if this turns out to be some sort of inadvertent self-balancing mechanism? Melting of ice from global warming produces bloom of aquatic flora which intern reduces available CO2- unlikely but possible.
Reply | Report Abuse | Link to thisI Watched on You-tube a video that claims the solar system is heating from the outside in. The video alleges that neither the sun nor the CO2 is responsible.
Reply | Report Abuse | Link to thisOn youtube you can find all types of garbarge.
Reply | Report Abuse | Link to thisThat'd be great if it were true. In that case atmospheric co2 levels should soon begin to diminish...
Reply | Report Abuse | Link to thisWhile an increase in phytoplankton blooms is certainly going to help lower CO2 concentrations in the water, the increased albedo of the darker water near the surface, that was once ice, will add to the warming effect. It is also a forewarning of the increasing CO2 in the atmosphere and more a harbinger of change that will effect other aspects of the arctic ecosystem. Whether that is good or bad in the long term is not yet clear. It could backfire on the environment if the grazing animals that keep it in check don't arrive in time.
Reply | Report Abuse | Link to thisComplex ecosystems defy attempts to fully understand all the consequences of rapid change.
@Alan,
Reply | Report Abuse | Link to thisAlan Says: Watched on You-tube a video that claims the solar system is heating from the outside in. The video alleges that neither the sun nor the CO2 is responsible.
Trent Says:I saw a youtube video that claimed the Queen of England was a reptilian wearing a body suit to disguise it. Amazing the nonsense you can find on the Internet, eh?
Une cascade de pensées.
Reply | Report Abuse | Link to thisL'attraction
du soleil est
comme la
chanson qui
vient dans
la brume
en donnant
une poésie...
Francesco Sinibaldi
Adding to Singing Flea's observations, the phytoplankton taking up CO2 accelerates ocean acidification. On balance, there's a reason for optimism because it does provide nutrients for the food web, and it could provide the Arctic Ocean equivalent of a 'desert rainy-season bloom'.
Reply | Report Abuse | Link to thisHowever, don't put too much stock in the 25% extrapolation. The Arctic Ocean basin is in a state of serious disruption - massive warm inflows from the Atlantic, methane bursts in the East Siberian Sea, a gigantic freshwater gyre in the Beaufort Sea, increased freshwater from Greenland, and massive reductions in sea-ice level. The lack of history about the plankton bloom may have a simple explanation - this is a context phenom similar to plankton blooms around river delta dead zones.
I am a Biology student from Mexico, I found this discovery both fascinating and defining.
Reply | Report Abuse | Link to thisIs there somewhere I can find the complete article, besides Science Magazine?
If you have access to a university library you may find the journal "Science" among its subscriptions.
Reply | Report Abuse | Link to thisSince I don't, I extracted the little information available in this ClimateWire service blurb: I Googled ""Kevin Arrigo" "Don Perovich" arctic phytoplankton". Picking the first item listed, it happened to contain a link to the Science article: http://www.sciencemag.org/content/early/2012/06/06/science.1215065
From that I got the title, & Googled "Massive Phytoplankton Blooms Under Arctic Sea Ice". Among the items listed (mostly news reports), I found one that mentioned "PDF" - it is adownload of the "Science" article:
http://spg.ucsd.edu/people/Greg/Publications/ArrigoK_2012_Brevia.pdf
I can't determine whether this is an authorized copy...
Best wishes!
I forgot to mention - because this was part of a NASA project, there's a wealth of additional informaton available. Please see:
Reply | Report Abuse | Link to thishttp://www.nasa.gov/topics/earth/features/ocean-bloom.html