Via Eurekalert: “A new study concludes that an old, fundamental and widely accepted theory of how and why phytoplankton bloom in the oceans is incorrect. The findings challenge more than 50 years of conventional wisdom about the growth of phytoplankton, which are the ultimate basis for almost all ocean life and major fisheries. And they also raise concerns that global warming, rather than stimulating ocean productivity, may actually curtail it in some places.”
I’m skeptical of the claim made about GW “stratifying the oceans, resulting in less mixing” because as we’ve been told many times, A Warming World Means More Destructive Storms.
So, which is it? AGW means more storms? Less storms? A storm free Arctic?
On the plus side, they included the actual paper with the press release at OSU, unlike many universities that hide it behind a paywall from the public, making them pay for taxpayer funded research twice. Kudos to OSU. – Anthony
Media Release
Findings overturn old theory of phytoplankton growth, raise concerns for ocean productivity
The journal publication the story is based on is available online: http://bit.ly/aTUM3V
CORVALLIS, Ore. – A new study concludes that an old, fundamental and widely accepted theory of how and why phytoplankton bloom in the oceans is incorrect.
The findings challenge more than 50 years of conventional wisdom about the growth of phytoplankton, which are the ultimate basis for almost all ocean life and major fisheries. And they also raise concerns that global warming, rather than stimulating ocean productivity, may actually curtail it in some places.
This analysis was published in the journal Ecology by Michael Behrenfeld, a professor of botany at Oregon State University, and one of the world’s leading experts in the use of remote sensing technology to examine ocean productivity. The study was supported by NASA.
The new research concludes that a theory first developed in 1953 called the “critical depth hypothesis” offers an incomplete and inaccurate explanation for summer phytoplankton blooms that have been observed since the 1800s in the North Atlantic Ocean. These blooms provide the basis for one of the world’s most productive fisheries.
“The old theory made common sense and seemed to explain what people were seeing,” Behrenfeld said.
“It was based on the best science and data that were available at the time, most of which was obtained during the calmer seasons of late spring and early summer,” he said. “But now we have satellite remote sensing technology that provides us with a much more comprehensive view of the oceans on literally a daily basis. And those data strongly contradict the critical depth hypothesis.”
That hypothesis, commonly found in oceanographic textbooks, stated that phytoplankton bloom in temperate oceans in the spring because of improving light conditions – longer and brighter days – and warming of the surface layer. Warm water is less dense than cold water, so springtime warming creates a surface layer that essentially “floats” on top of the cold water below, slows wind-driven mixing and holds the phytoplankton in the sunlit upper layer more of the time, letting them grow faster.
There’s a problem: a nine-year analysis of satellite records of chlorophyll and carbon data indicate that this long-held hypothesis is not true. The rate of phytoplankton accumulation actually begins to surge during the middle of winter, the coldest, darkest time of year.
The fundamental flaw of the previous theory, Behrenfeld said, is that it didn’t adequately account for seasonal changes in the activity of the zooplankton – very tiny marine animals – in particular their feeding rate on the phytoplankton.
“To understand phytoplankton abundance, we’ve been paying way too much attention to phytoplankton growth and way too little attention to loss rates, particularly consumption by zooplankton,” Behrenfeld said. “When zooplankton are abundant and can find food, they eat phytoplankton almost as fast as it grows.”
The new theory that Behrenfeld has developed, called the “dilution-recoupling hypothesis,” suggests that the spring bloom depends on processes occurring earlier in the fall and winter. As winter storms become more frequent and intense, the biologically-rich surface layer mixes with cold, almost clear and lifeless water from deeper levels. This dilutes the concentration of phytoplankton and zooplankton, making it more difficult for the zooplankton to find the phytoplankton and eat them – so more phytoplankton survive and populations begin to increase during the dark, cold days of winter.
In the spring, storms subside and the phytoplankton and zooplankton are no longer regularly diluted. Zooplankton find their prey more easily as the concentration of phytoplankton rises. So even though the phytoplankton get more light and their growth rate increases, the voracious feeding of the zooplankton keeps them largely in-check, and the overall rise in phytoplankton occurs at roughly the same rate from winter to late spring. Eventually in mid-summer, the phytoplankton run out of nutrients and the now abundant zooplankton easily overtake them, and the bloom ends with a rapid crash.
“What the satellite data appear to be telling us is that the physical mixing of water has as much or more to do with the success of the bloom as does the rate of phytoplankton photosynthesis,” Behrenfeld said. “Big blooms appear to require deeper wintertime mixing.”
That’s a concern, he said, because with further global warming, many ocean regions are expected to become warmer and more stratified. In places where this process is operating – which includes the North Atlantic, western North Pacific, and Southern Ocean around Antarctica – that could lead to lower phytoplankton growth and less overall ocean productivity, less life in the oceans. These forces also affect carbon balances in the oceans, and an accurate understanding of them is needed for use in global climate models.
Worth noting, Behrenfeld said, is that some of these regions with large seasonal phytoplankton blooms are among the world’s most dynamic fisheries.
The critical depth hypothesis would suggest that a warmer climate would increase ocean productivity. Behrenfeld’s new hypothesis suggests the opposite.
Behrenfeld said that oceans are very complex, water mixing and currents can be affected by various forces, and more research and observation will be needed to fully understand potential future impacts. However, some oceanographers will need to go back to the drawing board.
“With the satellite record of net population growth rates in the North Atlantic, we can now dismiss the critical depth hypothesis as a valid explanation for bloom initiation,” he wrote in the report.
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Warming means more storms which means more nutrients and more mixing, so theory FAIL.
NEXT!!!
Depending on which measurement you use, ocean temperatures are cooling, flat, or warming. No clear trend yet. (Right?)
‘That’s a concern, he said, because with further global warming, many ocean regions are expected to become warmer and more stratified.’
Is this actually happening? Or is it just the hook for more grant money?
Not having a PhD in anything I am probably not the right person to interpret this research. I find the Professor’s reasoning difficult to follow:
1.) ‘As winter storms become more frequent and intense, the biologically-rich surface layer mixes with cold, almost clear and lifeless water from deeper levels. This dilutes the concentration of phytoplankton and zooplankton, making it more difficult for the zooplankton to find the phytoplankton and eat them – so more phytoplankton survive and populations begin to increase during the dark, cold days of winter.’
a. The first sentence is quite clear; the second sentence seems to be contradicting itself, if there’s less, the more it grows.
b. I have always been led to understand that Phytoplankton is so named because it needs light to live and multiply. What mechanism does the Professor propose the light dependant plankton use to live and multiply in the dark and cold?
2.) ‘Zooplankton find their prey more easily as the concentration of phytoplankton rises.’
a.) Yet again I cannot follow his logic: if the zooplankton find the phytoplankton more easily and devour them with speed, how come the phytoplankton increase so fast?
But there was a consensus. The consensus is correct surely!!!
So if phytoplankton are the base of the oceanic food chain and they don’t do well in warm water then how does the good professor explain how the Gulf of Mexico is one of most productive fisheries in the world? Non sequitur.
I am embarrassed to say it but this is my field.
Whens zoos are abundant, it’s because their food is abundant, not the other way around.
They obviously need to get new books, they are reading Chemical Oceanography by Frank Millero. That book is an embarrassment to everyone in this field and people that do not know any better claim it’s the bible.
This is just another re-hash of the same old ‘currents are going to stop’ BS. One week global warming makes more storms, and the next week global warming makes less storms.
No wonder people are getting sick and tired of this.
According to the IPCC
What a croc!!!
Latitude,
yes. I’m sick of all this.
“I’m skeptical of the claim made about GW “stratifying the oceans, resulting in less mixing” because as we’ve been told many times, A Warming World Means More Destructive Storms. ”
I don’t know much about how TCs start up. But I don’t immediately see why a more stratified ocean means less destructive storms, as Watts seems to be implying here. Spell it out a bit?
REPLY: I recalled this story for example: http://www.nasa.gov/vision/earth/lookingatearth/giovanni.html
“Strong cyclonic surface winds of hurricanes are known to mix ocean surface waters, a process which brings nutrients and dissolved organic matter (carbon-based material created by biological activity in the oceans) to the sea surface from the lower depths of the ocean. With enough sunlight and the right temperatures and nutrients, phytoplankton, or free-floating unicellular aquatic algae, can grow quickly after a hurricane passes.”
Not just there. subtropical cyclone tracks often end up at higher latitudes where they dissipate. So they stir water over a long track, and currents further disperse. – Anthony
I start to feel like a boxer slugged groggy with misinformation, halftruths, assumptions, selfcontradictory theories, proof that proves proof isn’t proof.
All what is clear: No prediction made about AGW has come to fruition. We are now in the ‘wait for it’ holding pattern. It doesn’t happen now, but oh boy it will and when it does…..
I guess i’ll live out my remaining years in about the same climate i’ve been living in since birth. And then, apres moi la deluge.
In the mean time polar ice is not “Dropping.Like.A.Rock”;
http://www.ijis.iarc.uaf.edu/seaice/extent/AMSRE_Sea_Ice_Extent_L.png
Even assuming that the “CO2 with water vapor feedback” global warming is taking place in the atmosphere, i doubt that this will have much effect on ocean temperatures. LWIR doesn’t penetrate water; we don’t use hairdryers to cook water and we don’t use fans to cool water. The density of air is too low to warm or cool big amounts of water. The oceans can only get their heat from visible sunlight. So why should a GHG effect have any measurable effect on the oceans? Is there any paper trail by the AGW scientists that shows a link? Do they automatically assume that slightly higher global atmospheric temperature averages have any impact on oceanic temperatures or is that a consequence of GCM’s ? And even if the oceans were getting warmer, does this automatically lead to more “stratification”? Can that be observed in warmer parts of the oceans?
“Behrenfeld said that oceans are very complex, water mixing and currents can be affected by various forces, and more research and observation will be needed to fully understand potential future impacts.”
Yes, of course. More funding is needed. Why didn’t they say so in the first place, and skip all that other nonsense?
carrot eater:
No, you’re inferring that. What is implied is that this “stratification” of the ocean can’t take place if there are more intense storms. More storms means more mixing, not less. If warming causes more storms then it cannot also cause more stratification.
I am amazed at th authors not seeing the lack of logic in two statements, the first of which is:
“As winter storms become more frequent and intense, the biologically-rich surface layer mixes with cold, almost clear and lifeless water from deeper levels.”
Then a bit later, is this:
” . . because with further global warming, many ocean regions are expected to become warmer and more stratified.”
OK, if winter storms are to become more frequent and intense, resulting in deeper mixing, then how is the ocean to become more stratified, assuming both are from global warming? Ya can’t have it both ways . . .
“So, which is it? AGW means more storms? Less storms? A storm free Arctic?”
Probably whichever validates their meme this week.
I found this article to be very interesting.
Oh dear, a theory that was accepted by 100% of the discipline for over 50 years has turned out to be wrong. There must have been at least one blacklisted oceanographer in the 1950s who disagreed with the consensus – Hey you oceanographers must know who he/she was – make a good post.
Re the progression of global warming, check out DMI -temps above 80 degrees N appear to be plunging a month and a half early – its going to be a cold winter (Steve G take note):
http://ocean.dmi.dk/arctic/meant80n.uk.php
Oh and annoyingly, the color-coded temp map of intelliweather is miscolored again. It shows Toronto cool at 86F and Atlanta hot at 84F:
http://www.intelliweather.net/imagery/intelliweather/tempcity_nat_640x480.jpg
Nick Luke, I too am not a PhD, but I think I can explain what was said:
1. The winter storms mix “lifeless” cold water from below to the top.
2. The top water now is relatively spread out with regard to zoo and phyto plankton.
3. Spread out, the zoo can’t find the phyto as easily, so the phyto can grow while being eaten more slowly, and there’s a bloom.
4. The bloom makes it easier for the zoo to locate phyto, and they do, crashing the bloom.
OK, I’m only an Engineer.
But wouldn’t the good professor have made his thesis a little clearer if his nice North Atlantic ocean view used the cool colours for more phytoplankton and the warm colours for less phytoplankton?
But perhaps he swiped the illustration from a paper showing the previous hypothesis?
Worse than we thought! (academia).
I’m not expert on this subject, far from it.
It does make sense to me that phytoplankon can bloom in February and March — sure, it’s darker, but there’s still considerable available light, and the proof seems to be that the phytoplankton actually do grow at that time.
But it doesn’t make intuitive sense to me that increased mixing means that zooplankton can’t find their prey. Plankton can travel considerable distances. In parts of the Pacific, I’ve read, plankton come near the surface by day and sink several hundred feet at night, on a diurnal basis. But perhaps zooplankton aren’t as active in the coldest weather. Many plants and animals as a survival strategy breed or emerge when predators aren’t yet abundant, so that could be happening.
Why do the blooms fade out? Nutrient depletion seems to be key, because the phytoplanton keep on blooming in the spring, when the zooplankton graze on them. And the lack of vertical mixing may be key to the fading of the blooms.
The North Atlantic is quite different from the Southern Ocean. Down there, you NEED mixing to bring iron up to the surface, to create a plankton bloom, because iron is the limiting nutrient. But it appears from this Science Daily article that perhaps nutrient limitation due to lack of mixing occurs in the North Atlantic as well:
http://www.sciencedaily.com/releases/2009/07/090707111711.htm
So will we see less vertical mixing in the future, in a slightly to somewhat warmer world?
There are a couple of parts to this argument (at least).
One is that the North Atlantic will become less stormy. Tropical storminess and storminess in the North Atlantic have different origins, I would think, so it wouldn’t make sense to make a parallel with tropical cyclones in a warmer world. If the world is 1 to 2 degrees warmer, F, on average, will the North Atlantic be less stormy? I don’t know the reasoning for why it would be, I’m just unknowledgeable, other than to say that it doesn’t have much to do with hurricane formation and intensity.
Another part is to ask whether there was both increased stratification AND less nutrient availability when the earth was much warmer. The Eocene, when crocodiles and were near the north pole, would be a good test case.
Latitude, can you tell us anything about stratification and nutrient availability in the Eocene? Anyone else?
kwik says:
July 17, 2010 at 10:44 am
“In the mean time polar ice is not “Dropping.Like.A.Rock”;
http://www.ijis.iarc.uaf.edu/seaice/extent/AMSRE_Sea_Ice_Extent_L.png ”
Right, and I am waiting for a media-headline to announce: “July 2010 rate of reduction of sea-ice extent slowest since satellite records began”.
However, no-one should be holding his breath waiting for that to happen.
Archonix,
Thank you. I suppose I took the cause-and-effect intended in Anthony’s statement exactly backwards, and thus I was confused.
Though I don’t think there’s an inconsistency there. Climate change can bring about changes in the thermocline, even if individual storms brings some mixing between surface and the deeper waters. How long do you expect such effects from a single storm to last, after all?
It’s plausible to think that preditor and prey abundances as well as limiting physical factors (light and nutrients) are important regulating factors of plankton blooms. In fact, it’s not a very new idea at all. But when the global warming *IF* gets tacked on, ecological science drifts off into the realm of psychic speculation.
So sad; once again good science polluted with a forced AGW tie-in. The paper was really good until the end. The nice thing about this theory, is that it is testable.