Borrowing a phrase from NSIDC’s Dr. Mark Serreze, Phytoplankton are now apparently in a “Death Spiral”. See Death spiral of the oceans and the original press release about an article in Nature from a PhD candidate at Dalhousie University, which started all this. I’m a bit skeptical of the method which they describe in the PR here:
A simple tool known as a Secchi disk as been used by scientists since 1899 to determine the transparency of the world’s oceans. The Secchi disk is a round disk, about the size of a dinner plate, marked with a black and white alternating pattern. It’s attached to a long string of rope which researchers slowly lower into the water. The depth at which the pattern is no longer visible is recorded and scientists use the data to determine the amount of algae present in the water.
Hmmm. A Secchi disk is a proxy, not a direct measurement of phytoplankton. It measures turbidity, which can be due to quite a number of factors, including but not limited to Phytoplankton. While they claim to also do chlorophyll measurements, the accuracy of a SD measurements made by thousands of observers is the central question.
From the literature: The Secchi disk transparency measurement is perhaps one of the oldest and simplest of all measurements. But there is grave danger of errors in such measurements where a water telescope is not utilized, as well as in the presence of water color and inorganic turbidity (source: Vollenweider and Kerekes, 1982). I’ll have more on this later. – Anthony
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Phytoplankton need cap and trade
By Steve Goddard
Yesterday, Joe Romm reported :
Nature Stunner: “Global warming blamed for 40% decline in the ocean’s phytoplankton”
“Microscopic life crucial to the marine food chain is dying out. The consequences could be catastrophic.”
That sounds scary. Does it make any sense? Phytoplankton thrive everywhere on the planet from the Arctic to the tropics. One of the primary goals of this year’s Catlin expedition was to study the effect of increased CO2 on phytoplankton in the Arctic. They reported:
Uptake of CO2 by phytoplankton increases as ocean acidity increases
That sounds like good news for Joe! We also know that phytoplankton have been around for billions of years, surviving average global temperatures 10C higher and CO2 levels 20X higher than the present.
http://ff.org/centers/csspp/library/co2weekly/2005-08-18/dioxide.htm
Phytoplankton growth/reduction in the tropics correlates closely with ENSO. El Nñio causes populations to reduce, and La Niña causes the populations to increase.
During an El Niño year, warm waters from the Western Pacific Ocean spread out over much of the basin as upwelling subsides in the Eastern Pacific Ocean. Upwelling brings cool, nutrient-rich water from the deep ocean up to the surface. So, when upwelling weakens, phytoplankton do not get enough nutrients to maintain their growth. As a result, surface waters turn into “marine deserts” with unusually low populations of phytoplankton and other tiny organisms. With less food, fish cannot survive in the surface water, which then also deprives seabirds of food.
During La Niña conditions, the opposite effect occurs as the easterly trade winds pick up and upwelling intensifies, bringing nutrients to the surface waters, which fuels phytoplankton growth. Sometimes, the growth can take place quickly, developing into what scientists call phytoplankton “blooms.”
The phytoplankton must be loving life now!
The author of this study (Boris Worm) also reported last year “if fishing continued at the same rate, all the world’s seafood stocks would collapse by 2048”
So we know that phytoplankton have survived for billions of years in a vast range of climates, temperatures and CO2 levels. Apparently they have become very sensitive of late – perhaps from all the estrogens being dumped in the oceans? Or maybe they have been watching too much Oprah?
The standard cure for hyperventilation is to increase your CO2 levels by putting a bag over your head.
899
There are thousands of routine oceanography studies that examine water chemistry at different places, oceans and depths. A 40% change in water clarity and phytoplankton chlorophyll should also show readily measured changes in chemistry, such as total, dissolved and particulate nitrogen. Of course it would be a big job to compile the available data and such data are not as comprehensive as Secchi data.
Grumpy Old Man says:
July 31, 2010 at 9:32 am
Comments have been made relating to the use of the Secchi disc referring to its size, the number of tests and the size of the oceans. Statistically, the size of the population does not matter (in this case the area of ocean). What counts is that randomness of samples and the quality of samples
Grumpy:
I’ve been involved in work at a lake laboratory where we invited people from the region to come in and estimate the Secchi depth at a lab open house. Few of the values were 10% from the mean. Since seasonal variation in the lake ranged from about 2-20 meters, the variation, even among inexperienced users is negligible. The Secchi disk is a very nice instrument for estimating water transparency. You don’t need to worry about calibration or batteries.
I guess that the water is pretty turbid in the Gulf right now. Does that mean that the phytoplankton have migrated?
John:
You wrote: “Yet the polar regions are among the areas with considerably less phytoplankton growth. My BS meter was ringing loudly.”
I finished reading the paper. The researches are puzzled by this issue too! Here it what they wrote.
“Cumulatively, these findings suggest that warming SST and reduced MLD [mixed layer depths] may be responsible for phytoplankton declines at low latitudes. This mechanism, however, does not explain observed phytoplankton declines in polar areas, where ocean warming would be predicted to enhance Chl [chlorophyll pigment concentration] (Fig. 6c). This may partially be explained by concurrent increases in MLD and wind intensity there (see Supplementary Fig. 9). Further work is needed to understand the complex oceanographic drivers of phytoplankton trends in polar waters.”
So this is an open question.
“Cumulatively, these findings suggest that warming SST and reduced MLD [mixed layer depths] may be responsible for phytoplankton declines at low latitudes. This mechanism, however, does not explain observed phytoplankton declines in polar areas, where ocean warming would be predicted to enhance Chl [chlorophyll pigment concentration] (Fig. 6c). This may partially be explained by concurrent increases in MLD and wind intensity there (see Supplementary Fig. 9). Further work is needed to understand the complex oceanographic drivers of phytoplankton trends in polar waters.”
Maybe a very interesting paper but how are such “results” portrayed by the MSM and the propaganda team behind them? Are the bold-ed caveats mention…uh no. So the shrill bloggers and posters braying “denialism” and “conspiracy” theorist at any mention of skepticism are fed by this machine. Its all rather pathetic.
To Mike at 12:17 pm:
Thanks for letting me know that the researchers recognized the conundrum. I haven’t been able to get the full paper behind the firewall.
Do you have an opinion on the overfishing hypothesis put forward by Carl-Gustaf Lundin, head of the marine programme at the International Union for the Conservation of Nature (IUCN)? We certainly know about overfishing, they hypothesis rings true to me, so I’m wondering if you agree with it, or if you can think of a reason for why it might not be an adequate explanation?
John,
I do not have an opinion on the over fishing hypothesis. It was not discussed in the paper. We will have to wait and see what future research finds.
Jaye,
The mainstream media articles I posted links to did not seem terribly alarmist. Some of them interviewed researchers who had questions. Neither the NYT nor Wash Post has covered this. I think they should. It is important to separate criticism of the media and criticism of science. Both are fair game for public scrutiny, but they are different animals.
BillD – from the tsunami of mainstream articles that were marched out in goose-step on the 29th of July:
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The study has its drawbacks. The older shipboard data weren’t collected with nearly as much regularity as the satellite data, notes marine biologist Mike Behrenfeld of Oregon State University, Corvallis. Still, marine biologist David Siegel of the University of California, Santa Barbara, says that given the sporadic records, Worm and colleagues have constructed a solid report. “They’ve squeezed as much as possibly can be squeezed out of this data set.”
sciencemag, July 29
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They’ve squeezed it alright.
SeaWiFS, on the other hand, measures actual chlorophyll density globally, not the muddiness of water here and there, so the data requires no squeezing. By ignoring the two SeaWiFS studies mentioned above showing an increase in phytoplankton growth, rather than a decline, you don’t even have to bother with “dismissing the science.”
Here are those studies again:
http://www.nasa.gov/centers/goddard/news/topstory/chlorophyll.html
http://www.nasa.gov/vision/earth/environment/hurricane_bloom.html
Thankyou, Ulric, for the first one.
The article says:
“The scientific consensus is that we could not stop global warming at this point, even if we ceased all greenhouse gas production immediately. We have borrowed deeply against our environment and will be paying it back with interest for centuries.”
Well, problem solved!
Seriously, this is a highly flawed study. I’d never use something as primitive as a Secchi disc for this type of research…..modern biota enumeration utilizes extensive sampling, species identification, population assessments, even satellite analysis for large tracts of water.
Pollution from air deposition (toxics from Asia particularly), runoff from land, and building levels of recalcitrant levels of organic compounds including long-lived plastics are at least as likely for any phytoplankton decrease as warming. Until I see better science out of this bunch, I’m going to party like it’s 1999!
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Writes CRS:
“Seriously, this is a highly flawed study. I’d never use something as primitive as a Secchi disc for this type of research…..modern biota enumeration utilizes extensive sampling, species identification, population assessments, even satellite analysis for large tracts of water.”
Those who have subscriptions to Nature (or who are willing to cough up the cash to get through the paywall) have already offered information on this thread to the effect that it was not only Secchi disk observations that were conducted in the reported study, but apparently also a number of such other measurements (counts, species identifications, chemical analyses, temperature readings, etc.) as would occur to any undergraduate student in the average marine biology course who might get his hands upon – or construct, as we did when I was an undergraduate in a marine biology course – a Niskin bottle and dunk it into the water alongside the Secchi disk.
What they apparently did not do was to take into account two recent Sea-viewing Wide Field-of-view Sensor (SeaWiFS) studies which seem to have shown an increase in phytoplankton growth.
If our Dalhousie PhD candidate has not integrated the SeaWiFS information in his literature search – indeed, if the peer review officers of Nature did not exercise what I would personally consider due diligence in familiarizing themselves with such significant publications in the discipline and guide this young person toward them – the results attained in this article and the conclusions drawn thereupon are weaker than they really ought to be. Not so?
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Moderator, please note that posts on this thread seem at some point to have been HTML’d into default boldface. Can this be corrected? Thank you.
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REPLY: Fixed, Anthony
stevengoddard asked me:
“Do you have any evidence that there has been a “major shift” in temperatures? Even Hansen’s bloated numbers only show 0.65 degrees since 1880. By contrast, ENSO temperatures have changed ten degrees in less than a year.”
Note that I said “temperature and nutrient supply”. I should have said “temperature and/or nutrient supply”. Increasing eutrophication has caused many species shifts. So also has weather shifts, changing wind intensity, both for the Arabian Sea and Southern Ocean (the latter mentioned here in a previous comment). Not sure about other places that have a weather-ocean connection. Temperature stratification is enhanced in warmer waters, even slightly warmer, due to amplfication of density difference effects — as little as a 0.2 C shift in the temperature of a water mass can significantly alter its buoyancy. That’s been stated as a cause for a decades-long shift off Southern California. Curry et al. 2003 noted increasing salinity in tropical waters due to increased evaporaton; sorry that I don’t know how much of an ocean temperatre shift is required to drive that significantly. Not sure where Hansen fits into this, his data is global surface and temperature effects in the ocean are from surface to depth. Barnett et al. 2005 discussed ocean warming and Levitus et al. in 2000 and 2005 did too. The more recent Levitus et al. paper, which I found online, notes that ocean warming isn’t uniform, with regional diffrences due to shifts in atmospheric and oceanic circulation patterns or both.
Sorry I cant directly answer your question.
Khwarizmi says:
July 31, 2010 at 9:30 pm
BillD – from the tsunami of mainstream articles that were marched out in goose-step on the 29th of July:
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The study has its drawbacks.
Kwarizimi and others:
Of course this study and the use of the Secchi disk has draw backs. Unfortunately, over a hundred years ago, no one did comprehensive studies of the world’s oceans using modern instruments.
I have published a couple of articles based on long term data, and it’s usually not perfect. The challenge that scientists face is to make the most of the available data. Most of my research is experimental, but I really enjoyed the challenge of finding relatively clear and convincing answers in imperfect long term data. Of course, long term data are especially important for testing hypotheses about climate change. The strength of this paper is that the authors realized that Secchi data are available over the last century and then finding, throuogh analysis, that these data show a convincing and coherent pattern.
Unfortunately, the satallite data do not go back to 1900. I find the authors’ evidence that the Secchi disk data and the satillite data are concruent convincing.
Note–this is not a modelling study. However, it would be very interesting to plug the results of this study into models of physical and biological oceanography.
@ur momisugly Rich Matarese says:
July 31, 2010 at 11:25 pm
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REPLY: Using a Secchi disk for a study of this kind is arcane! This is comparable to using pH paper to measure the (supposed) decline in ocean pH. I’m surprised a sober journal like Nature considered the paper at all.
Secchi disks are commonly used in freshwater limnology as a simple “shake & bake” estimation test, but I sure wouldn’t extrapolate the readings for Secchi disk in the oceans and extrapolate results to a hemisphere! One good walrus dump would skew the results!
At University of Illinois, my team is doing extensive research on freshwater phytoplankton (microalgae) using fluorescence at 680 nm to determine growth rate. Results to be published soon, we are doing some growth manipulation techniques that have barely been investigated before.
CRS, Dr.P.H. says:
August 1, 2010 at 3:45 pm
@ur momisugly Rich Matarese says:
July 31, 2010 at 11:25 pm
Dr. P.H.
The whole point of this paper is having data collected over the last 100 years. I just don’t understand how your fluometer can be used to estimate conditions at the beginning of the 20th century. For data over the last few decades, satellite data on surface chlorophyll is cleary the best approach for ocean wide estimates.
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CRS, Dr.P.H. and BillD make good argument about how the “whole point of this [research work, which was to deal with] data collected over the last 100 years.”
Because satellite data has only been collected “over the last few decades,” it is not appropriate to compare information gained thereby with what had been obtained by observations conducted in the first decade of the 20th Century.
Such methods as Secchi disk observation were available to the researchers working a hundred years ago, and are easy enough to replicate today. So are certain straightforward chemical, physical, and microscopic analyses of water samples taken at various depths, which I understand were also conducted by the investigators publishing this report.
Were I convinced that the expenditure of cash and effort were worthwhile – remember, my training in marine biology is limited to one undergraduate course in which I was enrolled during the Nixon Administration, and this is way to hellangone outside my professional discipline – I’d get my hands on this paper in Nature if only to determine whether or not the authors had gone into any detail on the extent to which they’d taken pains to place their own reported observations into proper context against those of their predecessors.
Fortunately, we have in this forum the participation of people who are more proximally interested in (and experienced in) limnology and other aspects of marine biology, and some of them have got versions of this paper and its supporting data in hand.
As prior posts on this thread seem to indicate, the investigators’ findings and conclusions in this report appear to be presenting exaggerated claims of phytoplankton population attenuation to an extent which, on the face of things, draws immediately and unavoidably into doubt the validity of their methodologies and their interpretations of data obtained.
BillD avers that “The strength of this paper is that the authors realized that Secchi disk data are available over the last century and then finding, through analysis, that these data show a convincing and coherent pattern,” but as CRS correctly observes (“One good walrus dump would skew the results!” – and my own limited personal experience confirms – Secchi disk estimations of water turbidity are so damnably subject to situational variations having nothing to do with phytoplankton population densities that to speak of “a convincing and coherent pattern” may well be to invest wishful thinking in correlations which have nothing to do with the factors which one thinks are being studied.
Now, given that we do have observational data collected by way of more discriminatory methods (notably the SeaWiFS system, which “measures actual chlorophyll density globally, not the muddiness of water here and there, so the data requires no squeezing“), has there been any effort to correlate these findings against those gained in the contemporaneous performance of such relic techniques as Secchi disk evaluations of oceanic water turbidity?
That would set things in better context, would it not?
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Well I was recently asked by a Trout Expert to explain Secchi Disk anomalies (hate that word) that he had observed in making water turbidity measurments.
The SD is routinely used by water engineers who want to check the quality of fresh water lakes and reservoirs etc.
This trout Scientist spends a lot of time under water studying what trout actually do under water; their feeding behavior and such like; and he has become somewhat of an officionado of the Secchi Disk as a result.
He told me that he would routinely do SD measurements from his boat in lakes and other places; to see if it was worth jumping in to study trout behavior.
What he found was that when he was sitting on the bottom; looking at the trout; the visibility was nowhere near as good as his Secchi disk readings had indicated; and he was at a loss to understand why.
I suggested he take his Secchi disk down with him; and set it up over where his trout were and see if he got the same readings as he got from the boat.
Turns out he had already done exactly that; and no the readings were quite different. So he was bamboozled and asked me to explain it.
The Secchi disk operates by reflecting light from the white sectors back to the viwer; normally looking straghit down on the disk, as it is lowered into the water.
Turbidity scatters the light so some of it moves over so it appears to come from the black sectors of the disk; where no reflected light should be. Sop the white sectors get dimmer than they should be; and the black sectors get brighter than they should be; and ultimately the contrast disappears altogether.
It’s a bloody clever gizmo, since the radial sectors sweep out a range of spatial frequencies from center of the disk to the edge; so the center contrast vanishes first.
Well the observations are based on the presumption, that ambient light shines down on top of the disk or passes beyond the rim of the disk into a black hole; never to return.
When he set his disk up horizontally; it had a backdrop of independently illuminated water; so it was in a bright field rather than a dark field.
Now light from the bright field background comes by the edges of the dark segments; and scatters onto those segments as well as the other segments; and washes out the pattern much quicker that the strictly reflected dark field situation.
So the visibility really is much worse when looking hoirizontally into a bright field illuminated situation in a turbid medium.
He’s happy now that he knows it’s real.
I guess I should have added that likewise in the ocean; unless the water is really deep so it is a true dark field situation; then the Secchi disk is going to give wrong answers also.