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Another False Alarm: The Phytoplankton Scare Debunked

I took a lot of flak last year for my post saying that the global 50% drop in phytoplankton claimed by Boyce et. al was an illusion. I had said:

So where did the Nature paper go wrong?

The short answer is that I don’t know … but I don’t believe their results. The paper is very detailed, in particular the Supplementary Online Information (SOI). It all seems well thought out and investigated … but I don’t believe their results. They have noted and discussed various sources of error. They have compared the use of Secchi disks as a proxy, and covered most of the ground clearly … and I still don’t believe their results.

In other words, I took my chances on my experience and went way, way out on a limb with my statements. And of course, people didn’t let me forget it.

Figure 1. Life Cycle of Phytoplankton

Now we get these two Brief Communications Arising, from Nature magazine (emphasis mine).

Nature  Volume: 472, Pages:  E6–E7

Brief Communication Arising (April, 2011) Arising from D. G. Boyce, M. R. Lewis & B. Worm Nature 466, 591–596 (2010)

Phytoplankton account for approximately 50% of global primary production, form the trophic base of nearly all marine ecosystems, are fundamental in trophic energy transfer and have key roles in climate regulation, carbon sequestration and oxygen production. Boyce et al.1 compiled a chlorophyll index by combining in situ chlorophyll and Secchi disk depth measurements that spanned a more than 100-year time period and showed a decrease in marine phytoplankton biomass of approximately 1% of the global median per year over the past century. Eight decades of data on phytoplankton biomass collected in the North Atlantic by the Continuous Plankton Recorder (CPR) survey2, however, showan increase in an index of chlorophyll (Phytoplankton Colour Index) in both the Northeast and Northwest Atlantic basins 3, 4, 5, 6, 7 (Fig. 1), and other long-term time series, including the HawaiiOcean Time-series (HOT)8, the Bermuda Atlantic Time Series (BATS)8and the California Cooperative Oceanic Fisheries Investigations (CalCOFI)9 also indicate increased phytoplankton biomass over the last 20–50 years. These findings, which were not discussed by Boyce et al.1, are not in accordance with their conclusions and illustrate the importance of using consistent observations when estimating long-term trends.

Along with this one:

Nature 472, E5–E6 (14 April 2011)

Brief Communication Arising (April, 2011) Arising from D. G. Boyce, M. R. Lewis & B. Worm Nature 466, 591–596 (2010)

… Closer examination reveals that time-dependent changes in sampling methodology combined with a consistent bias in the relationship between in situ and transparency-derived chlorophyll (Chl) measurements generate a spurious trend in the synthesis of phytoplankton estimates used by Boyce et al.1. Our results indicate that much, if not all, of the century-long decline reported by Boyce et al. is attributable to this temporal sampling bias and not to a global decrease in phytoplankton biomass.

OK, so I was right. The Boyce paper was nonsense, the claimed trend was spurious, plankton biomass is holding somewhere near steady or even increasing, and a number of independent records show that the Boyce et al. paper is garbage built on bad assumptions.

I bring this up for three reasons. The first is to show the continuing shabby quality of peer-review at scientific magazines when the subject is even peripherally related to climate. Nature magazine blew it again, and unfortunately, these days that’s no news at all. It’s just more shonky science from the AGW crowd … and people claim the reason the public doesn’t trust climate scientists is a “communications problem”? It’s not. It’s a garbage science problem, and all the communications theory in the world won’t fix garbage science.

The second reason I posted this is just because I enjoy it when it turns out that I’m right, particularly on a risky statement made with no data and in the face of opposition, and I wanted to enter that fact into the record. Childish, I know, but at least I’m adult enough to admit it.

The third reason is a bit more complex. It is to emphasize the value of actual experience. I didn’t disbelieve Boyce et al. because I had any data. I had no data at all.

What I did have was a lifetime spent on and under the ocean. Phytoplankton form the basis of all life in the ocean. If the phytoplankton had actually gone down by 50%, all life in the ocean would have gone down by 50% … and my experience said no way that was true. Fish catches haven’t gone down like that, numbers of species on the reef and along the coast haven’t gone down like that, I would have noticed, people around the world would have been screaming about it.

So I put my neck on the chopping block, and I trusted my experience … and in the end, despite the people who laughed at me and abused my claims, my experience won out over Boyce’s “science”.

Does this mean that we should always trust our experience over science? Don’t be daft. Science is hugely valuable, and often shows that our experience has misled us completely.

But far too many scientists forget to check the obvious – their own experience. Not one of the Boyce authors thought “Wait a minute … since the oceans live almost entirely off the phytoplankton, if plankton is down by half why haven’t I seen oceanic populations from krill to whales and octopuses dropping by half?” Or perhaps they just didn’t have the experience to check the obvious.

The moral of this story? Well, the moral for me is that trusting my experience over the “science” of high-powered scientists living in an ivory tower far above the ocean worked out well … this time.

But the real moral is that scientists need to pay more attention to the “laugh test”. I know when I first heard the Boyce claim, I busted out laughing … and when our experience is that strong in saying that science is wrong, it’s likely worth checking out.

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