In How We Wrecked The Oceans — Part II, I reported on a result published in the science journal Nature. It was reported that phytoplankton in the oceans has declined 40% since 1950. In so far as this is easily the most terrifying thing I've ever read concerning the human impact on the natural world, I thought I would post an update today. I've now had a chance to read the published paper, which is now available on the web.
The identified culprit is sea surface temperature (SST), which has risen due to anthropogenic climate change (i.e. global warming arising from the burning of fossil fuels).
Physical drivers of phytoplankton trends
Long-term trends in phytoplankton could be linked to changes in vertical stratification and upwelling, aerosol deposition, ice, wind and cloud formation, coastal runoff, ocean circulation or trophic effects. For parsimony, we focus on three variables that may reflect the coupling between physical climate variability and the Chl concentration in the upper ocean: ocean MLD (1955–2009), wind intensity at 10m (1958–2009) and SST (1899–2009)...
SST was the strongest single predictor of Chl. Rising SSTs overmost of the global ocean (Fig. 6a) were associated with declining Chl in eight out of the ten regions...
The effects of SST on Chl are probably explained by its influence on water column stability and MLD. Increasing SST leads to a shallower mixed layer, which further limits nutrient supply to phytoplankton in already stratified tropical waters, but may benefit phytoplankton at higher latitudes where growth is constrained by light availability and deep mixing. Indeed, in our local models MLD was a significant, but weaker, predictor of Chl concentrations compared with SST, possibly owing to the reduced time series span (1955–2009).
[My note: "Phytoplankton biomass is commonly inferred from measures of total chlorophyll pigment concentration (‘Chl’). AsChl explains much of the variance in marine primary production14 and captures firstorder changes in phytoplankton biomass, it is considered a reliable indicator of both phytoplankton production and biomass." MLD stands for "mixed layer depths" in the oceans.]
a. Estimated SST change at 1u resolution from 1899 to 2009. Blue represents cells where SST has declined while yellow and red represent increases. b, Effects of SST changes on Chl estimated for each 10u310u cell with .10 yr of data (n5205). Size of circles represents the magnitude and colours depict the sign of the standardized SST effect on Chl in each cell.
You are forgiven for not understanding everything you just read. The key passage is underlined. There was a follow-up article called Century of phytoplankton change by David A. Siegel and Bryan A. Franz—
Boyce et al. make a sorely needed contribution to our knowledge of historical changes in the ocean biosphere. Their identification of a connection between long-term global declines in phytoplankton biomass and increasing ocean temperatures does not portend well for pelagic ecosystems in a world that is likely to be warmer — phytoplankton productivity is the base of the food web, and all life in the sea depends on it. Unfortunately, owing to the costs and complexity of satellite ocean-colour systems and competing priorities for science funding, our future ability to assess these changes is also in jeopardy.
In the United States, a National Research Council study is under way to assess issues concerning sustained satellite ocean-colour observations. Improving the long-term understanding of changes in pelagic ecosystems, initiated by Boyce et al., will depend on the resolution of these issues.
What you don't see is often more important than what you do see. What we don't see here or any place else is serious criticism of the methodology used or otherwise serious questioning of the results. Thus the preliminary finding stands subject to further confirming or disconfirming research. That research should tell us whether this scary trend is continuing. That is to say, we might see a continuing loss of phytoplankton in the oceans at a rate of 1% per year.
The question of why we have not witnessed any dire effects of such a large, detrimental change in the oceans remains unanswered. Spiegel Online's A Food Chain Crisis in the World's Oceans quotes Boris Worm, one the study's authors, and some other scientists—
"We had suspected this for a long time," Boris Worm, the author of the study for Dalhousie University in Halifax, Canada, told SPIEGEL ONLINE. "But these figures still surprised us." At this point, he said, one can only speculate as to what the repercussions might be."
In principal, though, we should assume that such a massive decline is already having tangible consequences," said Worm. He said that the lack of research on the food chain between phytoplankton and larger fish in the open ocean is a hindrance to knowing the extent of the damage.
In other words, it could be that humans have not yet been affected. But Worm fears that will not remain the case for long. If the trend continues and the phytoplankton mass continues to shrink at a rate of 1 percent per year, the "entire food chain will contract," he predicts...
Other experts have also said they were struck by the sheer scale of the development. "A retreat of 40 percent in 60 years, that is so serious that it is almost unbelievable," says Heinz-Dieter Franke of the Biological Institute Helgoland, part of the Alfred Wegener Institute for Polar and Marine Research.
He warned, however, against attributing the decline in phytoplankton solely to temperature increases. Higher temperatures, after all, could also result in more nutrients being delivered by air, he said. Other influences, like changes in cloud composition — and thus changes in sunlight on the oceans' surface — complicate the situation.
Other factors may complicate this "unbelievable" situation ... making it even worse than now thought. Assuming the current trend continues, and that the annual depletion does not accelerate, how bad is this loss of phytoplankton in the oceans? Some Assembly Required reports this quote by "peak oil" advocate prophet Robert Hirsch. Here's the original interview. I think this quote puts things in persective.
Dr. Robert Hirsch, a man with excellent oil & energy credentials and author of a 2005 DOE report on peak oil, says there was “a conspiracy to keep it (peak oil) quiet” in Washington, but that “if you’re a reasonably intelligent person, you see that catastrophic things are going to happen to the world. We’re talking about major damage, major change in our civilization. Chaos, economic disaster, wars, all kinds of things that are, as I say, very complicated, non-linear. Really bad things.”
My view is that some catastrophic things have already happened in the world. And I happen to know a thing or two about peak oil, having written a weekly column for ASPO-USA on & off for about 3 years. I don't see peak oil causing chaos, economic disaster, wars and all kinds of things for many years to come, depending on how events play out. I do think we're going to have another oil price shock, but I'm not sure when. I'm still waiting to see if there's going to be a global economic depression—the outcome in China is still uncertain.
On the other hand, perhaps the phytoplankton loss in the oceans will be 50% or more (since 1950) by the time shortfalls in the global oil supply cause what Hirsh regards as a total human disaster. If that were the case, we would be well on the way toward an uninhabitable planet some centuries or millennia down the line.
Now, that's what I call a disaster.