Phytoplankton Numbers Are Phalling

Lauren Morello at Scientific American:

The microscopic plants that form the foundation of the ocean’s food web are declining, reports a study published July 29 in Nature.

The tiny organisms, known as phytoplankton, also gobble up carbon dioxide to produce half the world’s oxygen output—equaling that of trees and plants on land.

But their numbers have dwindled since the dawn of the 20th century, with unknown consequences for ocean ecosystems and the planet’s carbon cycle.

Researchers at Canada’s Dalhousie University say the global population of phytoplankton has fallen about 40 percent since 1950. That translates to an annual drop of about 1 percent of the average plankton population between 1899 and 2008.

The scientists believe that rising sea surface temperatures are to blame.

Ed Yong at Discover:

Graduate student Daniel Boyce focused on some of oceans’ smallest but most important denizens – the phytoplankton. These tiny creatures are the basis of marine food webs, the foundations upon which these watery ecosystems are built. They produce around half of the Earth’s organic matter and much of its oxygen. And they are disappearing. With a set of data that stretches back 100 years, Boyce found that phytoplankton numbers have fallen by around 1% per year over the last century as the oceans have become warmer, and if anything, their decline is getting faster.  Our blue planet is becoming less green with every year.

Meanwhile, post-doc Derek Tittensor has taken a broader view, looking at the worldwide distributions of over 11,500 seagoing species in 13 groups, from mangroves and seagrasses, to sharks, squids, and corals. His super-census reveals three general trends – coastal species are concentrated around the western Pacific, while ocean-going ones are mostly found at temperate latitudes, in two wide bands on either side of the equator. And the only thing that affected the distribution of all of these groups was temperature.

Together, the results from the two studies hammer home a familiar message – warmer oceans will be very different places. Rising sea temperatures could “rearrange the global distribution of life in the ocean” and destabilise their food webs at their very root. None of this knowledge was easily won – it’s the result of decades of monitoring and data collection, resulting in millions of measurements.

Boyce’s study, for example, really began in 1865, when an Italian priest and astronomer called Father Pietro Angelo Secchi invented a device for measuring water clarity. His “Secchi disk” is fantastically simple – it’s a black-and-white circle that is lowered until the observer can’t see it any more. This depth reveals how transparent the water is, which is directly related to how much phytoplankton it contains. This simple method has been used since 1899. Boyce combined it with measurements of the pigment chlorophyll taken from research vessels, and satellite data from the last decade.

Boyce’s data revealed a very disturbing trend. Phytoplankton numbers have fallen across the world over the last century, particularly towards the poles and in the open oceans. The decline has accelerated in some places, and total numbers have fallen by around 40% since the 1950s. Only in a few places have phytoplankton populations risen. These include parts of the Indian Ocean and some coastal areas where industrial run-off fertilises the water, producing choking blooms of plankton.

On a yearly basis, the rise and fall of the phytoplankton depends on big climate events like the El Nino Southern Oscillation. But in the long-term, nothing predicted the numbers of phytoplankton better than the surface temperature of the seas. Phytoplankton need sunlight to grow, so they’re constrained to the upper layers of the ocean and depends on nutrients welling up from below. But warmer waters are less likely to mix in this way, which starves the phytoplankton and limits their growth.

Michael O’Hare:

What makes human life worth living? Content, obviously: news, art, music, conversation – social intercourse in all media.  What makes it possible?  Food and drink, broadly defined: fresh water and all the plant and animal products we eat and use.

This morning I came upon a paper in Nature whose abstract is as follows (emphasis added):

In the oceans, ubiquitous microscopic phototrophs (phytoplankton) account for approximately half the production of organic matter on Earth. Analyses of satellite-derived phytoplankton concentration (available since 1979) have suggested decadal-scale fluctuations linked to climate forcing, but the length of this record is insufficient to resolve longer-term trends. Here we combine available ocean transparency measurements and in situ chlorophyll observations to estimate the time dependence of phytoplankton biomass at local, regional and global scales since 1899.We observe declines in eight out of ten ocean regions, and estimate a global rate of decline of ~1% of the global median per year. Our analyses further reveal interannual to decadal phytoplankton fluctuations superimposed on long-term trends. These fluctuations are strongly correlated with basin-scale climate indices, whereas long-term declining trends are related to increasing sea surface temperatures. We conclude that global phytoplankton concentration has declined over the past century; this decline will need to be considered in future studies of marine ecosystems, geochemical cycling, ocean circulation and fisheries. (paywall)

This finding – and I’m trying hard not to hyperventilate here – is not too far down the scary scale from discovering a small inbound asteroid. This is the whole ocean we’re talking about: the earth’s production of organic material is going down half a percent per year.  Oddly, I did not come upon it in the New York Times, which seems not to have run the story at all.  The Washington Post, I found only after I searched, did run the AP story somewhere way below whatever passes for the fold in a web edition, but I didn’t see it there either.  I found it, through a Brazilian accumulator, here.

How can this be? Well, the world’s production of traditional news (not newsworthy events, writing about them) is down along with the plankton (and the menu items at your favorite seafood restaurant…remember when you could have haddock for dinner?).  Every grownup, quality-conscious outlet is putting out less stuff every day, in fewer column-inches on smaller pages (or in more vacuous hours on TV padded out with ephemera that a small crew in a truck can get some meaningless video of).  The new, lean, pathetic Times just didn’t have room for this one (or salary to pay an editor to stay on top of stuff), a story I can make a case was the most important news of the week (why the Globo happened to put it on page one is not clear (as did the São Paulo paper), but muito obrigado, a Sra. da Silva também!).  I guess I can stay informed if I go to six web pages in four languages every day, but who has time, and why is that better than the way things were before the content markets fell apart?  And how long will even that strategy work?

We can’t live without the ocean, every time we look at climate change it’s worse than we thought, and we can’t get back from the precipice, or even know how close it is, without news.

We are so f____ed.

Kevin Drum:

So, anyway, as temperatures rise the plankton die. As plankton die, they suck up less carbon dioxide, thus warming the earth further. Which causes more plankton to die. Rinse and repeat. Oh, and along the way, all the fish die too.

Or maybe not. But this sure seems like a risk that we should all be taking a whole lot more seriously than we are. Unfortunately, conservatives are busy pretending that misbehavior at East Anglia means that global warming is a hoax, the Chinese are too busy catching up with the Americans to take any of this seriously, and you and I are convinced that we can’t possibly afford a C-note increase in our electric bills as the price of taking action. As a result, maybe the oceans will die. Sorry about that, kids, but fixing it would have cost 2% of GDP and we decided you’d rather have that than have an ocean. You can thank us later.

Megan McArdle:

The die-off of most of the phytoplankton would be a huge catastrophe.  However, here are some reasons that we shouldn’t succumb to outright panic quite yet:

1.  It’s one paper.  I am not casting aspersions on the authors or their methodology, but the whole idea of science is that even the smartest people can be wrong.  As with other attempts to reconstruct past climate, they’re using a series of proxies for past events that have much weaker accuracy than the direct measurements we’re now using.  That doesn’t mean they’re wrong, but it does leave them more open to interpretation.

2.  All the carbon we’re burning used to be in the atmosphere.  Yet the planet supported life.  Indeed, the oil we’re burning comes from the compressed, decayed bodies of . . . phytoplankton.  This suggests that some number of phytoplankton should be able to survive high concentrations of the stuff.

3.  There are positive feedback effects, but also negative ones.  One of the things that drives me batty about environmentalists and journalists writing about climate change is the insistence that every single side effect will be negative. This is not really very likely, unless you think that every place on earth just happens to be at the very awesomest climate equilibrium possible as of 9:17 am this morning, or that global warming is some sort of malevolent god capable only of destruction.

Mind you, this is not an argument for letting it happen; I’m not a fan of tampering with large, complex systems that I don’t really understand, which is why I tend not to support much direct government intervention in the economy–and why I do, nonetheless, support a hefty carbon tax.

But there’s a certain tendency to ignore mitigating offsets, such as the fact that higher carbon concentrations make terrestrial plants grow more lushly, sucking up some of that extra carbon dioxide in the atmosphere.  At least, as long as we don’t turn them into biofuels, that is.  There’s also a tendency to ignore mitigation rather than reduction, on the grounds that emissions reduction is “easier”.  Well, I suppose it is easier if you assume away the political problems.  But no matter how hard I assume, I keep waking up in a world where we’ve made no meaningful progress on emissions reductions.  At this point, I’ve got more faith in America’s engineering talent than in her ability to conquer fierce political resistance to reductions at home and abroad.

Brad Plumer at TNR on McArdle:

She’s partly right. Not every side effect will be negative. Just this week, The New York Times ran a piece about how marmots will thrive in a hotter world. So, three cheers for marmots. But the bad news tends to far outweigh the good. As the IPCC concluded in 2007, “Costs and benefits of climate change for industry, settlement and society will vary widely by location and scale. In the aggregate, however, net effects will tend to be more negative the larger the change in climate.” No one’s ignoring the upsides. They’re just focused on the larger downsides. For instance, McArdle suggests that more CO2 in the air will boost plant growth, which in turn will help suck more carbon out of the air and ameliorate things somewhat. It might surprise her to learn that scientists are perfectly well aware of that fact. But recent modeling suggests that this effect will likely be offset by other plant-related factors—like changes in evaporation—and the net result will likely be more warming, not less.

One main point to note here is that, on the whole, global warming will be neutral for this round little rock adrift in the ether that we like to call Earth. You could even say this is an exciting time for Mother Nature. Big changes are afoot. Some species will thrive and many others will die. Evolution will proceed apace. There will still be some forms of life around even if the planet heats up by 5°C or 10°C. As McArdle rightly notes, there have been periods in the past, millions of years ago, when carbon concentrations in the atmosphere were even higher than today, and, to quote Jurassic Park, life found a way.

The problem here is for one very particular life form: people. As I wrote in this TNR piece on planetary boundaries, we big-brained hominids have enjoyed a relatively stable climate for the past 10,000 years—a geological period dubbed the Holocene. Sea levels have been kept in check. Temperatures have fluctuated around a narrow band. And that relative predictability has enabled us to stay rooted in one location, to set up farms and cities, to plan for the future. We’ve adapted very well to the planet we have, and we’ve grown quite used to it. Most of our infrastructure has been built under the impression that the planet will basically look the same tomorrow as it did yesterday. That means that wrenching shifts in our ecosystem run the risk of being extremely painful—in the same way a big disruption to our financial system was extremely painful.

The second problem is that we just don’t know what’s in store. By belching up millions of tons of greenhouse gases into the atmosphere, we’re running a massive science experiment on the planet, one that can’t really be reversed. Maybe this phytoplankton stuff is just a blip. Or maybe it’s part of an ominous trend that’s going to rearrange the face of the oceans as we know it—oceans we’ve come to rely on for our survival. That doesn’t strike me as a gamble worth taking.

About these ads

Leave a comment

Filed under Environment, Science

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s