Mass Extinction #6

One of these days I should go back and take a look at the details of the first 5 mass extinctions. The last one was 65 million years ago, and the evidence for it being caused by a large impactor is pretty solid. The other ones are less clear, as far as I know. The sixth one is currently underway, and the cause is pretty clear. Joe Romm has a nice post about it [LINK]. Whenever reading Romm, one must remember that he's always presenting the worst case scenario (and as if it is inevitable), but even when one scales his arguments by 50% or so, it's not a pleasant picture. If anyone wants to skip the commentary and read the source material, it is a special issue of Phil. Trans. [LINK].

The Whale Pump

It's this kind of shit that makes oceanography so hard... whale shit, literally. A new study suggests (and does not prove) [LINK][PLoS], that whale poop might pump nitrogen up to the surface in some areas of the oceans, acting as a boost to biological productivity (and consequently fish population). If this "whale pump" were eventually shown to be important in the global nitrogen cycle, how would climate models cope with that information? Who's going to code the whale_poop.F90 module? Geez.

Why make a point when you can just sound like you are?

Just read an article on Reuters with the headline: Whale poo helps offset carbon footprint. Sometimes articles get stupid headlines because the person writing the article isn't in charge of making the headline, but this article actually says this in the text. It's real short, go read it. I doubt you'll be as angered by it as I am, but maybe you'll see how incredibly stupid it is.

The story reports on science, which says that sperm whales in the Southern Ocean defecate in the upper ocean where phytoplankton use the iron from the feces to grow. This in turn, allows the phytoplankton to "absorb" more carbon. The idea is just like iron fertilization.

The point that they article makes is that the cycle actually reduces atmospheric CO2 because the amount of carbon used by the phytoplankton is twice as much as is breathed out by the whales. Thus, Michael Perry (the reporter) concludes, the whales offset their carbon and reduce their carbon footprint.

First off, whales don't have feet, so they have no footprint.

Second, though, whales also don't use fossil fuels, so whales have no carbon footprint.

The science sounds interesting enough, and it seems like they are showing that this aspect of the carbon cycle is a net sink of atmospheric carbon. One caveat that isn't dealt with is that the phytoplankton don't necessarily use the carbon immediately die and sink, there is also a lot of recycling in the upper ocean. So this "carbon sequestration" (which just means that the phytoplankton die and sink to the deep ocean) might not be as strong as this news article would lead us to believe.

A larger point is that in the absence of humans, this would just be one of many small carbon sinks that would balance a lot of carbon sources, closing the carbon cycle. Unperturbed ecosystems, much less individual species, are (over long time scales) in steady-state. Imagine that humans disappear, so all the anthropogenic CO2 stays around, but no more is added. These whales(+phytoplankton) might continue to act as a net carbon sink, but over the long run, they aren't going to suck all the carbon out of the atmosphere. Okay, I'll stop belaboring this point.

What makes this an even better example of lazy science reporting is that the really interesting point about the whales'(+phytoplankton's) role in the carbon cycle is buried in the last sentence:

Lavery said that without whaling there may have been 120,000 sperm whales in the Southern Ocean and, according to her calculations, some 2 million tonnes of carbon may have been removed from the atmosphere each year through this process.

So what this says is that if the whale population was what it should be, the carbon source would be ten times larger (there are currently ~12,000 sperm whales in the Southern Ocean). So the interesting twist, in my opinion, isn't that the whales are "carbon negative," but really that whaling represents an increase in atmospheric CO2 by reducing a natural sink. This is just like (though much smaller than) land-use change, which removes carbon-absorbing ecosystems with cropland, removing a terrestrial sink. Does this raise the question of whether over-fishing represents such a decrease in a natural sink? So instead of going off half-cocked to do geoengineering through iron fertilization [e.g.], we should make a legitimate attempt to allow the natural ocean ecosystems to recover from the past couple of centuries of abuse.

UPDATE:
An AP story also has most of this, but better covers the whaling angle: [LINK]

Marathon runners not a source of CO2 to atmosphere -- shocker!

I'm so glad that RSS exists, so that I don't miss stories like "Barton worries that EPA will regulate runners" from Kate Sheppard at Grist. Did you read it yet? Just in case you didn't, let me recap for you. Representative (from Texas) Joe Barton (Republican) is the ranking Republican on the Energy and Commerce Committee, which means he's the most senior Republican on the committee. This committee's role is, from Wikipedia:

The House Committee on Energy and Commerce has developed what is arguably the broadest (non-tax-oriented) jurisdiction of any Congressional committee. Today, it maintains principal responsibility for legislative oversight relating to telecommunications, consumer protection, food and drug safety, public health, air quality and environmental health, the supply and delivery of energy, and interstate and foreign commerce in general. This jurisdiction extends over five Cabinet-level departments and seven independent agencies--from the Energy Department, Health and Human Services, the Transportation Department to the Federal Trade Commission, Food and Drug Administration, and Federal Communications Commission — and sundry quasi-governmental organizations.

Which is to say, this is a pretty powerful committee. They get to advance (or squelch) a lot of potentially important legislation. And Barton, as ranking member, is a powerful guy within this powerful committee. So it matter that he thinks crazy things, like that marathon runners could be considered a source of pollution. Yeah, didn't you read that article? It goes back to the EPA's decision that carbon dioxide can be considered a pollutant, and as such can be regulated. Barton thinks that people are point sources of carbon dioxide, and I guess because marathons are a large group of heavily exhaling people, Joe thinks that means a large source of carbon dioxide to the atmosphere.

The point Barton is trying, and failing, to make is that carbon dioxide is difficult to regulate because it is a naturally occurring substance that is a basic part of all life on Earth. The reason he is trying to make this point is because he doesn't want to believe that the EPA has the right to regulate carbon dioxide. There are two reasons he doesn't want to accept that. First, because he's a Republican, and that party has decided to oppose regulation of nearly any kind. (Examples, regulating financial institutions like AIG or energy brokers like Enron.) Second, as part of Barton's ideology, he can't accept that humans affect the Earth adversely, so he emotionally reacts to climate change by denying it.

The point I want to make is that Barton is wrong about marathon runners. They aren't a source of carbon dioxide to the atmosphere, even though they do exhale carbon dioxide. The reason is that humans are part of the terrestrial biosphere, which is part of the global carbon cycle, which is basically in balance except for the perturbation from burning fossil fuels. To see this, think about that air you just exhaled, which is relatively enriched in carbon dioxide. Note, you don't breathe in pure oxygen, and you don't exhale pure carbon dioxide. How did that CO2 get into your breath? It is a byproduct of your physiology, mostly it come from breaking down sugars, which provides you with energy. So that means we're a source! No, wait a minute, where did those sugars come from? You ate them! This is exactly why we eat, to ingest the nutrients that will supply us with energy. So think about that for a second: we eat foods that have carbon in various organic molecules, which we break down to get energy, and CO2 is made as a byproduct and respired.

But that means humans (and all animals) make CO2 and put it into the air.

Yeah, but it all comes from somewhere. Let's take me as a simple example, or a cow. The point being, the cow and I are vegetarians, so most of the CO2 we respire comes from breaking down plant matter. Where does the carbon in that plant matter come from? Remember what we all learned as kids, plants breathe in CO2 and breathe out oxygen. Yes, plants take the CO2 right out of the air. They take CO2 from the air, water from the soil, and sunlight, and perform photosynthesis, which is to say 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. Like magic, isn't it. On the right side are just 6 molecules of oxygen along with a sugar molecule that is holding onto some carbon and oxygen, which I'll eat and break down for energy, releasing CO2. Magic.

So there's a balance... like a cycle of carbon in the biosphere. This is why, in principle, biofuels should be carbon neutral. Breaking down plant matter moves CO2 around, eventually expelling it into the atmosphere, but eventually it is sucked back into the biosphere by autotrophs like plants and phytoplankton.

So what's the problem with burning fossil fuels? Well, that takes carbon from the lithosphere and suddenly introduces it to the atmosphere-biosphere-ocean system. There is normally exchange between the lithosphere and the rest of the climate system, but that is a very slow process, which combustion accelerates. There's no where for that extra CO2 to go because each part of the cycle only has so much wiggle room. The result is a build-up of CO2 in the atmosphere, where it enhances the greenhouse effect, and chaos ensues. Carbon dioxide isn't a pollutant like CFCs, then, but the carbon dioxide emitted by burning fossil fuels is basically the same. Whatever oil, coal, or natural gas is pulled out of the rocks needs to be accounted for, because that is the potentially harmful carbon.