One of the enduring themes of this site is that we risk making very costly errors if we over-compartmenalize our perceptions. This is why I so often argue against the idea that we can pick one of the Twin Terrors (climate chaos and peak oil) and say, “This is the one that really matters–the other one will take care of itself.” Those among my fellow greenies who think that “peak oil is a good thing because it will prevent us from emitting so much CO2″ are merely indulging in an ever so slightly more nuanced version of the basic “this matters a lot and I can ignore that” mindset.
Of course, we can’t literally consider all things at once; we have to, and naturally do, compartmentalize many issues. Which size memory card to buy for my camera has no connection with whether I choose to cut the grass today or let it go and risk being delayed by further rain (to cite two recent, real-world examples from my own life). Many decisions are much less clear, and sometimes we get surprises, when the universe tells us that, golly gee, the rate of CO2 uptake of the Southern Ocean is affected by the state of the ozone layer:
New Scientist: Ozone hole has unforeseen effect on ocean carbon sink:
The Southern Ocean has lost its appetite for carbon dioxide, and now it appears that the ozone hole could be to blame.
In theory, oceans should absorb more CO2 as levels of the gas in the atmosphere rise. Measurements show that this is happening in most ocean regions, but strangely not in the Southern Ocean, where carbon absorption has flattened off. Climate models fail to reproduce this puzzling pattern.
The Southern Ocean is a major carbon sink, guzzling around 15 per cent of CO2 emissions. However, between 1987 and 2004, carbon uptake in the region was reduced by nearly 2.5 billion tonnes – equivalent to the amount of carbon that all the world’s oceans absorb in one year.
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The effect could be down to the way decreasing stratospheric ozone and rising greenhouse gases are altering the radiation balance of the Earth’s atmosphere. This has been predicted to alter and strengthen the westerly winds that blow over the Southern Ocean.
“We expected this transition to a windier regime, but it has occurred much earlier than we thought, seemingly because of the ozone hole,” says Lenton.
Stronger surface winds enhance circulation of ocean waters, encouraging carbon-rich waters to rise from the deep, limiting the capability of surface water to absorb carbon from the atmosphere. Furthermore, the higher carbon levels in surface waters make them more acidic – bad news for many forms of ocean life, such as coral and squid.
“This result illustrates how complex the chain of cause and effect can be in the Earth system. No one would ever have predicted from first principles that increasing CFCs would have the effect of decreasing uptake of ocean carbon dioxide,” says Andrew Watson, from the University of East Anglia, UK.
The good news is that we did something serious about CFC emissions years ago, and their level in the atmosphere is indeed coming down, albeit slowly. (See the graph on this page on the US NOAA’s web site for CFC trends since 1978.) In the mean time, we’re likely to see significantly more CO2 staying in the air than would happen otherwise.
What’s “significantly”? Using the figures from the article (2.5 billion tons of carbon, not CO2) over 17 years, that’s about 538 million additional tons/year of CO2, roughly 10% of the US’s current annual CO2 emissions. In this time when every greenie’s favorite parlor game is trying to figure out how we get to an 80% CO2 emissions reduction by 2050, imagine that we suddenly discover that the US’s emissions had leaped by 10% in a single year, and we would be stuck with that yearly increment of CO2 for decades.
The secondary lesson here is another of my favorite themes (read: obsessions): the importance of timing. The world took serious steps to reduce CFC emissions because of what a greatly expanded ozone hole would mean to human beings. At the time we had no idea that in 2009 the climate chaos situation would be as bad as it is, and we certainly didn’t know about this ozone/CO2 uptake connection. In other words, we got lucky, and while the timing of our actions could have been better, it certainly could have been much worse.
