It's been quite a while since I explained why I decided it's a good idea to reduce CO2 production, and to do it with urgency. My position is that it doesn't matter whether or not the Earth is looking cooler for a year or two at the moment: the effect of ocean acidification is something that started being viewed with serious alarm by marine scientists over the last 5 years especially, and that concern is not going away.
For some easy to read primers on the problem, try these three Australian sites here, here and here. (Australia has special reason to be concerned, as will become apparent soon.) The lengthy Royal Society report of 2005 on this, which is actually pretty easy to read, is here.
I'll list a few key points so you don't even have to follow the links:
a. increased atmospheric CO2 levels have already increased the acidity level of the ocean by 30% over the last couple of hundred years;
b. the steep climb expected in further CO2 emissions on a "business as usual" scenario could lead to about a 300% increase in acidity, although even then it will be slightly alkaline. (If you want to, you can insist that the change be called a reduction in ocean alkalinity instead of an increase in acidity; it makes no difference to the life that lives there.)
c. even if all CO2 production stopped today, the ocean will continue getting more acid by at least the same amount as it already has, and it will take thousands of years for ocean chemistry to get it back to pre-industrial levels. (The chemistry of the earth means that even when the ocean has been much more acidic, it eventually comes back to something close to what we've currently had for a long time - see the next point.)
d. ocean pH is believed not to have been as low as its current level for a very long time (one article mentions 430,000 years; another mentions 40 million years, but I am not sure which pH level it is referring to.) One article indicates that if "business as usual" continued beyond 2100, the oceans will eventually get to a pH that hasn't been seen for 300 million years! In any case, it's the rate of current change that is a big part of the problem:
During the Ordovician, atmospheric carbon levels were much higher, but had risen gradually, allowing the oceans to remain saturated with calcium carbonate, and life had flourished.But, 250 million years ago, the formation of the Siberian Traps through a massive volcanic eruption caused a sudden and massive shift in oceanic pH, and nearly 90 percent of oceanic species went extinct. He noted that the extinctions followed lines that were predictable; species we'd expect to be sensitive to carbonate concentrations died, while those that have finer control over their physiology largely made it through the extinctions.
e. Australians have good reason to worry: cold water takes in CO2 faster, and the large Southern Ocean waters should therefore become most acidic first, and the acidity levels are expected to spread north. Warm water coral reefs might already be being affected by sensitivity to even the current levels of increased acidity, although there are still uncertainties about this.
On the Science Show this week, some scientists express their deep concern.
Look, no one says that the oceans will go completely and utterly barren everywhere, but the concern is that the change from what they are like now could be very dramatic indeed, over a very short space of time. Most significantly here in Australia, is the possible absolute collapse of coral reefs as we know them. In that Science Show transcript, one American scientist notes:
Unfortunately the picture for acidification is much fuzzier but also much uglier, and that's because corals seem to have little in the way that they can escape from the effects of acidification. It's actually the case that corals can survive, at least in the laboratory, in highly acid waters, but they turn into little sea anemones, they stop building skeletons altogether. As a consequence what you will have is a world of coral reefs but coral reefs without skeletons, which really aren't reefs at all. So that these structures that we can see from space and which so many organisms depend upon in terms of the three-dimensional complexity will simply cease to exist.Even if you view large scale changes to the reefs of the world as only an aesthetic loss, the other major concern noted in the various articles is that acidification affects many types of plankton, upon which much bigger things feed, which in turn are eaten by things on which humans like to feast. And these plankton also have a role in sinking CO2 to the bottom of the ocean, so if their population goes down, more CO2 is left to go into the ocean to make it more acid, etc.
Of course, the scientists are still working on it all, and the ecological effects of such large scale change are not entirely clear. But I think from a common sense point of view, massive changes in ocean ecology sound dangerous. And remember that it will take thousands of years for pH to drop. (Adding stuff to the oceans to make them less acidic would have to be on such a large and expensive scale it doesn't really seem feasible, although there are people coming up with ideas.)
In an earlier post about this, I mentioned that I would like to see any skeptical arguments about ocean acidification. (Andrew Bolt correctly points out that some predictions of the Great Barrier Reef's demise due to ocean warming have, at the very least, been very premature. But Andrew's hope today that a reef's ability to recover from a nuclear blast is a good sign doesn't exactly address the big picture of acidification. Acidification is a much more long term process, that is already well underway.)
Googling for "ocean acidification skeptics" doesn't bring up much. Some have taken recently to (rather conspiratorially) claiming that scientists are starting to "talk up" ocean acidification because they realise that recent cooler temperatures mean people will stop believing in global warming. (Of course, as even the articles listed here indicate, many marine scientists have been talking about it with alarm for the last few years in particular, ever since the Royal Society report of 2005 really gave the issue a lot of attention.)
The only site I have found (admittedly in a quick search) with a detailed attempt to rebut ocean acidification science is here, by one Dr Floor Anthoni of a New Zealand group called "Seafriends". Dr Anthoni appears to have no academic background in biology; his qualifications seem to be only in computer science and electronics.
He claims that some of his own discoveries mean that ocean acidification is not property understood, and it will not be as big disaster as predicated. (He claims the ocean will become "more productive", but also says "...there could be some unexpected and unforeseen surprises. The world has been changing and adapting to major changes since it came out of the last ice age, and the changes caused by fossil fuel will be relatively small.")
Well, I would be inclined to take Dr Anthoni more seriously if he actually had qualifications in a relevant field, and didn't come across as a generic contrarian on most things to do with the greenhouse gas issue.
It seems that, more so than with climate change due to greenhouse, it is extremely hard to find a scientist in the field who doubts the serious ecological consequences of large amounts of CO2 in the oceans.
Here's my concluding thought: at least with global warming, it is possible to argue there will some "upside". Fewer people in colder countries will die during winter, plants may grow faster to supply food, the residents of Greenland are already happier; that kind of thing. And to look at the really big picture, surely the world is better off being quite a few degrees hotter than having much of North American and Europe under hundreds of meters of ice. (That's the scenario of global warming preventing an overdue ice age.)
Ocean acidification on the other hand seems to have no upside at all. (I am discounting the credibility of Floor Anthoni on this.)
The only thing that may seem a vague "positive" is that some research noted in the Ocean Acidification blog seems to indicate that some algae may do better. But (from memory, without having time to Google this right now) algal blooms don't have a good reputation, especially in shallow coastal waters, where their decay sucks the oxygen out of the sea and makes it sterile of larger life. Algal blooms in the deep ocean might have some carbon sink effects, but the reason iron fertilization of the ocean is viewed with much scientific skepticism is due to the uncertainty as to whether the carbon taken in really does make it to the bottom of the sea for any length of time.
Overall, the change of all coral reefs into something with much, much less diverse life, and fewer carbon sinking plankton in the deep ocean, will surely be a bad thing, with food chain and other consequences that indeed sound worrying.
I also haven't even repeated here the point in my original post that past CO2 levels of just under 1,000 ppm (we're well over a third of the way there) were around when some scientists think that anoxic oceans made large amounts of hydrogen sulphide which killed land animals in mass extinctions.
It seems fully deserving of all the attention it can get, and as I said at the start, is of itself a compelling reason to take the need for urgent CO2 reduction very seriously.
Tell me where I am wrong...
UPDATES: I've been fiddling with this post all day, adding stuff mostly.
I actually have found a post by an academic who briefly mentions some reasons for thinking that coral reefs (and some plankton/algae) may be more adaptable to pH change than some fear. But he notes that the lab experiments are (so far) contradictory on the issue. It's not enough to relieve my concerns.
Jennifer Marohasy's blog contains lots of skeptical posts about coral reef danger, although a lot of them are on the issue of warming waters, not acidification.
Professor Ove Hoegh-Gulberg, who Andrew Bolt strongly criticised for exaggerating coral reef danger, has his own blog too. He admits his early predictions were too dire about the speed with which reefs could die, but I think he defends himself pretty well overall. Have a look at this thread in which he debates Peter Ridd.
A clarification: at one point I mention some types of plankton as having a role as carbon sinks, but later I mention the skepticism about whether algae is an efficient carbon sink. I think they are not contradictory statements because plankton and algae come in different varieties, only some of which use carbonate and are likely to be the best at being permanent carbon sinks. If that type doesn't grow so well in acidified oceans, the plankton/algae mix may swing towards the type which is not likely to be good at taking up carbon permanently, even if you do have more of them due to "fertilization" by CO2.
Correct me anyone if you think I have misread that from the articles.
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