Taking ocean acidification seriously

Oh. There's another link to this blog today (and praise) from Andrew Bolt, and now I'm going to deal with an issue that I expect may earn his scorn. Don't leave me, new readers! I try to be very reasonable about this, you know!

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.

Past ocean acidification considered

Yet another study looking at what happened in a previous big event of volcano driven ocean acidification 120,000,000 years ago. Yes, shell making plankton survived, morphing into smaller sizes, but at the same time the rate of acidification, and the way it changed at depth, is very different to what's happening now:

It took at least 25,000 years for the new acidity levels reached in the surface waters to transfer to deeper waters, according to the research—and the ocean took 75,000 years to reach its peak acidity for that episode, as well as at least 160,000 years to recover. The length of this episode derives "most probably because several CO2 pulses [volcanic eruptions] contributed to ocean acidification," Erba says. Further, she plans to examine other high CO2 events in the geologic record to see "if the same causes—excess CO2, global warming, ocean acidification—trigger similar effects on marine calcifiers at different times."

But the 25,000-year time lag between acidification of the surface waters and deeper waters is mysterious, points out geoscientist Timothy Bralower of The Pennsylvania State University, who was not involved in this study. "In the modern ocean, a similar input of carbon would involve a lag on the order of centuries," he notes. "So something is very different." And the nannoconids begin to disappear even before the fossil record indicates lighter volcanic carbon isotopes—in other words, presumably before the actual acidification.

Here's the crux:

"The current rate of ocean acidification is about a hundred times faster than the most rapid events" in the geologic past, notes marine geologist William Howard of the Antarctic Climate and Ecosystems Cooperative Research Center in Hobart, Tasmania. Plus, the direct impacts of global warming may complicate the picture—just as modern coral suffer from increased bleaching thanks to warmer ocean temperatures as well as the reduced carbonate exoskeleton–building capacity brought on by ocean acidification. Bralower adds: "The big question is whether modern species will be able to adapt to what I expect will be much more rapid pH reduction in coming centuries."

Serious pteropod effects already found (and how Conservative American pundits don't have a clue)

It was only recently that I referred to pteropods as the "canary in the coal mine" for ocean acidification.

Well, they have started to suffer already in one part of the world's ocean:

A NOAA-led research team has found the first evidence that acidity of continental shelf waters off the West Coast is dissolving the shells of tiny free-swimming marine snails, called pteropods, which provide food for pink salmon, mackerel and herring, according to a new paper published in Proceedings of the Royal Society B 

Even though these waters are naturally more acidic from local upwelling, it does not augur well for the future: 

"We did not expect to see pteropods being affected to this extent in our coastal region for several decades," said William Peterson, Ph.D., an oceanographer at NOAA's Northwest Fisheries Science Center and one of the paper's co-authors. "This study will help us as we compare these results with future observations to analyze how the chemical and physical processes of ocean acidification are affecting marine organisms."

Richard Feely, senior scientist from NOAA's Pacific Marine Environmental Lab and co-author of the research article, said that more research is needed to study how corrosive waters may be affecting other species in the ecosystem. "We do know that organisms like oyster larvae and pteropods are affected by water enriched with CO2. The impacts on other species, such as other shellfish and larval or juvenile fish that have economic significance, are not yet fully understood."

 While we're speaking ocean acidification, I was surprised to read recently that conservative commentator Jonah Goldberg had said Republicans should take some environmental issues more seriously, such as ocean acidification.   Many people pointed out that you address both climate change and acidification the same way - by tough action to cut back on fossil fuels - but that is something  about which he is not keen.

Goldberg has had to clarify that he was talking more about geoengineering - such as grinding up mountains of limestone and throwing into the ocean.

Of course, Goldberg has probably not read this recent paper which did not dismiss entirely the possibility of geoengineering, but noted:

The use of ocean-based enhanced weathering [128] could more directly counter ocean acidification, increasing atmospheric CO₂ drawdown through the addition to the ocean of either bicarbonate [129], carbonate minerals [130], calcium hydroxide [131] or combining the addition of liquid CO₂ to the ocean with pulverized limestone [154]. All these approaches, however, involve the transport and processing of considerable bulk of materials, with associated energy costs, in order to achieve globally significant climate benefits. The land-based production of Ca(OH)₂ would also require additional CO₂ sequestration effort (to avoid additional CO₂ release), while the various processes proposed for ‘liming the ocean’ could themselves cause large-scale ecosystem damage, by locally raising pH beyond organisms’ tolerance limits and/or decreasing light penetration, through precipitation effects. 

They also consider ocean fertilization and note its likely problems and limited prospect of large scale CO2 sequestration.

Their conclusion:

The potential for some CDR techniques would seem to warrant further consideration. Nevertheless, strong and rapid mitigation measures, to stabilize atmospheric CO₂ at near-current levels, would provide the policy action most likely to limit ocean acidification and its associated impacts.

The lesson:  even when Republican pundits start trying to sound more open to environmentally friendly policies, they actually have no idea.

Want to take the gamble?

Ocean Acidification: Another Undesired Side Effect Of Fossil Fuel-burning

In this general article about ocean acidification, it is noted:

The expected biological impact of ocean acidification remains still uncertain. Most calcifying organisms such as corals, mussels, algae and plankton investigated so far, respond negatively to the more acidic ocean waters. Because of the increased acidity, less carbonate ions are available, which means the calcification rates of the organisms are decreasing and thus their shells and skeletons thinning. However, a recent study suggested that a specific form of single-celled algae called coccolithophores actually gets stimulated by elevated pCO₂ levels in the oceans, creating even bigger uncertainties when it comes to the biological response.

"There are thousands of calcifying organisms on earth and we have investigated only six to ten of them, we need to have a much better understanding of the physiological mechanisms" demanded Jean-Pierre Gattuso, a speaker from Laboratoire d'Océanographie Villefranche invited by EuroCLIMATE. In addition, higher marine life forms are likely to be affected by the rapidly acidifying oceans and entire food webs might be changing.

This is consistent with what I have said before. You already have big changes underway in ocean chemistry, due to the lag time in the ocean absorbing CO2. With thousands of creatures possibly directly affected, and thousand more in the food chain, it a huge gamble to do no planning for reduced CO2 emissions while waiting another 20 years or so for scientists to get on top of the biology of ocean acidification.

Maybe what is needed is some specific research on something people directly like, such as the effect on prawns or oysters. If research can show that ocean acidification will lead to the decline of the beloved Sydney rock oyster, maybe that would get people's attention.

Actually, now that I Google that topic I see that someone says that prawns and crabs won't be affected because of the way they make their shells. But I am sure I have read somewhere else that krill may be affected. (Maybe that is indirectly because of the effect on some types of plankton.) Anyway, here's the quote from The Telegraph:

Mussels, clams, scallops and oysters are expected to be the worst-hit as the oceans grow more acidic. However prawns, crabs and lobsters will escape unharmed as they produce their shells in a different way.

If the effect on oysters is so clear, I reckon a few good Youtube videos showing the effect might be enough to get ocean acidification more attention. I think at the moment people read about it and shrug their shoulders: there is no direct image of the problem for them to worry about. (Whereas if you concentrate on earth warming, you can do a Gore and use pictures of hurricanes and such like, and whether or not they are truly related to global warming, they have an emotional impact to some people.)

By the way, there are a few new posts up at the Ocean Acidification blog listed in my blogroll.

Let's not forget... ocean acidification

It's been a couple of weeks since I mentioned ocean acidification. You'd think that someone, even George Monbiot, might mention it in the context of "Climategate" (which I still reckon will amount to nothing in the long run) as the other big reason why rapid CO2 increase is Not a Good Idea.

So, what's new from the Ocean Acidification blog?:

a. a couple of types of plankton (two species of coccolithophore) show reduced growth under increased dissolved CO2, even when the increase is more gradual than in some of other experiments;

b. another study on 4 different strains of coccolithophore indicates that they respond differently to increased CO2, presumably on a genetic basis. This is possibly a good thing, if you assume the ones that take increased CO2 in their stride replace those that suffer decreased calcification. But it's going to be very difficult to experimentally tell if that is what will happen in the oceans, I would have thought.

c. a report from an unlikely source (iStockAnalyst!) says that the waters off Japan are showing lower pH:

A group of scientists, led by Takashi Midorikawa of the Meteorological Research Institute in Tsukuba, Ibaraki Prefecture, has checked the pH readings of surface seawater off the Kii Peninsula at 30 degrees north latitude that have been made since 1986. They have found that the pH has dropped by 0.04 during this period, a considerable change. Such ocean acidification has been observed elsewhere as well, such as off Hawaii.

It seems that this is the 3rd report of long term (20 plus years) measurements which are indeed showing that ocean acidification is happening as predicted:

a. the Hawaiian study from earlier this year;
b. the Icelandic ocean study, which has just been updated, and
c. now Japan.

While there seems to be a considerable divergence in the actual rate of acidification, water temperatures and other factors presumably have a role.

Still, it seems that the skeptic response that ocean acidification can't happen (or isn't happening,) which seemed to be the position of Ian Plimer and Bob Carter, for example, just isn't sustainable.

4. Here's an interesting report on current work underway with coring coral in the Caribbean to see if growth rates can be correlated to decreasing pH. It will very interesting if they replicate the findings of a study on Australian coral.

5. Cuttlefish (and other cephalopod?) eggs are affected by decreased pH, but it seems unclear whether in a good way or a bad way. (They absorb less cadmium, but more silver.) All kind of complicated, isn't it?

Future may be worse than thought for coral reefs

Well, what a depressing abstract in Nature Climate Change about the way scientists have been thinking about how acidification may affect coral reefs:

Changes in CaCO3 dissolution due to ocean acidification are potentially more important than changes in calcification to the future accretion and survival of coral reef ecosystems. As most CaCO3 in coral reefs is stored in old permeable sediments, increasing sediment dissolution due to ocean acidification will result in reef loss even if calcification remains unchanged. Previous studies indicate that CaCO3 dissolution could be more sensitive to ocean acidification than calcification by reef organisms. Observed changes in net ecosystem calcification owing to ocean acidification could therefore be due mainly to increased dissolution rather than decreased calcification. In addition, biologically mediated calcification could potentially adapt, at least partially, to future ocean acidification, while dissolution, which is mostly a geochemical response to changes in seawater chemistry, will not adapt. Here, we review the current knowledge of shallow-water CaCO3 dissolution and demonstrate that dissolution in the context of ocean acidification has been largely overlooked compared with calcification.

Back to that ocean problem

Animals are already dissolving in Southern Ocean - environment - 25 November 2012 - New Scientist

It's been ages since I have posted anything about ocean acidification.   I still read about it, but a lot of the studies that have come out in the last year or so have been kind of dull and very technical.   I think there is a realisation that ocean biology, chemistry and ecology are more complicated than previously thought, making forecasts of the effects of ocean acidification a field with a lot of uncertainty.  

I have also been waiting for something more specific about some species that everyone thought would be first affected, and pteropods are high on that list.  So at last there is a study out about them, noting field research from a 2008 field trip.  (They take their time, don't they?).

From the link above:

In a small patch of the Southern Ocean, the shells of sea snails are dissolving. The finding is the first evidence that marine life is already suffering as a result of man-made ocean acidification.

"This is actually happening now," says Geraint Tarling of the British Antarctic Survey in Cambridge, UK. He and colleagues captured free-swimming sea snails called pteropods from the Southern Ocean in early 2008 and found under an electron microscope that the outer layers of their hard shells bore signs of unusual corrosion.

As well as warming the planet, the carbon dioxide we emit is changing the chemistry of the ocean. CO₂ dissolves in water to form carbonic acid, making the water less alkaline. The pH is currently dropping at about 0.1 per century, faster than any time in the last 300 million years....

It gets worse:

Aragonite is still relatively plentiful in most of the ocean, but Tarling suspected that some regions might already be affected by shortages.

He visited the Southern Ocean near South Georgia where deep water wells up to the surface. This water is naturally low in aragonite, meaning the surface waters it supplies are naturally somewhat low in the mineral – although not so much so that it would normally be a problem. Add in the effect of ocean acidification, however, and Tarling found that the mineral was dangerously sparse at the surface.

"It's of concern that they can see it today," says Toby Tyrrell of the National Oceanography Centre in Southampton, UK.

Aragonite-depleted regions are still rare, but they will become widespread by 2050, says Tarling. The polar oceans will change fastest, with the tropics following a few decades after. "These pockets will start to get larger and larger until they meet," he says.

Tyrrell says the Arctic will become undersaturated with respect to aragonite before the Antarctic. Patches of undersaturation have already been seen, for instance off the north coast of Canada in 2008.

The only way to stop ocean acidification is to reduce our CO₂ emissions, Tyrrell says. It has been suggested that we could add megatonnes of lime to the ocean to balance the extra acidity. However, Tyrrell says this is "probably not practical" because the amounts involved – and thus the costs – are enormous.

 

Ocean acidification, melting ice, etc

I see John Quiggin has linked to me as one of only two conservative bloggers who argues strongly for fast action against greenhouse gases. (Harry Clarke is the other.)

Well, I guess that means I had better start posting again on the topic. In fact I have been fighting the battle at another blog lately, with some success I think. (Well, one hopes there is at least one open minded reader of skeptical blogs who I might have influenced.) The blog in question: Jennifer Marohasy. The main target there: Dr Steven Short, who argues against ocean acidification being a cause for concern, but on grounds I have repeatedly challenged in light of reported experiments. He's far from convinced me of the error of my ways, and his labelling of me as a postmodern, Nazi loving imbecile makes me suspect he's not exactly a shining light of reasoned debate.

On the ocean acidification front, there have been a couple of reports of interest recently. One is about a study of some East Pacific coral reefs which are already in low carbonate saturated waters, and how these may be a model for future reefs as saturations levels fall in future. As the "alarmists" would have guessed, these reefs appear to not be well cemented together, and if repeated elsewhere we will presumably have reefs which are more rapidly eroded, and (in likelihood) only able to build fresh coral at a slower rate than before.

As to other effects of acidification, a study on the fertilisation success rates for sea urchins indicates that they are going to find it significantly harder to reproduce in future due to lower ocean pH. The worry is, of course, that no one really knows what other species of sea creatures are going to have reproduction rates affected. There's a hell of a lot of species to test. The implications of a possible widespread effect on reproductive rates has scientists rightly worried:

..Havenhand said. ‘I really hope I’m wrong about the broader implications of our work. However, the available evidence points to the conclusion that at present acidification is the biggest threat to the long-term viability of our ocean ecosystems and especially to key invertebrate species that maintain many of the marine ecosystems on which we rely for food, protection, and recreation.’

I didn't see much of the Four Corners story last night on melting Arctic ice, but I could imagine Andrew Bolt's blood pressure rising as he watched it. I did have a look at one of the extended interviews on the Four Corner's website (the one with Ted Scambos), and he looked very calm, cool and reasonable while expressing the reasons for his great concern. (But, I can hear a skeptic cry, he thought the 2008 melt would be worse than it is. It seems to me that the 2008 ice cover is no where near a recovery of such an extent to dismiss the overal trend to melting.)

I find it hard to imagine how climate skeptics can watch such interviews and maintain their conspiratorial view against the whole of greenhouse warming science.

And anyway, as I say, if ocean acidification alone is a big enough worry (and I reckon it is) then you don't have to worry about temperatures and ice melts at all as being justification for action.

Link to previous articles: any new reader via John Quiggin's is welcome to look back over my previous posts on ocean acidification here.

Ocean Acidification and the PETM

An Ominous Warning on the Effects of Ocean Acidification by Carl Zimmer: Yale Environment 360

Quite a good article here explaining a recent paper that compared the rate of acidification 55 million years ago during one gigantic natural disaster to the current circumstances.

Here's a key paragraph:

Ridgwell and Schmidt found that ocean acidification is happening about ten times faster today than it did 55 million years ago. And while the saturation horizon rose to 1,500 meters 55 million years ago, it will lurch up to 550 meters on average by 2150, according to the model.

The PETM was powerful enough to trigger widespread extinctions in the deep oceans. Today’s faster, bigger changes to the ocean may well bring a new wave of extinctions. Paleontologists haven’t found signs of major extinctions of corals or other carbonate-based species in surface waters around PETM. But since today’s ocean acidification is so much stronger, it may affect life in shallow water as well. “We can’t say things for sure about impacts on ecosystems, but there is a lot of cause for concern,” says Ridgwell.

Ocean acidification skeptics from Plimer down are always arguing that the oceans didn't die when CO2 was much higher than today. The answer to that point is again explained clearly in the article:

A hundred million years ago, there was over five times more carbon dioxide in the atmosphere and the ocean was .8 pH units lower. Yet there was plenty of calcium carbonate for foraminifera and other species. It was during this period, in fact, that shell-building marine organisms produced the limestone formations that would eventually become the White Cliffs of Dover.

But there’s a crucial difference between the Earth 100 million years ago and today. Back then, carbon dioxide concentrations changed very slowly over millions of years. Those slow changes triggered other slow changes in the Earth’s chemistry. For example, as the planet warmed from more carbon dioxide, the increased rainfall carried more minerals from the mountains into the ocean, where they could alter the chemistry of the sea water. Even at low pH, the ocean contains enough dissolved calcium carbonate for corals and other species to survive.

Today, however, we are flooding the atmosphere with carbon dioxide at a rate rarely seen in the history of our planet. The planet’s weathering feedbacks won’t be able to compensate for the sudden drop in pH for hundreds of thousands of years.

More on acidification

Acidifying oceans add urgency to CO2 cuts

This report notes an article on ocean acidification that is to appear in the July 4 issue of Science (although I can't see mention of it yet on the Science website.)

As I suspected, it's bad news for you oyster and mussel lovers out there who expect to be around in 50 year's time. But the worrying thing is, it is extremely difficult to be certain how it will affect the oceans and the planet overall:

"We know that ocean acidification will damage corals and other organisms, but there's just no experimental data on how most species might be affected," says Caldeira. "Most experiments have been done in the lab with just a few individuals. While the results are alarming, it's nearly impossible to predict how this unprecedented acidification will affect entire ecosystems." Reduced calcification will surely hurt shellfish such as oysters and mussels, with big effects on commercial fisheries. Other organisms may flourish in the new conditions, but this may include undesirable "weedy" species or disease organisms.

Though most of the scientific and public focus has been on the climate impacts of human carbon emissions, ocean acidification is as imminent and potentially severe a crisis, the authors argue.

"We need to consider ocean chemistry effects, and not just the climate effects, of CO2 emissions. That means we need to work much harder to decrease CO2 emissions," says Caldeira. "While a doubling of atmospheric CO2 may seem a realistic target for climate goals, such a level may mean the end of coral reefs and other valuable marine resources."

While on the topic, I note that Jennifer Marohasy recently posted 2 photos from diver Bob Halstead showing an area in New Guinea which has (apparently) volcanic CO2 bubbling up through the sea floor.

As with the recent Nature study of a similar site in Italy, the photo indicates that sea grass really loves those conditions. Halstead also says there is a "healthy reef" metres away. But it's impossible to take that as proof that corals will happily survive acidified oceans unless you have proper measurements of the pH in the area. Indeed, we don't even know for sure that the gas is all CO2.)

I think we can take it as a sign that sea grass will do well enough in future, but just how ecologically healthy is it to have sea grasses booming in areas where they previously have not been? Especially if they replace areas that are have been extensively coral for tens of thousands of years?

I also see that the ocean acidification sceptics in the comments following that post are relying solely on Dr Floor Anthoni as their source. As I have noted before, the good doctor does not claim to have any qualification in science or biology, and appears to be pretty much an enthusiatic amateur when it comes to marine ecology and chemistry. That's not to say that amateurs can't do good science, but if you are promoting theories that are somewhat outside the mainstream, the lack of a qualification even close to the field (the qualification is in computers and electronics in Dr Anthoni's case) is not exactly adding to your credibility.

Dr Anthoni appears to have irritated many scientists in the past with claims relating to fisheries, etc. To his credit, he appears to at least be open about the disputes he has had, and you can read the exchanges on his own website.

Still, it gives me no comfort if he is the primary source of the ocean acidification sceptic's arguments.

Confirmation that ocean acidification is a scary experiment without precedent

Modern ocean acidification is outpacing ancient upheaval, study suggests

 I'm sure we've seen this conclusion about the comparative rate of ocean acidification from previous studies, but still:

Some 56 million years ago, a massive pulse of carbon dioxide into the atmosphere sent global temperatures soaring. In the oceans, carbonate sediments dissolved, some
organisms went extinct and others evolved.

Scientists have long suspected that ocean acidification played a part in the crisis—similar to today, as manmade CO2 combines with seawater to change its chemistry. Now, for the first time, scientists have quantified the extent of surface acidification from those ancient days, and the news is not good: the oceans are on track to acidify at least as much as they did then, only at a much faster rate.

In a study published in the latest issue of Paleoceanography, the scientists estimate that surface ocean acidity increased by about 100 percent in a few thousand years or more, and stayed that way for the next 70,000 years. In this radically changed environment, some creatures died out while others adapted and evolved. The study is the first to use the chemical composition of fossils to reconstruct surface ocean acidity at the Paleocene-Eocene Thermal Maximum (PETM), a period of intense warming on land and throughout the oceans due to high CO2.

"This could be the closest geological analog to modern ocean acidification," said study coauthor Bärbel Hönisch, a paleoceanographer at Columbia University's Lamont-Doherty Earth Observatory. "As massive as it was, it still happened about 10 times more slowly than what we are doing today."

 And the oceans do not fix themselves quickly:

The study confirms that the acidified conditions lasted for 70,000 years or more,
consistent with previous model-based estimates.

"It didn't bounce back right away," said Timothy Bralower, a researcher at Penn State who was not involved in the study. "It took tens of thousands of years to recover."

Ocean acidification worries noted, yet again

This BBC report paints a worrying picture of some recent research on ocean acidification.  First the UK's chief scientist:

“If we carry on emitting CO2 at the same rate, ocean acidification will create substantial risks to complex marine food webs and ecosystems.”

He said the current rate of acidification is believed to be unprecedented within the last 65 million years – and may threaten fisheries in future.

The consequences of acidification are likely to be made worse by the warming of the ocean expected with climate change, a process which is also driven by CO2.

Sir Mark’s comments come as recent British research suggests the effects of acidification may be even more pervasive than previously estimated.

Until now studies have identified species with calcium-based shells as most in danger from changing chemistry.

But researchers in Exeter have found that other creatures will also be affected because as acidity increases it creates conditions for animals to take up more coastal pollutants like copper.

The angler’s favourite bait – the humble lugworm – suffers DNA damage as a result of the extra copper. The pollutant harms their sperm, and their offspring don’t develop properly.

“It’s a bit of a shock, frankly,” said biologist Ceri Lewis from Exeter University, one of the report’s authors. “It means the effects of ocean acidification may be even more serious than we previously thought. We need to look with new eyes at things which we thought were not vulnerable.”

The lugworm study was published in Environmental Science and Technology. Another study from Dr Lewis not yet peer-reviewed suggests that sea urchins are also harmed by uptake of copper. This adds to the damage they will suffer from increasing acidity as it takes them more and more energy to calcify their shells and spines.

This is significant because sea urchins, which can live up to 100 years, are a keystone species - grazing algae off rocks that would otherwise be covered in green slime.

The article does go on to make this comment, too, but I think it is actually too optimistic a take on some recent, but still very limited, studies:

At the bottom end of the marine animal chain, tiny creatures like plankton and coccolithophores reproduce so fast that their future offspring are likely to evolve to cope with lower pH.

Revisiting ocean acidification

I’m pretty busy this week, but if I can get readers to look at one article, it would be the very balanced one that appeared in The Economist on ocean acidification.

The article’s subtitle is “ocean acidification threatens the world’s oceans, but quantifying the risks is hard”, which is probably a fair statement given the current state of play in the research.  

It has always been suggested that there will likely to be winners and losers in the ocean from acidification, and this year some researchers have proposed that a meta-analysis of studies to date indicate that sea life may be more resilient than originally thought.  This has been immediately attacked by other researchers pointing out the complexity of the problem:  you have to look at how lower pH affects organisms at all stages of life, as well as warming ocean temperatures, and nutrient levels too.

There are still studies just coming out which have tried to work out more details as to different species’ responses.   Here are a few:

*  it’s still not looking great for the pteropods, one of the major fish foods of the cold oceans, although this study got some results a bit different from previous ones, and much uncertainty seems to remain.  (In fact, my general impression from reading  about this topic for a number of years now is that there is still a surprising lack of detailed knowledge about the detailed bio-chemistry of  sea creatures that build shells, in particular.) 

*  for the blue mussel, the effects on the larval stage are not good.

* on the other hand, for one species of clam, lower pH seemed to do no harm at all.

The problem with some of these studies must surely be how hard it is to accurately replicate the ocean environment in the lab for certain creatures, particularly if they don’t just float at one depth all day, as is the case (I seem to recall) with pteropods.

There has also been renewed comment about how widely the pH of ocean areas (particularly near the coast, I think) changes naturally in a short space of time.  The suggestion is that if creatures can survive that already, they are possibly resilient to forecast lowering of pH.  Yet, surely a significant drop of the  average pH a creature experiences during the day could be very important, even if the same creature spends part of its day/week at such a lower pH already.

Anyhow, as I said, The Economist article does a good job at explaining the current uncertainties, and suggests that it may well be coral reef studies that come up with the definitive proof that acidification will have major effects.  Here are the concluding paragraphs:

If reshaping food webs marginalises the pteropods, the salmon will have to adapt or die. But though the mesocosms may shed light on the fate of the pteropods, the outlook for the salmon will remain conjectural. Though EPOCA is ambitious, and expensive, the mesocosms are too small to contain fish, and the experiments far too short to show what sort of adaptation might be possible over many years, and what its costs might be.

This is one of the reasons why the fate of coral reefs may be more easily assessed than open-water ecosystems. The thing that provides structure in open-water ecosystems is the food-web, which is hard to observe and malleable. In reefs, the structure is big lumps of calcium carbonate on which things grow and around which they graze and hunt. Studies of Australia’s Great Barrier Reef show that levels of calcification are down, though it is not yet possible to say changes in chemistry are a reason for this. Current research comparing chemical data taken in the 1960s and 1970s with the situation today may clarify things.

But singling out the role of acidification will be hard. Ocean ecosystems are beset by changes in nutrient levels due to run off near the coasts and by overfishing, which plays havoc with food webs nearly everywhere. And the effects of global warming need to be included, too. Surface waters are expected to form more stable layers as the oceans warm, which will affect the availability of nutrients and, it is increasingly feared, of oxygen. Some, including Dr Riebesell, suspect that these physical and chemical effects of warming may prove a greater driver of productivity change in the ocean than altered pH. Wherever you look, there is always another other problem.

No reason for complacency, I say.

Future krill kill?

Risk maps for Antarctic krill under projected Southern Ocean acidification : Nature Climate Change : Nature Publishing Group

Hey, this blog must one of the few in the world that is always interested in krill stories.   If you search at the sidebar, you'll find at least six posts in the past.

And today, another article in Nature Climate Change (above) with concerns that ocean acidification will eventually kill them off in Antarctica, with dire consequences for the whole food chain.  I'll cut and paste the whole summary, because it has interesting bits about the entire krill life cycle (who knew their eggs hatched so deep?):

Marine ecosystems of the Southern Ocean are particularly vulnerable to ocean acidification¹. Antarctic krill (Euphausia superba; hereafter krill) is the key pelagic species of the region and its largest fishery resource². There is therefore concern about the combined effects of climate change, ocean acidification and an expanding fishery on krill and ultimately, their dependent predators—whales, seals and penguins^{3, 4}. However, little is known about the sensitivity of krill to ocean acidification. Juvenile and adult krill are already exposed to variable seawater carbonate chemistry because they occupy a range of habitats and migrate both vertically and horizontally on a daily and seasonal basis⁵. Moreover, krill eggs sink from the surface to hatch at 700–1,000 m (ref. 6), where the carbon dioxide partial pressure (p_CO2) in sea water is already greater than it is in the atmosphere⁷. Krill eggs sink passively and so cannot avoid these conditions. Here we describe the sensitivity of krill egg hatch rates to increased CO₂, and present a circumpolar risk map of krill hatching success under projected p_CO2 levels. We find that important krill habitats of the Weddell Sea and the Haakon VII Sea to the east are likely to become high-risk areas for krill recruitment within a century. Furthermore, unless CO₂ emissions are mitigated, the Southern Ocean krill population could collapse by 2300 with dire consequences for the entire ecosystem.

Ocean acidification is not going away

Ocean acidification only pops its head up occasionally in the media now as a dire threat from increasing CO2 in the atmosphere:  probably because it is such an incremental change that it doesn't have the ring of immediate alarm about climate change as do heat waves, floods or fires. 

But it's not going away, even if it is pretty difficult to study.    (Replicating the effect in laboratory settings turned out to be a lot trickier than initially realised.)

There's a new study out on how it affects ocean areas with naturally venting CO2.  I'm sure we've seen similar studies in other places, but it confirms that the future of the coastal areas under high CO2 is more likely green and slimy with less biodiversity:

To assess the likely ecological effects of ocean acidification we compared intertidal and subtidal marine communities at increasing levels of pCO₂ at recently discovered volcanic seeps off the Pacific coast of Japan (34° N). This study region is of particular interest for ocean acidification research as it has naturally low levels of surface seawater pCO₂ (280–320 µatm) and is located at a transition zone between temperate and sub-tropical communities. We provide the first assessment of ocean acidification effects at a biogeographic boundary. Marine communities exposed to mean levels of pCO₂ predicted by 2050 experienced periods of low aragonite saturation and high dissolved inorganic carbon. These two factors combined to cause marked community shifts and a major decline in biodiversity, including the loss of key habitat-forming species, with even more extreme community changes expected by 2100. Our results provide empirical evidence that near-future levels of pCO₂ shift sub-tropical ecosystems from carbonate to fleshy algal dominated systems, accompanied by biodiversity loss and major simplification of the ecosystem.

 A report on the study explains:

They found that while a few plant species benefitted from the changing conditions, they tended to be smaller weeds and algae that blanket the seabed, choking corals and lowering overall marine diversity.

These species, and some smaller marine animals, are thriving because they are more tolerant to the stress posed by rising levels of CO₂.

Jason Hall-Spencer, Professor of Marine Biology at the University of Plymouth, said: "Our research site is like a time machine. In areas with pre-Industrial levels of CO₂ the coast has an impressive amount of calcified organisms such as corals and oysters. But in areas with present-day average levels of surface seawater CO₂ we found far fewer corals and other calcified life, and so there was less biodiversity. It shows the extensive damage caused by humans due to CO₂ emissions over the past 300 years and unless we can get a grip on reducing CO₂ emissions we will undoubtedly see major degradation of coastal systems worldwide."

Ocean acidification update, part whatever..

Some recent studies report:

* subtropical corals showing a net loss of calcium carbonate under decreased ocean pH:

These experimental results provide support for the conclusion that some net calcifying communities could become subject to net dissolution in response to anthropogenic ocean acidification within this century.

* the results of experiments on a couple of planktonic foraminifera (which are a small critter that produces calcium carbonate shells) do not like more CO2:

At the [CO32−] expected for the end of the century, the calcification rates of these two species are projected to be 6 to 13% lower than at present conditions, while the final shell weights are reduced by 20 to 27% for O. universa and by 4 to 6% for G. sacculifer. These results indicate that ocean acidification would impact calcite production by foraminifera and may decrease the calcite flux contribution from these organisms.

* bivalves in Antarctic waters (the first predicted to suffer increased ocean acidification) don't take it well either:

After 5 weeks the shells and thallus of the coralline alga had suffered significant dissolution when compared to controls. Moroever, one of the shells of the bivalve L. elliptica in acidified seawater became so fragile it fragmented into multiple pieces. Our findings indicate that antarctic calcified seafloor macroorganisms, and the communities they comprise, are likely to be the first to experience the cascading impacts of ocean acidification.

* Pteropods, and important fish food, show significantly reduced calcification at pH levels predicted for 2100:

This result supports the concern for the future of pteropods in a high-CO2 world, as well as of those species dependent upon them as a food resource. A decline of their populations would likely cause dramatic changes to the structure, function and services of polar ecosystems.

Remember, boys and girls, reducing CO2 is not just about warming.

Ocean acidification updated – not much to celebrate

A news blog in Nature has some bad news:

Thanks to rising carbon dioxide (CO₂) levels, some Arctic waters are already experiencing pH dips that could be harmful to sea life. What’s more, this acidification seems to be happening more rapidly than models have predicted.

This sobering conclusion was reached by researchers who met on Wednesday to discuss ocean acidification at the Geological Society of America meeting in Denver. “Models are probably underestimating at least by a few years the impact of ocean acidification in the Arctic,” says Jeremy Mathis, a chemical oceanographer at the University of Alaska in Fairbanks. “We don’t know what the organisms’ responses are yet, but the conditions are already there to potentially be disruptive to the ecosystems.”

Marine organisms from plankton to crabs are dependent on carbonate ions in the ocean to build their skeletons and shells. But as CO₂ dissolves in the water it lowers the pH, which shrinks the pool of such ions available for animals to use.

One important source of carbonate ions is aragonite, a particularly soluble form of calcium carbonate. Seawater is usually saturated with aragonite. However a recent study in Biogeosciences estimated that by 2016, according to the IPCC’s mid-range emissions projections, aragonite will fall below this level in some Arctic waters for at least one month a year. By the end of the century, it predicts that the entire Arctic Ocean could be under-saturated with respect to aragonite.

“But we don’t have to wait until 2016,” says Mathis. “We’re already seeing places in the Arctic where these under-saturations are happening now.” High latitude waters in the Arctic and Antarctic are particularly sensitive to pH changes, as cold waters absorb more gas than warm waters.

Researchers at the symposium were particularly concerned about pteropods – tiny sea snails that are highly sensitive to acidification. Pteropods make up about half the diet of juvenile pink salmon living in Gulf of Alaska. And they could be affected at pH levels very close to those that the region is already experiencing. “It’s not going to take a great deal of CO₂ intrusion in high latitude seas to get to a point where the water could become corrosive to some marine calcifying organisms,” says Mathis.

As for the pteropods, decreasing pH is not good for them, but nor is increasing termperatures. A recent study reports:

We conclude that pre-winter juveniles will be negatively affected by both rising temperature and pCO₂ which may result in a possible abundance decline of the overwintering population, the basis for next year's reproduction.

Also, another recent study estimating pH changes in the Meditteranean reports:

For the first time, the level of acidification is estimated for the Mediterranean Sea. Our results indicate that for the year 2001 all waters (even the deepest) have been acidified by values ranging from -0.14 to -0.05 pH unit since the beginning of the industrial era, which is clearly higher than elsewhere in the open ocean.

And down around Australia, for those who love their Sydney rock oysters, a study suggests that they may be replaced by the bigger Pacific oyster due to increasing CO2 in the oceans. Pay attention, rock oyster lovers.

The only “upside” are some studies arguing that some coastal phytoplankton that are already used to large swings in water pH may not suffer as CO2 increases. It doesn’t tell us much about the wider ocean, though.

These studies took their time

Acidic oceans threaten fish : Nature News & Comment

I've become slack about posting items concerning ocean acidification. This is partly because a lot of the studies being reported at the Ocean Acidification blog have become very technical in nature - examining in minute detail the biochemistry of marine organisms and trying to tell exactly how ocean chemistry affects it - and also because there doesn't seem to have been much reported lately on the rate of acidification.

But still, I should go back and catch some of the stories that I have missed.

Anyway, today there is a Nature report (see above) about a couple of studies indicating that young larvae of a couple of fish do not do well under acidification.

Skeptics will no doubt have a couple of objections: firstly, some coastal waters where fish breed already have a really high range of natural pH. I doubt that this is a valid objection, as an increase in acidification from the atmosphere just means that the range is going to shift its mean and peaks to the high end, so it still may be a problem. The second issue will be whether natural selection will mean fish will be able to evolve quickly to adapt to the new acidification regime.

Quick adaptation to warmer sea warmers was indicated in a recent Australian study, but whether this will apply to acidification is anyone's guess.

On the downside of the warmer water story, another study recently indicated that fish parasites can do better in warmer water, which just shows how complicated it is trying to work out the net effect of warming oceans and increasing acidification.

Still, it surprises me somewhat that it took this long for a studies on fish larvae mortality under increased acidification took this long to be done.

The future of coccoliths

Ocean acidification: Carbon dioxide makes life difficult for algae

Here's some bad ocean acidification news for us all, about coccoliths (the calcium carbonate shells of some algae.)

"We know that the world's oceans are acidifying due to our emissions of CO₂ and that is why it is interesting for us to find out how the coccoliths are reacting to it. We have studied algae from both fossils and living coccoliths, and it appears that both are protected from dissolution by a very thin layer of organic material that the algae formed, even though the seawater is extremely unsaturated relative to calcite. The protection of the organic material is lost when the pH is lowered slightly. In fact, it turns out that the shell falls completely apart when we do experiments in water with a pH value that many researchers believe will be the found in the world oceans in the year 2100 due to the CO₂ levels," explains Tue Hassenkam, who is part of the NanoGeoScience research group at the Department of Chemistry, University of Copenhagen.

Professor of Biological Oceanography Katherine Richardson has followed research in the acidification of the oceans and climate change in general and she hopes that the results can help to bring the issue into public focus.

"These findings underscore that the acidification of the oceans is a serious problem. The acidification has enormous consequences not only for coccoliths, but also for many other marine organisms as well as the global carbon cycle.".....

And from the abstract of the PNAS paper itself:

However, ancient and modern coccoliths, that resist dissolution in Ca-free artificial seawater at pH > 8, all dissolve when pH is 7.8 or lower. Ocean pH is predicted to fall below 7.8 by the year 2100, in response to rising CO2 levels. Our results imply that at these conditions the advantages offered by the biogenic nature of calcite will disappear putting coccoliths on algae and in the calcareous bottom sediments at risk.

This is the worst sounding bit of ocean acidification research that has come out for quite some time.

Contradictory evidence

Study Sees an Advantage for Algae Species in Changing Oceans - New York Times

Bah! Just after I spend time catching up on ocean acidification, and trying to encourage readers to worry about the effect on carbonate-incorporating algae, a new study indicates that they have actually done better under increased CO2 levels, contrary to previous studies and expectations. (Who would have guessed that it makes a difference if you bubble gas into the water, rather than simply add acid to it?)

Neither the article above, or the other one it links to, talk about whether this means this is an automatic way the earth is increasing the oceans as a CO2 sink. But my guess is that it can't be hurting in that regard.

However, the article also says that this research doesn't mean the coral reefs are safe from acidification.

And: I also wonder whether someone will come up with a concern about too much algae being produced in some regions with too much acidification. As I mentioned in my earlier post, I didn't think you really wanted a lot of certain types of algae in shallow waters.

More information required.

And no gloating please, Andrew Bolt.

UPDATE: It gets worse (for my previous post.) According to the Ocean Acidification blog, there's an article in Science that is claiming we simply don't know enough to be able to dismiss coral reef's ability to adapt to increased acidification. I think the suggestion is that other types of coral will simply replace the ones that are more sensitive to it.

But then: the worriers have made a response already. And they make the point that, when corals have disappeared in the past due to high ocean acidification, they have taken millions of years to recover.

It's a big gamble, isn't it? My gut reaction is still that increasing the acidity of the entire ocean by a factor of 2 or 3 over a relatively short period of time (a century or so?) is a dangerous experiment to be playing. We can't even stop the first part of it, due to the lag time in CO2 absorption, but we can try and stop the worst of it.