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?

Some plankton doing well, for now...

Published Thursday in the journal Science, the study details a tenfold increase in the abundance of single-cell coccolithophores between 1965 and 2010, and a particularly sharp spike since the late 1990s in the population of these pale-shelled floating phytoplankton.

"Something strange is happening here, and it's happening much more quickly than we thought it should," said Anand Gnanadesikan, associate professor in the Morton K. Blaustein Department of Earth and Planetary Sciences at Johns Hopkins and one of the study's five authors.

Gnanadesikan said the Science report certainly is good news for creatures that eat coccolithophores, but it's not clear what those are. "What is worrisome," he said, "is that our result points out how little we know about how complex ecosystems function." The result highlights the possibility of rapid ecosystem change, suggesting that prevalent models of how these systems respond to climate change may be too conservative, he said.

The team's analysis of Continuous Plankton Recorder survey data from the North Atlantic Ocean and North Sea since the mid-1960s suggests rising carbon dioxide in the ocean is causing the coccolithophore population spike, said Sara Rivero-Calle, a Johns Hopkins doctoral student and lead author of the study.

Link to the story here.

This is interesting, given that coccolithophores have been the subject of some intensive study to work out whether they are very sensitive to ocean acidification, or not.  (The results of lab tests have been contradictory and it's been difficult to work out why.)    The concern is (I expect) that at a certain threshold of CO2, this type of plankton suddenly goes into reverse because of the acidification effect. 

Your weekly ocean acidification news

Comment on "Phytoplankton Calcification in a High-CO2 World" -- Riebesell et al. 322 (5907): 1466b -- Science

Readers interested in my ocean acidification posts* will recall that there was a big surprise earlier this year when one study suggested that one species of calcifying phytoplankton actually got substantially heavier with more CO2 in the water.

The suggestion was that this may work as an important new CO2 sink, and was quite contrary to previous studies which showed the coccolithophore shells getting smaller with increased ocean acidity.

There was some muttering at the time by other scientists that this study could have been flawed, and now, see the link for a detailed comment by a group of scientists who think they have the problems with the experiment.

The comment is worth reading as setting out the basic issues with acidification and calcification.

Basically, this group still sounds very pessimistic about the "winners" outweighing the "losers" in ocean acidification.

* and who knows if there are any? - no one ever comments on those posts, which just encourages me to continue grinding my teeth about how most of the world is ignoring this issue.

Bad ocean acidification news

Shell-shocked: Ocean acidification likely hampers tiny shell builders in Southern Ocean

The coccolithophore E. huxleyi is important in the marine carbon cycle and is responsible for nearly half of all calcium carbonate production in the ocean, said lead study author Natalie Freeman, a doctoral student in the CU-Boulder'sDepartment of Atmospheric and Oceanic Sciences (ATOC). The new study indicates there has been a 24 percent decline in the amount of calcium carbonate produced in large areas of the Southern Ocean over the past 17 years.

The researchers used satellite measurements and statistical methods to calculate the calcification rate - the amount of calcium carbonate these organisms produced per day in surface ocean waters. Across the entire Southern Ocean, which surrounds Antarctica, there was about a 4
percent reduction in calcification rate during the summer months from 1998 to 2014. In addition, the researchers found a 9 percent reduction in calcification during that period in large regions of the Pacific and Indian sectors of the Southern Ocean.

Not quite sure how those percentages add up to 24% - I suppose it has to do with the area over which the reductions happen.

Anyhow, sounds bad.