In response to my comments on her appearance on BBC news, Daniela Schmidt has tweeted some thoughts. Recall that I highlighted some comments she had made in a Geology paper about calcifier exctinctions occurring tens of thousands of years after extreme temperatures were reached, contrasting this with her on-air claim that the oceans were doomed by the end of the century:
My children will be alive in 2100. I would like them to be able to swim above a coral reef and enjoy its beauty. I would like them to be able to eat mussels and oysters and crayfish and if we continue to release CO2 at the current rate this is not going to happen.
Prof Schmidt has apparently told Roger Harrabin that I have misunderstood her work. In a tweet she notes that her comments in Geology represented a citation of other scientists:
the document is a news item and not a scientific paper. Nobody ever claimed it was.
this is not my finding. I am spectically discussing data of others as cited in the news item
Fair enough. But if the scientific literature is contradictory, how is it justifiable to say the things she did to Roger Harrabin about corals, mussels and oysters?
She goes on to recommend some reading for me.
please look at Hoenisch et al 2012, Rigdwell, Schmidt NatGeo 2010 before you make claims
Ridgwell is paywalled, but it is a computer simulation anyway, so I'm not hugely interested, although I note that the abstract contains this:
Although the associated changes in the carbonate chemistry of surface and deep waters may adversely affect marine calcifying organisms2, 3, 4, current experiments do not always produce consistent results for a given species5.
Hoenisch et al is here and I must say it's fascinating stuff, but it seems to conclude that it's quite hard to use paleo records of the oceans of the past as analogues of current changes, because it's so hard to disentangle everything that's going on. Indeed, she concludes that on at least one consideration:
...the response of marine calcifiers to ocean acidification and seawater geochemistry during the [Permian–Triassic] and [Triassic–Jurassic] would arguably be closer to the modern than, for example, during the PETM (67). Improved estimates of past seawater–Mg/Ca composition are necessary to better evaluate all of this.
This all makes something of a nonsense of Roger Harrabin's report, which implied that the PETM was telling us something about the present.
So if I have misunderstood, it is in thinking that her work was relevant to what she said on air or to the question at hand, namely how much of a problem, if any, the oceans are facing. I've tweeted back to Prof Schmidt, asking her to justify her claims about corals, mussels and oysters. I will report back if and when I get a response.
Bishop Hill
Thanks to reader Anonymoose for pointing us to this paper, a study of a coral reef in the Western Pacific where pH is already at levels projected for global averages for the end of the century. It's flourishing. The authors also compare this finding to other naturally lower pH reefs:
Our across-site comparison reveals few commonalities among low-pH reefs studied to date.