More Coral Reef Shenanigans

How do things like this get published in peer-reviewed journals? Doesn’t anybody ever check the work? 

The January 2, 2009 issue of Science featured a paper, Declining Coral Calcification on the Great Barrier Reef, by Glenn De’ath, Janice M. Lough, Katharina E. Fabricius. This is from the abstract: 

Reef-building corals are under increasing physiological stress from a changing climate and ocean absorption of increasing atmospheric carbon dioxide. We investigated 328 colonies of massive Porites corals from 69 reefs of the Great Barrier Reef (GBR) in Australia. Their skeletal records show that throughout the GBR, calcification has declined by 14.2% since 1990, predominantly because extension (linear growth) has declined by 13.3%. The data suggest that such a severe and sudden decline in calcification is unprecedented in at least the past 400 years. 

I have not purchased the article and my free membership to the AAAS does not grant access to it; but I did find the database that appears to go with De’ath et al., 2009 in the NOAA Paleoclimatology library: LINK 

Well… I downloaded the data to Excel and I calculated an annual average calcification rate for the 59 cores that are represented in the data set. This is what I came up with… 

Great Barrier Reef Calcification Rate (after De'ath et al., 2009)

There is no decline in the calcification rate of the Great Barrier Reef apparent in these data. The only thing that even remotely looks like a decline is caused by the last point in the series. The data before 1670 and after 1981 are highly erratic; with wide annual swings in calcification rates. These are also periods in which very few cores (<10) are available. 

It is “cherry-picking” of the highest order, if that last data point really is the basis of this claim: “Their skeletal records show that throughout the GBR, calcification has declined by 14.2% since 1990, predominantly because extension (linear growth) has declined by 13.3%. The data suggest that such a severe and sudden decline in calcification is unprecedented in at least the past 400 years.” 

Over the last 400+ years the Earth’s climate has warmed ~0.6°, mean sea level has risen by about 9 inches and the atmosphere has become about 100 ppmv more enriched with CO2; and the Great Barrier Reef has responded by steadily growing faster. 

1. Rising Temperature: The Great Barrier Reef likes the warm-up since the depths of the Little Ice Age…

 

2. Rising Sea Level: The Great Barrier Reef likes the slight sea level rise since the depths of the Little Ice Age… 

 

3. Rising Atmospheric CO2 Concentrations: The Great Barrier Reef likes the increase in CO2 levels since the depths of the Little Ice Age… 

 

 

A new paper in Geology (Ries et al., 2009) details the results of experimentally subjecting 18 carbonate shell building species to high CO2 levels. Most of them liked more CO2; particularly Coralline Red Algae and Temperate Coral… 

Coralline red algae calcification response to increased atmospheric CO2 (modified after Ries eta la., 2009)

Temperate coral calcification response to increased atmospheric CO2 (modified after Ries et al., 2009).

Neither coral species experienced negative effects to calcification rates at CO2 levels below 1,000 to 2,000 ppmv. The study reared the various species in experimental sea water using 4 different CO2 and aragonite saturation scenarios. But the study assumed a linear decline in aragonite saturation with increasing CO2. Higher CO2 can reduce aragonite saturation; but it usually doesn’t… 

CO2 vs. Aragonite saturation depth (from Feely et al., 2004)

From Feely et al., 2004 

So, coral building critters would probably take 3,000 ppmv CO2 in stride, just by making more limestone… Kind of like they did during the Cretaceous… 

East Texas Stratigraphic Column and Creatceous CO2

 Reef data from: 

De’ath, G., J.M. Lough, and K.E. Fabricius. 2009.
Declining coral calcification on the Great Barrier Reef.
Science, Vol. 323, pp. 116 – 119, 2 January 2009. 

Lough, J.M. and D.J. Barnes, 2000.
Environmental controls on growth of the massive coral Porites.
Journal of Experimental Marine Biology and Ecology, 245: 225-243. 

Lough, J.M. and D.J. Barnes, 1997.
Several centuries of variation in skeletal extension, density and calcification in massive Porites colonies from the Great Barrier Reef: a proxy for seawater temperature and a background of variability against
which to identify unnatural change.
Journal of Experimental Marine Biology and Ecology, 211: 29-67. 

Chalker, B.E. and D.J. Barnes, 1990.
Gamma densitometry for the measurement of coral skeletal density.
Coral Reefs, 4: 95-100. 

Temperature data from: 

Moberg, A., D.M. Sonechkin, K. Holmgren, N.M. Datsenko and W. Karlén. 2005.
Highly variable Northern Hemisphere temperatures reconstructed from low-and high-resolution proxy data.
Nature, Vol. 433, No. 7026, pp. 613-617, 10 February 2005. 

University of Alabama, Hunstville 

Sea Level data from: 

“Recent global sea level acceleration started over 200 years ago?”, Jevrejeva, S., J. C. Moore, A. Grinsted, and P. L. Woodworth (2008), Geophys. Res. Lett., 35, L08715, doi:10.1029/2008GL033611. 

CO2 data from: 

D.M. Etheridge, L.P. Steele, R.L. Langenfelds, R.J. Francey, J.-M. Barnola and V.I. Morgan. 1998. Historical CO2 records from the Law Dome DE08, DE08-2, and DSS ice cores. In Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A. 

Dr. Pieter Tans, NOAA/ESRL (www.esrl.noaa.gov/gmd/ccgg/trends) 

  

Other references: 

 

Justin B. Ries, Anne L. Cohen, and Daniel C. McCorkle
Marine calcifiers exhibit mixed responses to CO₂-induced ocean acidification
Geology 2009 37: 1131-1134.

Feely RA, et al.(2004) 
Impact of anthropogenic CO2 on the CaCO3 system in the oceans.
Science 305:362–366.