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Comments on: First-time Bleaching in Ningaloo, Western Australia http://www.climateshifts.org/?p=6556 Science, climate change, coral reefs and the environment Mon, 31 Mar 2014 21:57:00 +0000 hourly 1 http://wordpress.org/?v=3.8.25 By: OveHG http://www.climateshifts.org/?p=6556#comment-1451 Mon, 09 May 2011 00:58:39 +0000 http://www.climateshifts.org/?p=6556#comment-1451 Thanks Thomas, I neglected to mention that key facts about the Lough and Barnes paper. You are absolutely correct … the data in the paper that Marc H clings to only goes up to 1982-1991 (with the growth trend ending in 1982). Pity Marc is picking the wrong cherries – doesn’t help the credibility of his arguments!

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By: Thomas Moore http://www.climateshifts.org/?p=6556#comment-1448 Mon, 09 May 2011 00:31:39 +0000 http://www.climateshifts.org/?p=6556#comment-1448 Lough et al (see link below)show the current decline in calcification is not unprecedented even in the last 100 years

Actually, it doesn’t. The coral data from Lough’s paper was collected in the early 1980′s and ends between 1982-1991. The figure and relevant text you cite on page 61 ends in 1982, prior to the onset of mass bleaching events. There’s a more recent paper by De’ath covering the entire record and recent decades (up until 2005). Compare Figure 8 in Lough’s paper (published in 1997 with 35 corals up until 1982) with Figure 2a in De’aths paper (published in 2009 with 326 corals up until 2005). To quote De’ath: “The data suggest that such a severe and
sudden decline in calcification is unprecedented in at least the past 400 years.” Again, there is no observational bias – your bias here is that you are citing a paper that’s 14 years old and ignoring more recent literature. Note that Lough is a co-author on both papers.

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By: OveHG http://www.climateshifts.org/?p=6556#comment-1447 Sun, 08 May 2011 23:45:11 +0000 http://www.climateshifts.org/?p=6556#comment-1447 The reason for the high calcification and growth rates of Porites during this period? Exceptional increases in sea temperature. The only problem is that the relationship between calcification and growth is optimal around 1°C below today’s sea temperatures, leading to speculation that the 15% decrease in calcification since 1990 is properly a combination of decreasing carbonate ion concentrations and increasing sea temperature (beyond this optimal temperature).

Here is a more up-to-date reference which discusses the previous assessment by Lough and Barnes (1997).

Note the rather well-published group of authors!

Kleypas, J.A., Buddemeier, R.W., Eakin, C.M., Gattuso, J.P., Guinotte, J., Hoegh-Guldberg, O., Iglesias-Prieto, R., Jokiel, P.L., Langdon, C., and Skirving, W., 2005, Comment on” Coral reef calcification and climate change: the effect of ocean warming”: Geophysical Research Letters, v. 32, p. L08601.

I hope that this helps you understand the subtleties of this issue, Mark H.

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By: MarcH http://www.climateshifts.org/?p=6556#comment-1446 Sun, 08 May 2011 23:32:07 +0000 http://www.climateshifts.org/?p=6556#comment-1446 By the way Thomas, Lough et al (see link below)show the current decline in calcification is not unprecedented even in the last 100 years. With several other periods with low Cal rates going back to the 1400s. Indeed they speculate (page 61):
“The majority of the 35 very large colonies of Porites analysed here show a decline in calcification in recent decades. However, a decline in calcification equivalent to the recent decline occurred earlier this century and much greater declines occurred in the 18th and 19th centuries (Fig. 8~). Analyses of annual density banding provided here indicate that the 20th century has witnessed the second highest period of above average calcification in the past 237 years. The observed decline in coral growth
in recent decades may be, simply, a return to more “normal” conditions.”

Several centuries of variation in skeletal extension, density and calcification in massive Porites colonies from the GreatBarrier Reef: A proxy for seawater terature empand a background of variability against which to identify unnatural change doi:10.1016/S0022-0981(96)02710-4

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By: Thomas Moore http://www.climateshifts.org/?p=6556#comment-1445 Sun, 08 May 2011 23:31:52 +0000 http://www.climateshifts.org/?p=6556#comment-1445 I think you are misled – there is no paradigm here. I cited the paper to show a point: two cores from one location show signs of mortality (one attributed to temperature, one attributed to a low salinity flood event) against 326 cores from the GBR. Both mortality events were over 200 years ago. Again, where is the evidence for El Nino related episodic mortality on the GBR prior to 1990? There is no lack of observational history, there is no observational bias. If this is the only trace of it in the geological record, you’d be hard pushed not to argue that coral bleaching was not a widespread phenomenon in decades previous to 1990.

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By: MarcH http://www.climateshifts.org/?p=6556#comment-1443 Sun, 08 May 2011 23:13:23 +0000 http://www.climateshifts.org/?p=6556#comment-1443 Thomas,
Your comment above just broke your argument. We were looking for signs of mass bleaching prior to 1990 (recall” Where’s the evidence for this El Nino related episodic mortality on the GBR prior to 1990?”) and you found it well done!

“Sure there’s (some) evidence of partial mortality related to historical stress on the GBR (DOI: 10.1007/s00338-003-0304-7), but that’s not direct evidence of ‘bleaching’, and only two events exist: 1782–85 and 1817.”

So two more event to add to the list. Amazing what you can find if you bother to look.
Talk about being stuck in a paradigm trap.

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By: OveHG http://www.climateshifts.org/?p=6556#comment-1439 Sun, 08 May 2011 21:16:33 +0000 http://www.climateshifts.org/?p=6556#comment-1439 Thank you Thomas for the rational and evidence-based response. Personally, I am surprised that people with limited expertise and understanding are so loud about these issues (e.g. Bolt and his mates). I really wonder what motivates them?

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By: Thomas Moore http://www.climateshifts.org/?p=6556#comment-1438 Sun, 08 May 2011 11:42:41 +0000 http://www.climateshifts.org/?p=6556#comment-1438 When is the coral research community in Australia going to conduct a similar study (to the one cited above Yu et al 2006) on the GBR? If it’s been done, please pass on the DOI.

You mean coral cores from the GBR not showing any signs of historical mortality? Go look at one of about two dozen papers from AIMS – here’s one with 326 corals that spans most of the last century. There’s no observational bias.

In the meantime the ENSO history of eastern Australia and close association with mass coral bleaching events (see for instance Figure 9 from Quaternary Science Reviews 19 (2000) 45-64 “New views of tropical paleoclimates from corals” M.K. Gagan et al. doi:10.1016/S0277-3791(99)00054-2) provides plenty of prospective years with an increased likelihood of mass bleaching events on the GBR, particularly years with strong ENSO events.

Pity the aqualung wasn’t around so we could have got a report.

No need for the aqualung. Coral bleaching causes declines in growth and coral mortality. If there was evidence of bleaching, it’d be there in the geological record. There is no record of historical bleaching on the Great Barrier Reef – plenty of people have gone looking for it, and plenty of cores show no evidence of declines in growth rates or evidence of mortality. Sure there’s (some) evidence of partial mortality related to historical stress on the GBR (DOI: 10.1007/s00338-003-0304-7), but that’s not direct evidence of ‘bleaching’, and only two events exist: 1782–85 and 1817. It’s not observational bias, either.

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By: MarcH http://www.climateshifts.org/?p=6556#comment-1437 Sun, 08 May 2011 11:25:53 +0000 http://www.climateshifts.org/?p=6556#comment-1437 See earlier comments regarding Observational bias.

When is the coral research community in Australia going to conduct a similar study (to the one cited above Yu et al 2006) on the GBR? If it’s been done, please pass on the DOI.

In the meantime the ENSO history of eastern Australia and close association with mass coral bleaching events (see for instance Figure 9 from Quaternary Science Reviews 19 (2000) 45-64 “New views of tropical paleoclimates from corals” M.K. Gagan et al. doi:10.1016/S0277-3791(99)00054-2) provides plenty of prospective years with an increased likelihood of mass bleaching events on the GBR, particularly years with strong ENSO events. Pity the aqualung wasn’t around so we could have got a report.

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By: Thomas Moore http://www.climateshifts.org/?p=6556#comment-1436 Sun, 08 May 2011 07:59:13 +0000 http://www.climateshifts.org/?p=6556#comment-1436 Yep, South China Sea is a marginal environment for coral reefs. Where’s the evidence for this El Nino related episodic mortality on the GBR prior to 1990?

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