[Coral-List] Coral bleaching and ocean acidification

[Lee Kump]

Dear Tom,

Although I agree with much of what you say about warming and
bleaching, you are wrong in assuming that acidification will take
thousands of years to develop. In fact, just the opposite: surface
water acidification is immediate, because the surface ocean is
in intimate contact with the atmosphere, and atmospheric pCO2
is increasing. This can be easily shown both theoretically and
through observation: see for example the review article
by Orr et al. (2005; Nature 437: 681-686) or a nice wikipedia
site: http://en.wikipedia.org/wiki/Ocean_acidification.

Rapid acidification such as what is occurring now affects surface
waters first, then deep waters, where carbonate dissolution occurs.
Slower additions of CO2, such as those that led to the high atmospheric
CO2 levels of the Cretaceous (100 million years ago) occurred at
such a slow rate that geological processes (e.g., weathering of the
continents) were able to keep the ocean surface waters supersaturated
despite high CO2. Rates matter, as you say, but not in the way you
suggest.

Cheers,

Lee

On Feb 11, 2009, at 7:05 PM, Thomas Goreau wrote:

> Dear Steve,
>
> Don't let these flat earth neanderthals spin this fable without
> looking at the real data. First, the fact that CO2 is a greenhouse gas
> is the result of a fundamental physical law, not a hypothesis to be
> tested. But the details of how fast it warms up depends on the
> dynamics of heat flow in the entire ocean-atmosphere-ice-biosphere
> system, which is very complex with many time scales, the key ones
> taking thousands of years. We have tabulated all of the satellite sea
> surface temperature data for every major coral reef area since 1982,
> and the correlation between bleaching and high temperatures are
> crystal clear. In fact the Goreau-Hayes HotSpot method has
> successfully predicted all major bleaching events since we developed
> it in 1990. We have never received one penny of grant money for this
> work, in fact it was largely suppressed for political reasons, because
> the flat earthers were in charge of the budget. Hopefully that will
> change.
>
> Best wishes,
> Tom
>
> On Feb 11, 2009, at 2:16 PM, Steve Mussman wrote:
>
>>
>> I am constantly in contact with skeptics of anthropologic climate
>> change.I have studied this issue for many years, but as an amateur
>> naturalist, not a scientist.
>>
>> Would you mind answering a few questions about your posting?
>>
>> Are you saying that you find a direct link between tropical surface
>> water temperature increases and atmospheric CO2 levels?
>>
>> If I understand you correctly, you are expressing the concern that
>> we must stabilize CO2 levels in order to control ocean water
>> temperatures and therefore, protect the reef systems from mass
>> bleaching episodes.
>>
>> I am a diver and environmentalist with a particular interest in
>> coral reef ecology. I live in the Atlanta area and often discuss
>> these issues with many divers who think that I'm totally off base by
>> insisting that we are directly affecting our climate by ignoring
>> calls for controls on CO2 and other greenhouse gases. I am told that
>> I have fallen for the hoax that is being perpetrated by scientists
>> who are simply alarmists attempting to increase their grant money.
>>
>> Regards,
>>  Steve
>> sealab at earthlink.net
>>
>> -----Original Message-----
>>> From: Thomas Goreau <goreau at bestweb.net>
>>> Sent: Feb 11, 2009 11:02 AM
>>> To: coral-list coral-list <coral-list at coral.aoml.noaa.gov>
>>> Subject: [Coral-List] Coral bleaching and ocean acidification
>>>
>>> Ocean acidification has become the latest bandwagon fad to hit coral
>>> reefs, and is being claimed as a "shocking new revelation" that will
>>> kill reefs and dissolve the evidence.
>>>
>>> In fact there is nothing new about knowledge of the problem, all
>>> carbonate chemists have always known that CO2 is the major acid in
>>> the
>>> atmosphere and so its concentration controls the equilibrium pH of
>>> the
>>> ocean, along with the equilibrium with solid limestone minerals.  
>>> More
>>> than 30 years ago at Harvard we would make undergraduate  
>>> geochemistry
>>> students routinely calculate the equilibrium decline in ocean pH for
>>> doubling of CO2 as a homework problem! It is long known that periods
>>> in the past with no coral reefs or limestone sediments were  
>>> caused by
>>> acidification, either due to higher atmospheric CO2, or more often,
>>> to
>>> changes in ocean circulation that resulted in CO2 build up in deep
>>> waters from decomposition of organic matter in anoxic basins.
>>>
>>> But the fact is that these changes take thousands of years to
>>> develop,
>>> because they depend on the circulation time of the ocean and  
>>> reaction
>>> rates with deep sea sediments. The increase in direct surface
>>> temperature is a far more serious and immediate threat to reefs than
>>> acidification. Acidification will only dissolve the dead skeletons
>>> centuries to millenia after high temperatures kill the corals, so
>>> focusing on acidification amounts to a red herring and effectively
>>> ignores a far larger and more immediate problem.
>>>
>>> Recently “Declining coral calcification on the Great Barrier
>>> Reef” (De'ath, Lough, Fabricius, 2009, SCIENCE, 2 January, p. 116)
>>> shows field data convincingly indicating a strong negative
>>> relationship between rising temperatures and coral growth rates, and
>>> attributes decreasing coral growth in the last two decades to
>>> declining ocean pH caused by rising atmospheric CO2. Major flaws  
>>> with
>>> this hypothesis are not discussed.
>>>
>>> 1) Coral bleaching is never mentioned. Yet there have been many
>>> episodes of mass coral bleaching in the Great Barrier Reef in the
>>> last
>>> two decades, and these are accurately predicted from high sea  
>>> surface
>>> temperatures (1, 2). Bleached corals stop skeletal growth (3)  
>>> even if
>>> temperatures are not high enough to kill them. This is because coral
>>> calcification as a function of temperature has a temperature optimum
>>> that is only slightly below the bleaching and death thresholds (4).
>>>
>>> 2) Tropical surface waters are not in equilibrium with atmospheric
>>> CO2
>>> due to the strong inverse relationship of CO2 solubility with
>>> temperature. As a result tropical surface oceans have partial
>>> pressures of CO2 above equilibrium with the atmosphere, and are a
>>> SOURCE, NOT A SINK, of atmospheric CO2 (5). CO2 dissolves in cold
>>> polar waters, where it takes about a thousand years to upwell  
>>> back to
>>> surface waters. As a result of this natural ocean CO2 cycle,  
>>> tropical
>>> surface waters will be the LAST part of the oceans where limestone
>>> becomes undersaturated. Furthermore calcium carbonates are anomalous
>>> minerals that become less soluble at high temperatures, not more
>>> soluble like almost all other minerals (6). Therefore the alarm  
>>> about
>>> acidification effects on coral reefs is based on fundamental
>>> misunderstanding of the CO2 cycle in tropical surface waters.  
>>> This is
>>> not to say that it is not an important long-term problem, but only
>>> that it is trivial compared to bleaching as a source of coral
>>> mortality and growth decline.
>>>
>>> It is therefore likely that the decline in coral calcification
>>> reported in the Science paper is due to repeated temperatures above
>>> bleaching thresholds, which has happened increasingly in the past  
>>> two
>>> decades (2), and that impacts of ocean acidity dissolving limestone
>>> will only take place long after the corals are directly killed by
>>> high
>>> temperature.
>>>
>>> There is no question that we need to stabilize CO2 at safe levels
>>> immediately because IPCC has seriously underestimated the  
>>> sensitivity
>>> of temperature and sea level to CO2 as shown by the paleoclimatic
>>> record (7). But that is needed in order to take care of the  
>>> immediate
>>> temperature problem, not the long term acidification, at least as  
>>> far
>>> as coral reefs are concerned.
>>>
>>> If we take care of the CO2 stabilization in time to solve the
>>> bleaching problem, we will not only save coral reefs from mass
>>> extinction, we will automatically solve the ocean acidification
>>> problem. If we focus on solving the acidification problem first, it
>>> will come far too late to save coral reefs.
>>>
>>> 1) T. J. Goreau, & R. L. Hayes, 1994, Coral bleaching and ocean "hot
>>> spots", Ambio, 23: 176-180
>>>
>>> 2) T.J. Goreau, & R.L. Hayes, 2005, Global coral reef bleaching and
>>> sea surface temperature trends from satellite-derived Hotspot
>>> analysis, World Resource Review, 17: 254-293
>>>
>>> 3) T. J. Goreau & A. H. Macfarlane, 1990, Reduced growth rate of
>>> Montastrea annularis following the 1987-1988 coral bleaching event,
>>> Coral Reefs, 8: 211-215
>>>
>>> 4) C. Clausen, 1971, p. 246-269 in Experimental Coelenterate  
>>> Biology,
>>> H. M. Lenhoff and L. Muscatine (Eds.), University of Hawaii Press,
>>> Honolulu
>>>
>>> 5) T. Takahashi, S. C. Sutherland, C. Sweeney, A. Poisson, N. Metzl,
>>> B. Tilbrook, N. Bates, R. Wanninkhof, R. A. Feely, C. Sabine, J.
>>> Olafsson, & Y. Nojiri, 2002, Global sea–air CO2 flux based on
>>> climatological surface ocean pCO2, and seasonal biological and
>>> temperature effects, Deep Sea Research Part II: Topical Studies in
>>> Oceanography, 49: 1601-1622
>>>
>>> 6) R. M. Garrels & C. R. Christ, 1965, Solutions, minerals, and
>>> equilibria, 450 p., Harper & Row, New York.
>>>
>>> 7) T. J. Goreau, 1990, Balancing Atmospheric CO2, Ambio, 19: 230-236
>>>
>>> Thomas J. Goreau, PhD
>>> President, Global Coral Reef Alliance
>>> Coordinator, United Nations Commission on Sustainable Development
>>> Partnership in New Technologies for Small Island Developing States
>>> 37 Pleasant Street, Cambridge MA 02139
>>> 617-864-4226
>>> goreau at bestweb.net
>>> http://www.globalcoral.org
>>>
>>> _______________________________________________
>>> Coral-List mailing list
>>> Coral-List at coral.aoml.noaa.gov
>>> http://coral.aoml.noaa.gov/mailman/listinfo/coral-list
>>
>
> Thomas J. Goreau, PhD
> President, Global Coral Reef Alliance
> Coordinator, United Nations Commission on Sustainable Development
> Partnership in New Technologies for Small Island Developing States
> 37 Pleasant Street, Cambridge MA 02139
> 617-864-4226
> goreau at bestweb.net
> http://www.globalcoral.org
>
> _______________________________________________
> Coral-List mailing list
> Coral-List at coral.aoml.noaa.gov
> http://coral.aoml.noaa.gov/mailman/listinfo/coral-list