[Coral-List] Basic Question. Simple Answer ?

John Meaker kr4ah at empery.sss.org
Sat Jul 24 11:42:53 EDT 2004

On Fri, 23 Jul 2004, Mark Eakin wrote:

> While air temperatures rose dramatically in Greenland at the end of the
> Younger Dryas, it is unlikely that tropical oceans warmed anywhere near
> that much.

	Do you mean that the warming trend was not at great in terms of
number of degrees of temperature change or that the change had less impact
on the ecosystem?  Does it not take a smaller temperature change in water
to impact the marine environment than air for a terrestrial environment?  

	Also, many scientists believe that North Atlantic Deep Water
(NADW) circulation was a large part of the reason for those dramatic
temperature changes.  If the North Atlantic limb of the Conveyor did 
indeed shut down, would it not have had a major impact on tropical oceans?  

	Additionally, the mid holocene warm period actually saw warmer
global temperatures than we are currently experiencing.  Then, of course
there was the "Little Ice Age."  My point is that there have been periods
of tremendous volitility in climate in the earth's history.  We currently
(for the last 3,000 or so years) have been experiencing an unusual period
of stability.  This is extremely unusual and I doubt that is normal, at 
least in the long term scheme of things.  

	We know that the recent stability in climate has been extremely
favorable for us and that nature is capable of throwing some really nasty
climatological changes our way. Large glacial melts, dramatic eustatic 
seal level rises, meltwater pulses causing salinity changes and other 
effects are not only possible but a normal part of global change.  I am 
not trying to say that they are good for the ecology (or for mankind 
either) but that they are "normal" in some sense.  

> More important were changes in the area of warmth in the tropics.  That
> was also an increase from cold (glacial) conditions to warm
> (interglacial).  Your question regarding global warming is a further
> increase in interglacial temperatures.

	But (so far, at least) not as warm as the Mid-Holocene?

> If corals were not under a wide range of other anthropogenic stresses,  
> then the warming would probably be less of an issue.  The temperature  
> problem is really compounded by the additive and synergistic effects of  
> other stress imposed on the corals at the same time as the warming.

	How about the additive stresses of a meltwater pulse?  How did the 
interplay of change in salinity, temperature, sea level and sediment 
loading affect the coral ecosystem?  

> Corals are not likely to go extinct.  However, it can take a long time  
> for coral reef ecosystems to recover from severe stresses like those we  
> are likely to see in the next century.

	Just because dramatic global global change is natural does not 
mean it isn't devistating.  Natural disasters in the past have virtually 
wiped out life on Earth as it was known at the time.  I believe that the 
difference here is that manking can forsee the effect that he has.  The 
larger question is, "Is mankind willing to change to protect the 
environment and not kill himself off?"  

	John Meaker

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