Quote:I read a couple news articles from the winter of 2015 (November time frame) which was discussing the bleaching in Hawaii.  The fact is that while El Nino can be one factor, it has only been exaserbating the issue.

 

Now I'm no marine biologist, but I did watch the PBS NOVA episode on Coral Bleaching a few years back.  A slight increase in temperature causes bleaching.  The prolonged raised temperature is what eventually kills off the coral, as the bleaching is a sign that the photosynthesis isn't happening.

 

So while El Nino's can trigger an event, the fact that temperatures overall have been rising is creating a bigger problem.  

 

And the idea the farm run off is causing the bleaching, again, is just silly.  Unless you want to provide a source that states your claim that farm run off is the big factor of coral bleaching, I'm just not gonna believe that to be the issue here.

 

I rechecked that and you are right. Runoff can kill corals, but does not cause bleaching.


 

Apparently bleaching is predominantly caused by rapid temperature changes.
 Excess UV (lack of clouds) is the other major cause. Global warming is a slow change, but may make bleaching more likely. That's especially true during El Nino events like this year's. I still doubt the fraction of a degree warming caused by Global Warming is responsible, we're not talking about a lot of warming in the tropics. Corals have been around since before the dinosaurs, and the planet has been much warmer than the present for most of that time.

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