Transcript
Mark Eakin says they will be monitoring the temperature of the World's oceans carefully over the coming months to confirm that the global coral bleaching event has indeed ended but he warned that high temperatures could still persist in some areas.
MARK EAKIN: This event it's broken a number of records. Number one, it is the most long-lasting bleaching event we have ever had. Number two, it is the most widespread and number three, and we are still working on the details, it is probably the most damaging. Certainly in many areas it was the most damaging and a part of that was because since this was a multi-year event you had a number of areas that bleached more than once during this event and so that return of bleaching so quickly, sometimes one year right after the next, has caused a lot of damage.
KOROI HAWKINS: Just for our listeners, bleaching is when the pods which make up or build the coral die of because water conditions are too hot or too acidic or not suitable for their life, is that right?
ME: That's right but for these large, widespread events that we are talking about, it is simply driven by temperatures that are too high.
KH: You're saying now that it is likely that it is, I mean you are still looking at the science of this I understand, what determines that a coral bleaching event ends?
ME: Well it's really a matter of, since this is a global event, looking to see if there is widespread bleaching in all three major ocean basins that contain coral reefs. So, the Indian Ocean, the Pacific Ocean and the Atlantic/Caribbean basins each have to have widespread bleaching for this to be a global event. There was no widespread bleaching in the Indian Ocean, there was one place where there was some severe bleaching in southwestern Madagascar but elsewhere in the Indian Ocean the bleaching was relatively mild and only a few reports. So as far as a global event, that's what has come to an end. We may see bleaching in the northern hemisphere, both the north Pacific and the Caribbean later this year but at least as far as a global event, this has come to a conclusion.
KH: And we're talking about climate naysayers and people who don't believe the changing climate is having a negative impact, is that something that shows that things can get better and not worse or is this just unrelated to that and more related to the climate and the weather, El Nino and those sort of events?
ME: What we have seen is that during this event it clearly was driven by climate change where the warming had brought the temperature up so it didn't require a huge El Nino to institute this bleaching, in fact it started more than a year before the El Nino kicked in. Instead what we are looking at is a situation where the temperatures are so high that rather than requiring a big shove like a big El Nino, it is only a gentle nudge that is required to push the corals over their limits. This is clearly something that has been caused by global warming but we are right now seeing a bit of a respite between this event and the next.
KH: And this is significant and important because corals are the foundations of the marine ecosystems aren't they?
ME: Absolutely. At least in tropical waters these are hugely important organisms that are driving an ecosystem that is the most diverse on the planet. Equal or even more diverse than what is seen in rain forests. So this is a system which provides a great deal for humans around the world, over a half a billion, perhaps a billion people, are reliant on coral reefs, so for all of these people this is a very important problem that we are seeing.
KH: What's the worst case scenario here, if this comes a more permanent event?
ME: This is the concern we have, how long is it going to be before we start seeing recurrent bleaching, either annual bleaching or even before then, perhaps twice per decade is more than enough to just lead to a severe disruption of these ecosystems.
KH: There is also this side issue, there is some talk of about bleaching resistant strains of coral, is there any significance in that in terms of maybe evolution or the future in a world where bleaching is more common?
ME: Well there absolutely has been some work going on to try and develop corals that are going to be more resistant but the problem is that we are seeing so much warming happen so fast that the corals just can't keep up. So that sort of work is very valuable. It is going to be expensive. It's going to require efforts to figure out how to scale it up to the large scale of the losses we have been seeing but it is very important because we need to be doing everything we can to help these ecosystems survive.
