Antinuclear

Australian news, and some related international items

Saying goodbye to coral reefs

If we continue to have warm summers like we had in ’16 and this year, the next one could wipe out the remaining coral. Now, I don’t want to sound doomsday, but that’s where we’re at right now. It’s still a wonderful place to visit. But if we continue on this trajectory it won’t be, very soon – within our lifetime. I think that this is the wake-up call that we need. If losing the Great Barrier Reef isn’t serious stuff, what is?

Farewelling coral reefs The Saturday Paper, Karen Middleton, 16 Sept 17  We hear much about trying to contain temperature rises to 2 degrees above pre-industrial levels. Why is that the magic number?

Ove Hoegh-Guldberg The 2-degree guardrail came out of the 2009 Copenhagen meeting. When you looked at how ecosystems were responding, you got into an unmanageable area at 2 degrees above the pre-industrial period, which was where the CO2 concentration had been stable for a long time. The trajectory we’re on today could raise temperatures by as much as 5 or 6 degrees on history.

One of the problems with 2 degrees is that generally people have the idea that it’s a guardrail. You go up to the edge of 2 degrees and look over it and see where you don’t want to go and it’s all very safe here. But it’s more like a slippery slope. Things get progressively worse until they become unmanageable. At the latest Conference of the Parties, the UNFCC [United Nations Framework Convention on Climate Change ] governing framework started to say, “well actually we want to keep things well below 2 degrees, and hopefully aim for 1.5 in the long term”.

KM And where are we now?

OHG We’re about a degree above the pre-industrial period.

KM So we’ve got half a degree’s leeway left.

OHG: To keep to that half a degree would be a massive decarbonisation of almost everything we do – energy, transport, food production and so on. Key to this is not just the amount of temperature change; it’s the system’s stability. If we don’t take care of fossil fuels we very quickly get into a situation where things change. Anything like that puts a lot of stress on biology but also on our economic systems. If you’re constantly having increasing temperatures and challenges then you’re not going to be able to build an economic system that will last 50 or 100 years……..

KM You predicted 20 years ago that we were going to be in a diabolical situation. Are you saying, “I told you so?”

OHG I wish I’d been wrong. A very simple model that I put together with people from the European Union showed what temperature was likely to do and we knew the temperature at which coral reefs got into trouble and they crossed each other around mid-century. I remember thinking at the time, “I hope this one’s wrong.” In the last couple of years we’ve had back-to-back bleaching events. Reefs have disappeared from many places – the Caribbean has been particularly hit hard. Corals have gone from maybe 50 to 60 per cent of the bottom of the ocean to less than 5 per cent in many places.

KM Is this irreversible?

OHG Under normal, non-climate-change circumstances, reefs might lose corals due to cyclones for example. And if they’re given 10 to 20 years, they’ll bounce back. But what’s been happening with these bleaching events, which are similar to cyclones in killing coral en masse, is they’re now coming faster and faster. There’s not enough time for reefs to bounce back……..

you have to say, “Where are those reefs that have the best chance of surviving a climate increase of 0.5 degrees?” The ocean isn’t heating up at the same rate in all places. There are some places where the currents have stalled, where it’s getting a lot hotter a lot quicker, like the equatorial Pacific, versus the coral triangle, which is this South-East Asian paradise for corals. The number of species there is something like three times that of Australia. So you start to go, “Oh, well if we’re going to preserve something we wouldn’t do it at the equator where it’s getting really, really hot – we should be going to South-East Asia.”

You do run into what appears to be triage, and I don’t think that’s the right word. I think it’s about another strategy being added onto the great things that are already going on in conservation. We will be releasing a list later this year and you have to ask the question: “What if the Great Barrier Reef’s not on it?” And it’s an interesting one………

KM How do you assess the current status of the Great Barrier Reef? How bad was the bleaching?

OHG The reef’s health has been rocky for some time. In 1998 we had 50 per cent of the reef bleached but only 10 per cent died. That’s 10 per cent of 40,000 square kilometres of coral – it’s still a large amount. Then it happened again in 2002 and then we had a bit of a break and then it came roaring back in 2016 and 2017, where not only much of the reef bleached but we lost almost 50 per cent of the corals over the last two years. If we continue to have warm summers like we had in ’16 and this year, the next one could wipe out the remaining coral. Now, I don’t want to sound doomsday, but that’s where we’re at right now. It’s still a wonderful place to visit. But if we continue on this trajectory it won’t be, very soon – within our lifetime. I think that this is the wake-up call that we need. If losing the Great Barrier Reef isn’t serious stuff, what is? https://www.thesaturdaypaper.com.au/news/environment/2017/09/16/farewelling-coral-reefs/15054840005215

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September 16, 2017 - Posted by | AUSTRALIA - NATIONAL, climate change - global warming

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