Core samples of the Great Barrier Reef going back 400 years show no bleaching before 1998. There was another event in 2002. In those events less than 20% of reefs were bleached in the affected zones. This year 95 per cent of the Great Barrier Reef’s northern reefs were rated as severely bleached. Only 4 out of 520 reefs surveyed, less than one per cent, were found to be unaffected by bleaching.
The bleaching is destroying the northern sector of the Reef as we watch.
This is what a really healthy reef looks like:
The SMH has some startling images of what’s been happening.
Terry Hughes, a professor at James Cook University and convener of the National Coral Bleaching Taskforce, led the survey team last week using planes and helicopters. He says the situation is now critical:
- “This will change the Great Barrier Reef forever,” Professor Hughes told 7.30.
“We’re seeing huge levels of bleaching in the northern thousand-kilometre stretch of the Great Barrier Reef.”
Of the 520 reefs he surveyed, only four showed no evidence of bleaching.
From Cairns to the Torres Strait, the once colourful ribbons of reef are a ghostly white.
He says it’s too early to tell, but he thinks half of the affected reefs will die. For the rest, he told the 7.30 Report, we are looking at a 10-year recovery period.
Some reefs have been bleached twice and possibly three times since 2014. With current temperature trends we can expect more bleaching within the next 10 years.
Professor Justin Marshall from the University of Queensland:
- The prognosis just gets worse and worse as more of these global events occur. I guess what upsets me the most is that we are literally stealing the future from our children. I’m going to be dead within 30 years. I probably won’t see the possible end of the Great Barrier Reef. But it’s possible that my grandchildren will and that really upsets me.
Environment Minister Greg Hunt wasn’t available for on camera interview, but talked up the positive. The reef was 2300 kilometres long, the bottom 75% of it was pretty much OK. He’s been saying that the Australian and Queensland governments are investing around $2 billion over the next decade to protect the Great Barrier Reef. They will monitor what happens, they are working on water quality, we are meeting and beating our targets, etc, etc.
The scientists want to see action on climate change. To them Australia has not yet joined the group of countries that are taking the Paris conference last December seriously. Hughes told The World Today:
- The $2 billion figure is much bandied around. It’s basically the operating budget for all the agencies that have anything remotely to do with the Great Barrier Reef.
So the Minister hasn’t yet announced a significant response other than paying for more surveys of dead corals.
I don’t think many people would regard that as an adequate response.
Really in the longer term what’s needed is a change in policy around Australia’s greenhouse gas emissions that would be favourable to the Great Barrier Reef.
So many people would regard issuing a permit for a new coal mine in Queensland for the next 60 years as a profound policy failure for the Great Barrier Reef.
So certainly the science community is hoping that the Federal Government will look again at our emissions trajectory which is trending upwards, and also putting back the price on carbon, and at not cutting the renewable energy target by 30 per cent.
The Queensland government has called on Turnbull to show as much interest as Abbott and at least visit the Reef.
In The Folly of two degrees in December 2014 I quoted David Spratt:
- It has been shown that “preserving more than 10 per cent of coral reefs worldwide would require limiting warming to below +1.5°C (atmosphere–ocean general circulation models (AOGCMs) range: 1.3–1.8°C) relative to pre-industrial levels”.
I believe the Great Barrier Reef generates about 70,000 jobs and $5 billion each year in revenue. As the waves roll in and we look forward to surfing, remember the Irukandji jellyfish is finding climate change quite congenial!
Update: Further reports on 7 April and 11 April update the damage. The most severe bleaching is north of Cairns, with patchy bleaching almost as far south as Mackay, with “reasonable” levels of bleaching down to Great Keppel Island, near Rockhampton.
It seems at tourist centres there are “reefs that are still in good condition.”
The 95% figure relates to reefs between Cairns and Papua New Guinea.
Cyclone Winston out in the Coral Sea was responsible for bringing cooler water to the central and southern sections of the reef. Also there were higher tides around Mackay, which brought in cooler water.
During aerial surveys, each reef is given a score from 0, indicating no bleaching, to 4, indicating that more than 60% of the corals are bleached.
In 1998 and 2002 fewer than 200 reefs were assigned categories 3 an 4. By 7 April 2016 the number was 450.
See also new post, Coral reef resilience.