The Great Barrier Reef RECOVERS FROM BLEACHING EVENTS!
• Guest post •
— by John McLean, in Australia
New Zealand’s TV One kept up its tradition of climate misinformation last night (8 Nov), this time about the state of the Great Barrier Reef (GBR).
I have good contacts in North Queensland: a diver with over 50 years’ experience and a professor at James Cook University in Townsville. As it happens, I myself have also undertaken an in-depth study into sea temperatures along the GBR, so I can speak with some authority.
Here’s the more complete picture about coral bleaching so that NZ readers might compare it with what TV One told them.
- The same corals that grow on the GBR grow very well in even warmer waters off PNG and Indonesia.
- Radiation from carbon dioxide penetrates into the ocean just a few microns (thousandths of a millimetre) where the energy contributes to evaporation; it can’t heat the body of water.
- Heat from the air doesn’t penetrate far into the water either unless there are waves to increase the amount of water in contact with the air and to drag down any water warmed by that contact. (Waves will also play a big part in cooling the water if it’s warmer than the air, by exposure and evaporation.)
- The GBR, like most of the ocean to at least 30 degrees away from the equator, warms from solar radiation, i.e., the sun. Most of that energy is absorbed in the first 10 metres of ocean and it might even be less if the water is murky.
- Bleaching requires a combination of circumstances: (a) clear skies to get that sunlight, (b) the absence of cooling sea breezes and (c) shallow water (so that the water is easily heated).
- For the GBR the combination of circumstances is more common during El Nino events or during weak monsoons that have periods of clear skies, but it can occur in any summer.
- Humans do not influence cloud cover, wind or the depth of the ocean therefore it cannot honestly be claimed that human activity has any influence on reef bleaching.
- The GBR has been extensively monitored only since the mid-1990s so claims that bleaching is a new phenomenon are suspect. Bleaching was reported back in 1927* and there’s anecdotal evidence of at least small-scale bleaching back in the 1950s. No-one made a big fuss about it then and no-one looked to see how much was bleached. It might have happened for thousands of years — perhaps even to the five old reefs on which the GBR now sits.
- The GBR is on an eastern continental shelf, like many reefs around the world. This means the currents caused by the Earth’s rotation will bring nutrients to the reef. On this basis it would be extremely unusual not to have a reef there.
- And coral does recover from bleaching, as numerous reports testify, for example …
From the second link:
Tourists also appear on the video saying they can’t believe how beautiful the Reef is after what they’d been told about its imminent demise.
TV One was implying last night that the Great Barrier Reef’s death is imminent. The media has a huge influence over public opinion but it’s not unreasonable to expect them to be honest.
*Yonge, C.M. and Nicholls (1931), G. Barrier Reef Expedition, Sci. Repts., Brit. Mus., 1, 135
Views: 681
During an El Nino the sea level falls in the Eastern Pacific and rises in the Western Pacific, which has the tendency to leave coral in the East exposed above sea level at low tide or closer to the surface than is tolerable. The recent giant El Nino of 2015/16 was the culprit in the bleaching of the Great Barrier Reef, and El Nino’s are recurring natural weather events, not a result of AGW.
My god man! What planet are you from? Expecting the media to be honest! Here on planet Enzed where all those in higher authority, including TV Executives, are to bowed and scrapped to, the MSM is the font of all knowledge as they know best. (sarc. off).
In the meantime TVNZ continue to promote this garbage as it allies with the promotion of one of their big ticket items the second series, by that well known anti-humanist David Attenborough, about our planet. I didn’t stick around to watch a pre-recorded interview on TV 1 this morning with the producer & presenter of that documentary series (having eaten breakfast I wanted to retain it), but I would hazard a guess that somewhere in there were the usual rants about how we are killing the planet, and it is all our fault!
Expect much more of this nonsense before Bonn is over.
It is scary reading that latest GWPF Newsletter and seeing how strident the German Greens are and comparing the new found confidence the NZ version has now that they are finally in power. I have been weary of the Green Party in NZ for over a decade. I say this as a former member of the Values Party, which I joined at the ripe old age of 18, just in time for my first election and THE 1st election for 18 year olds! Rob Muldoon taught me a salutary lesson that day (1975.11.22) 42 years ago! I hung with the Values Party until the next election, but by that time although living in the city I had moved into one of those ‘clever’ areas that National made a part of a ‘safe’ rural seat with a cabinet minister ensconced, negating totally not only my protest vote, but my entire vote. Those who wonder why we have MMP now, would not have it any other way confronted with the same situation.
In the mean time when the influence of the 3rd party finally kicks in, in it’s own good time, I can only hope that some of the enthusiasm of the green zealots is brought into line with the thinking of those of us who enabled their participation in this Govt. in the first place. I, and many like me could just as easily vote blue next time if the ‘Green’ side of the equation gets out of hand as it is in Germany!
…”I have been weary of the Green Party in New Zealand for over a decade.” Weary or wary, both verbs are appropriate.
Opps, I just realised my original comment had East & West mixed up. It should’ve read as follows:
During an El Nino the sea level falls in the WESTERN Pacific and rises in the EASTERN Pacific, which has the tendency to leave coral in the WEST exposed above sea level at low tide or closer to the surface than is tolerable. The recent giant El Nino of 2015/16 was the culprit in the bleaching of the Great Barrier Reef, and El Nino’s are recurring natural weather events, not a result of AGW.
Writing comments just before bed is not such a good idea.
I’m glad you picked up your unintended error, Magoo. However, you left part of the reason for coral bleaching out of your comment. Not only did the pressure conditions of El Niño leave some areas of coral uncovered, it exposed more coral than is usual with tidal movement, and left some coral exposed for a longer time than usual. This latter caused more coral bleaching than usual. As John pointed out, there has been a substantial recovery since the peak of the El Niño, so the process appears to be reversible—or regrowth is possible, perhaps probable.
I can contrast the GBR with two areas of the coral reefs of the Dampier Archipelago on the Western side of Australia. Part of that reef is shallow and is exposed for long periods at low tides—the tidal movement in the northern parts of Western Australia is large. In the mid 1970’s I walked over that reef at low tide on several occasions. Some of the corals were bleached but some species survived the long exposure times. The worst problem, I thought at the time, was actually the fine silt which covered that part of the reef but perhaps the silt helped the coral survive.
On the south-western side of the Dampier Peninsula the coral reef at that time was covered with water most of the time and offshore looked to me to be pristine judging by the reefs close to the surface which were alarmingly (to me!) close to the bottom of boat I was fishing from.
I don’t know how the processing of natural gas on the Dampier Peninsula has affected the reef since then. The facilities were built long after we departed the region.
There is no doubt that coral bleaching can be caused by elevated sea surface temperatures. The 2016 temperatures recorded at Townsville were high by recent standards, but similar levels were reached no less than four times during the 1930s (Jones 1995).
Bleaching occurs in only in mid-summer. David Middleton has graphed GBR temperatures over summer months and finds that 2016 was only the sixth highest this century – i.e. about average. In fact, the most complete on-reef weather station (Agincourt #3) shows there has been no warming trend in GBR temps since 1991.
https://wattsupwiththat.com/2017/10/02/great-barrier-reef-2016-coral-cover-loss-and-local-sea-level-fall
So what caused the 2015-16 bleaching? As Magoo and Gary point out (above) the effects are closely correlated with a sharp drop of about 200mm in sea levels throughout the GBR region, caused by the giant El Nino. Middleton cites authorities noting that coral reefs react very poorly to any sharp reduction in their seawater cover.
https://wattsupwiththat.com/tag/great-barrier-reef/