read the comments from the Australian. http://blogs.theaustralian.news.com.au/letters/index.php/theaustralian/comments/barrier_reef_is_indeed_threatened_by_warmer_globe/

Jennifer Marossey is spreading lies again.

Jennifer/Pollyanna's just doing what she's paid to do. There's probably some people who believe her spin, but they don't include people who actually have expertise in this area - like the director of the ARC Centre of Excellence for Coral Reef Studies in his succinct rebuttal of her specious claims (link above).

for grahamY

"Tim. it's not "abuse" to suggest you are being fundamentally dishonest, just a dispassionate assessment from the editor of this journal. If you weren't included in the BB06 collection you wouldn't have got a guernsey for publication in OLO for this essay."

i guess the same standards of intelectual honesty dont apply to positions you agree with?

techinicaly of course most of the information in this article is correct, however it is the ommission of contrary evidence (which would lead to a very different conclusion) that marks this article as dishonest.

Unfortunately the article referred to above by Terry Hughes is neither a refutation nor rebuttal of any points made by Jennifer Marohasy. It simply asserts that she is wrong and in the end resorts to his "authority" as to why he should be believed. I am not saying Jennifer Marohasy is right or wrong but Terry Hughes has not provided any evidence that she is wrong on any point.

What global warming?

Rockhampton is shown as a hot spot of warming in Queensland. But a closer look found that the BOM data from Rockhampton PO from 1871- 1939, when compared to the data from the new station at Rockhampton Aero (5km away) shows mean annual temperature has actually declined by 0.40 degrees over the past 63 years.

The mean maximum has gone down by 0.2 degrees from 28.5 to 28.3 degrees while the mean minimum has gone down from 17.2 to 16.6 degrees.

The DNRM data on the frequency of extreme temperature events (1939-2003) tell us the number of days with maximum greater than 35 degrees has only increased from 15 to 19 days a year, in a range of zero to 45, while the number of days with minimum less than 5 degrees has dropped from 16 to 6 days a year, in a range from zero to 35 days.

This "hot spot" of temperature increase is only present over the interval from 1910 to 2003 as mapped by the BOM so the actual observed decline from the 1871-1939 data set must be from very high readings prior to 1910.

And this means;

Rockhampton, has actually cooled by 0.4 degrees over the past 64 years,
Rockhampton's climate is getting milder with fewer extremes,
The region can warm by 0.4 degrees before it exceeds the mean from 1871 to 1939,
If the region does get warmer it will be due to a reduction in cold weather, not an increase in warm weather, and
A reduction in cold minima poses no threat of increased bleaching.

Remember, Rockhampton was chosen as a representative, worst case site, by Qld DNRM, not me.

Furthermore, The length of coastal rainfall events has declined from 3.5 days to 3.2 days while the intensity has increased from 5mm to 6mm per rain day. So each rainfall event will deliver an improved mixing of surface waters and thereby disrupt the warm surface layers that build up in calm conditions and which cause most bleaching.

See www.bom.gov.au/climate/averages/tables/cw_039083.shtml And "Climate Change, The challenge for natural resource management" at www.nrm.qld.gov.au

Perseus

Please don't quote real facts when it comes to global warming. You spoil everyones fun.

Marohasy is correct to suggest that moderate global warming may well be good for the GBR, or at least not a significant threat. Although many scientists such as my colleague Terry Hughes (that CJ Morgan mentions) believes that the GBR is seriously threatened, there are others of us who look at the evidence and come to a different conclusion. The science indicates the following.
• The warming that has already occurred over the last 100 years has increased the rate of growth of massive corals.
• The species we have on the GBR are also found in much warmer water in PNG.
• Growth rates of corals increase linearly with temperature up to temperatures significantly higher than those that the GBR experiences.
• The only corals on the QLD coast that are temperature stressed are those of Moreton Bay and that is because they are in an environment that gets too cold in winter. They will certainly benefit from global warming.
• In the recent bleaching events, most of the GBR did not bleach and almost all that did bleach has almost completely recovered.
• Recent research here at JCU also indicates that corals are able to take on different strains of Zooxanthellae after bleaching events and these "low octane" strains make them grow more slowly but protect against future bleaching.

Although in my view moderate increases in temperature are good for the GBR there is reason to worry about the effect of changes in pH on coral growth. It will be interesting to see what science will eventually say about this.

On other issues, the reef is also only mildy affected by runoff or fishing. It is a huge rapidly flushed system and most of it is 100 km from the coast. The population adjacent to its 2000km length is only 0.5 million compared with many hundred times that number for the similarly sized Caribbean. The northern most 800 km has a few hundred people living close to it. There are many more threatened ecosystems to worry about than the GBR.

Peter Ridd, Physics, James Cook University

That's 'Jennifer Marohasy', billissey.

The ocean acidification scare is bunk for some very sound reasons.

1 It is dependent on, at least, a doubling of atmospheric CO2 which not even the barking mad have suggested will occur within 30 years as claimed by the ACF.
2 Even a doubling by 2100 is dependent on no substitution of nuclear for coal etc, and assumes that India, Africa and China will not only achieve fully developed status by 2100, but do so under the USA development model rather than the Japanese model that produces much less CO2.
3 The doubling of atmospheric CO2 is dependent on a slow rate of absorption of CO2 by the oceans which is supposed to cause the build up in the atmosphere but for acidity to get within cooee of harming the GBR in 30 years the ocean absorption would need to be faster than the projected emission rate.
4 The modelling done by the UK Royal Society on ocean acidity assumed that the mixing of CO2 in sea water only took place in the top 100 metres. The average ocean depth is actually 4000 metres so the CO2 was assumed to be concentrated in the top 2.5% of ocean volume.
5 This ignored the fact that eddies from the Gulf Stream reach depths of 1.2km and also ignored the presence of thermohaline circulation of deep ocean water. They also pretended that deep ocean upwelling, like the one that produces EL Ninos, don't exist.

The general view is that complete ocean circulation needs about 400 years to complete. So a modelled projection of ocean CO2 absorption over 100 years must assume that CO2 will be absorbed by 25% of the entire ocean volume.

The UKRS used only 2.5% of ocean volume or a tenth of the correct volume to claim a concentration of acidifying CO2 that is 10 times stronger than the correct result.

The "acid ocean" threat to the reef is as weak as water.

Re the global warming aspects of this topic, authoritative groups of scientists and economists have just released critiques of the science and economics of the Stern Review. In summary, they conclude that the Review fails to present an accurate picture of scientific understanding of climate change issues, and will reinforce ill-informed alarm about climate change. Two interrelated features of the Stern Review are that it greatly understates the extent of uncertainty as to possible developments, in highly complex systems that are not well understood, over a period of two centuries or more; and its treatment of sources and evidence is persistently selective and biased. These twin features have combined to make the Review a vehicle for speculative alarmism. In the judgement of the authors of the Dual Critique, the Stern Review mishandles data; gives too little attention to actual observation and evidence, as distinct from the results of model-based exercises; and takes no account of the failures of due disclosure, and the chronic limitations of peer reviewing, that have been characteristic of work relating to climate change which governments have commissioned and drawn on. As to specifically economic aspects, the authors note among other weaknesses that the Review systematically overstates projected costs of climate change, partly though by no means wholly as a result of its failure to acknowledge the scope for long-term adaptation to possible global warming; underestimates the likely cost—including to the world’s poor—of the drastic global mitigation programme that it calls for; and proposes worldwide adoption of a specially low rate of interest for discounting the costs and benefits of mitigation, on the basis of inadequate analysis and without regard for the problems and risks that would result. So far from being an authoritative guide to the economics of climate change, the Stern Review is deeply flawed. It does not provide a basis for informed and responsible policies. (www.world-economics-forum.com)

So let’s not get over-excited at this stage. The above is the abstract for the paper – I also have some points from it.

I agree that coral reefs will generally benefit from warmer conditions….if you define ‘benefit’ as bigger, more robust and more rapidly growing.

But how will climate change / temperature increase really affect the ecosystems on the reef?

Higher temperatures will favour vigorous species and disadvantage species adapted to marginal conditions. Thus, the species balance will change with less competitive species being disadvantaged and perhaps eliminated from large areas, or perhaps even rendered extinct.

Our knowledge of the intricacies of ecology on the Great Barrier Reef is not good enough to know just what the impacts of climate change might be for some species. But if it is anything like terrestrial ecosystem mosaics (and basically it is), then increasing temperature is not going to have an overall positive effect, it is simply going to lead to a change in the balance, which will favour some species and threaten others.

Climate change very likely presents the illusion of increased health and vigour on the GRB while promulgating grave struggles for some species and a greatly increased level of ecological turmoil.

Aaaargh GRB my foot. That should be GBR of course.

I think Dr Peter Ridd presents a pretty realistic overview of the effects of climate change, and of runoff and other land-based activities on the GBR.

But given that these impacts are slight, it is very hard to imagine that climate-change-induced pH change could be a significant factor, especially in such as “rapidly flushed system” in the open ocean where any pH changes on the reef would surely be diluted into insignificance.

Those who are tempted to fall back on the old "sediment threat to the reef" chestnut can avoid ruining another pair of undies by reflecting on the fact that the reef has recently been a major beneficiary of anthropogenic change.

The new Dam on the Burdekin now traps just about all the silt in runoff from its vast catchment so there can be no doubt that the most populated part of the reef is now under substantially reduced pressure from both excess fresh water (which kills coral) and sedimentation.

And if anyone thinks this is not enough then all they have to do is support the construction of the Tully-Millstream Dam to do the same job further north.

To avoiding repeating myself:

http://forum.onlineopinion.com.au/thread.asp?article=5382#69529

:)

True Perseus, but is the virtual absence of a sediment plume and the reduction of the freshwater influence really good for the reef, or does it just change the species competition dynamics to the detriment of some species, as I mentioned in my last post?

Could it be that a new balance has been reached since the building of the Burdekin Dam and the capture of the enormous sediment loads due to overgrazing in the catchment? Could the impact on the reef from the current flood event be much greater than it would otherwise have been due to this new balance?

The reef has endured many storm events with their freshwater and sediment impacts over thousands of years, as is evident in the coral core record. It has also endured a greatly increased sediment load and then an instant virtual cessation of that impact, at least in the region off Townsville. And it has endured fishing pressure, bleaching events and so on, without any real consequences….as far as we know.

So while climate change and other anthropogenic factors will impact on it, and the species balance will change, I can’t see that the overall effect would be all that significant.

Now, this leads me to be in agreement with two people with whom I have found massive disagreement on this forum – Jennifer and ol’ Perseus the soiled underwear expert.

Yahoo! Wonders will never cease!!

Wonders never cease, Ludwig. But you do seem to be arguing that coral could have adapted to less fresh water since the Burdekin Dam but fresh water is the worst killer of coral. I also notice that all the bleaching events are close to the coast with next to nil bleaching in the outer reef. And this, given that there is still a lot of bleaching near the Burdekin Delta makes me suspect that the increased volume of urban storm water runoff is the culprit.

Urban development, without water tanks, currently turns half of each hectare of land into a 100% efficiency catchment. And in places like Airlie Beach, that means an extra 15 megalitres of coral poison for every ten new houses. Coastal urbanisation is the only change that has produced volumes sufficient to change inshore water salinity on the scale observed.

For all the rapid coastal development along the central and north Queensland coast, I can hardly imagine that stormwater runoff would be significantly greater in terms of impact on the reef, or even on inshore reefs.

I guess the key reefs to look at in Australia in terms of increased stormwater runoff effect would be the fringing reefs around Magnetic Island, just off Townsville which has grown enormously in recent times. I don’t know how they have changed over this period. Perhaps Peter Ridd can help us out here.

We need an expert to inform us of the causes of coral bleaching in various spots around the world, so that we can get a wider perspective of the possible effects of freshwater. The cause seems pretty categorically to be temperature-related.

Anyway, expanding the subject to the big picture: the effects of climate change are going to be mixed, and possibly even insignificant. All I can say is that we had better be prepared for a scenario that is towards the bad end of the spectrum, and that means getting stuck into preparations now.

Climate change is tooo big to handle! So rather than concentrating directly on dealing with it in Australia, we should be concentrating on the absolutely vital task of achieving sustainability. And in so doing, we would reduce greenhouse gas emissions more effectively than if we try to do it outside of a sustainability paradigm, ie with the continuous growth mentality still entrenched.

There is a need here to address some specific points that have been made in the original article and subsequent posts,

Article said - It will extend its range further south and this would be a good thing.
Firstly, there is minimal shallow water area along the East Australian coast south of the GBR, and most of it is siliceous sand.

Even if 'it' did 'move south', what would be left behind would probably be of different composition and ecosystem function. Same goes for the 'new' GBR to the south - is that a good thing? It is at a far greater level of complexity than a presence/absence issue.

Article said - Sea level rise will benefit corals
Sea level rise too gradual to be an issue in the context of benefiting the GBR before other climate change impacts.

Article said - Corals resistant to climate change and have/can adapt.
The issue here is that the rate and magnitude of this recent change is quicker than corals have had to deal with in the past

Ridd said "warming has increased the rate of growth of massive corals"
Firstly, this comes at the expense of coral skeleton density. Reduced skeletal density makes them much more prone to cyclones and storms. For long-lived, relatively slow growing massive corals, this has particular importance at the population level. Secondly, that pattern is not universal across all species.

"Moderate increases a good thing for the GBR"
It is not all about growth rates of adult colonies. Temperature affects many other properties, for eg., reproduction rates, larval dispersal and survival. This is a big topic, so I'll just touch on it. For example, for non-feeding coral larvae, increasing temperature may relate to quicker metabolism, quicker rates of development, therefore less potential to disperse far, therefore reduced connectivity among reefs and less potential to recover from disturbances.

What a joke, Vade Mecum. First you claim there is no shallow water south of the GBR and manage to overlook Moreton Bay, where the corals are strugling because of the cool weather. But then, according to you, there is no shallow water at Burleigh, Greenmount, Fingal, Kingscliff, Cabarita, Bogangar, Brunswick, Byron Bay, Broken & Lennox, Ballina, Coffs. Give us a break.

Then you claim the sea level rise will be too gradual to benefit corals. But in the very next para you claim the rate of change is too fast for the corals to adapt. Bollocks.

Perseus,
It should have been clear that I meant 'suitable' shallow water. Do you think a few little headlands dotted down the coast are significant enough to support a whole coral reef ecosystem, with the same ecological ‘goods and services’ that they currently do now? Some of those headlands are smaller than an average sized reef and remember there are about ~2,900 reefs in the GBR. Do you know if those headlands will support the same diversity of species and provide the same range of habitats? Will all coral species recruit to that granite and basalt etc surface? Will they be able to compete with and how will they alter the existing communities? Will those headlands support viable populations of corals? Will the corals that colonise those headlands support the diverse range of ‘interstitial’ species of fish, invertebrates etc that use corals as habitat? Suitable temperature regime is just one of many variables, and it is rather dilettantish to presume that temperature is the only factor that regulates the distribution of corals.

Sure a few coral colonies might be able colonise those headlands, but I doubt the headlands will be able to support anything that resembles the ecological functioning of the GBR. So I still struggle to see how “The GBR is likely to extend its range further south” and how that would “benefit coral reefs”.

By rate of climate change being too fast – I didn’t mean sea level. I meant the effects of more pertinent variables like temperature, CO2 etc. I wasn’t talking about corals adapting to sea level rise.

Also, I wouldn’t trust a physicist to tell you that the corals in Moreton Bay are ‘struggling’, do you have a reference I that I could read about that?

Posters may wish to log on to the Marine Conservation Biology Institute (US) to find their scientists claiming that:

1........The oceans are more acidic today then they have been in 650,000 years

2........ 1 million tonnes per hour of CO2 now enter the oceans - 10 times more than the natural rate

3........500 billion tonnes of CO2 absorbed by oceans since the Industrial Revolution

4........Acidity reduces the abundance of the right chemicals forms of a calcium carbonate to which corals and other sea animals need to build shells and skeletons

5........Acidified waters tend to asphyxiate animals that require a lot of oxygen

6........The lethal acidification of oceans, with the subsequent reduction in ph, will not be arrested until pollutant industries cease fouling the atmosphere with carbon dioxide

7........The change in modern surface ocean ph will be much more extreme that it was 55 million years ago.

8........Algae, bacteria etc are already proliferating at the expense of marine animals and corals.

Now, in my region, last month, 4,000 birds falling out of the sky in Esperance - dead! Autopsy found no evidence of viruses though poisoning by heavy metals was "inconclusive!"

This week another 1,000 or so dead birds in different areas around Kelleberin, Kukerin and Kulin.

I recall temperatures of 112 degrees fahrenheit when I was a kid though no evidence of birds dying from the heat then.

What say thee, Jennifer?

I omitted to advise Perseus that the MCBI also advise that cold waters absorb more CO2 than warm waters.

Since this thread is on the fate of our coral reefs, global warming is not as relevant as the excessive human induced emissions of CO2 which is polluting, acidifying and subsequently destroying marine life in our oceans.