Ok for Nemo, No Good for Bundie

I was on ABC Television’s 7.30 Report last night suggesting we move beyond the argument of whether or not rising atmospheric carbon dioxide levels are contributing to global warming and prepare for climate change anyway.

The program was focused on the release of a report titled ‘Climate change risk and vulnerability – promoting an efficient adaptation response in Australia’

Federal Environment Minister Ian Campbell was on the same program suggesting that global warming is going to destroy the Great Barrier Reef.

The reality is that global warming is OK for Nemo, but no good for Bundie. (Bundie is the name of the polar bear on the Bundaberg Rum advertisements?)

As my friend and colleague Dr Peter Ridd wrote last November at OLO:

If the climate is warming due to greenhouse gas emissions, there could be many plausible consequences, such as melting ice and polar bears not having a home. However, of all the ecosystems in the world, coral reefs are in virtually the best position to come through unscathed. They are certainly not the worlds canary as has sometimes been stated.

Consider the following points

(1) Corals are a tropical species. They like warm water. Most of the species found on the Great Barrier Reef (GBR), for example, are also found in areas with much warmer water.

(2) In a couple of hundred million years of existence, corals have survived through hotter, (and more seriously colder) periods.

(3) Coral tissue thickness, often seen as an indicator of coral health, is generally higher for corals in hotter water. Some of the highest tissue thickness’ measured have occur around PNG where the water is far hotter than the GBR.

(4) For all the hype about the bleaching events on the GBR, most of the reef did not bleach and almost all that did bleach has almost fully recovered.

(5) From the statistical viewpoint it is highly improbable that bleaching only started to occur in the last 25 years. Bleaching on the GBR occurs in summers when there is a combination of low cloud cover and light winds. This drives up water temperatures to a degree or two about normal. The water temperature has not increased by a degree over the last 25 years and thus bleaching must have been occurring previously, though quite possibly at a reduced rate. The apparent increase in bleaching is quite possibly due to the very large number of scientists and managers who are now interested in the phenomenon.

(6) Data of coral growth rates from massive corals indicate that there has been a small but significant increase over the last 100 or so years. This is related to the small but significant temperature increase that has occurred in the last hundred or so years. This is not surprising, coral, by and large like hot water.

(7) Some corals clearly are killed by unusually elevated temperature. These are not the long-lived massive corals but rather the plate and staghorn corals. These susceptible corals have the living philosophy of a weed, i.e. live fast and die young. The massives are in for the long haul, they are like the forest giants that live for hundreds or years and must thus be able to withstand the extreme conditions, such as high temperature and cyclones, that will temporarily wipe out there frail but fast growing brethren.

(8) Even the susceptible corals seem to be able to adapt to higher temperatures by replacing the symbiotic plants (zooxanthellae) that are embedded within them with more suitable species.

(9) If we see a sealevel rise due to the thermal expansion of the ocean, we will see a great expansion in the area of the GBR under coral. This is because the reef flats, which now have almost no coral due to the FALL in sealevel of the last 5000 years, will be covered even by the lowest spring tides. The presently dead reef flats, which are a very large proportion of the reef (perhaps the majority), will come alive. So though rising sealevel might be bad if you live in a small South Pacific Island nation, it will be good for coral.

I have a very high regard for the hardiness of corals. The GBR was borne at a time of rapidly rising sealevel, very high turbidity and very rapidly rising temperature. Presently, they live in areas of extreme temperature (40 degree), in muddy embayments and in regions continuously affected by runoff. Provided they are not grossly overfished, as has happened in the Caribbean, they are very adaptable systems.

My message is that if you must make an argument for the Kyoto Protocol, then using coral reefs is a poor, and implausible choice. In the final analysis, corals like hot water, polar bears do not. Corals will do badly in an ice age, polar bears and alpine meadows can suffer in a warm period.

Some links:

The Report ‘Climate Change: Risk and Vulnerability: Promoting an Efficient Adaptation Response in Australia’ http://www.greenhouse.gov.au/impacts/publications/risk-vulnerability.html

Summary of ABC Television’s 7.30 report
http://www.abc.net.au/7.30/content/2005/s1423001.htm.
The detail of the Minster’s comments on the Great Barrier Reef are not in the summary transcript.