|The coral reef crisis
J E N (Charlie) Veron
Ockham's Razor series, Australian Broadcasting
About a year and a half ago, I recorded an talk on this program called 'The Plea of the Great Barrier Reef', in which I laid out the case that Australia's greatest natural treasure is on the brink of wholesale destruction from the effects of climate change. I am happy to say that this plea was heard very widely; I am less happy that the dire predictions I made then, remain on track.
There are now two further books on this subject. In September, the Great Barrier Reef Marine Park Authority released their long-awaited Outlook Report, a government profile of The Reef which spells out just how the Authority sees the Reef's future, and just out is an excellent book for students called Coral Reefs and Climate Change, prepared and published by the University of Queensland. The bottom line for all three volumes is essentially the same: they show how and why the Great Barrier Reef is, indeed, in very serious trouble.
Among the many that heard my talk last year was an English zoologist who promptly came to my home in Townsville to discuss the lead-up to Copenhagen. 'It would be effective, Charlie', he said, 'if the Royal Society were to stage a full presentation of what you have to say, and have you introduced by David Attenborough, and have it spread around the world by Google'. Surprisingly, this all happened as he planned. A drop in the ocean perhaps, but it has helped highlight the plight of coral reefs. If you, listener, can spare an hour to hear me out, the URLs for this talk are on this program's website.
How well are Australians facing up to climate change? Do other countries give so much media coverage to so-called climate change sceptics? Do other countries politicise climate change issues like we do? The answers are 'no', and 'no'. The so-called anti-climate change lobby which has now transformed itself into an anti-climate-science lobby, seems to have no equivalent in other countries except, perhaps in the bible-belt of the United States.
There are real parallels between the anti-climate-change proponents in Australia and the anti-evolution lobby in the United States. Both claim that science is on their side yet both constantly make assertions that have no scientific basis whatsoever. Both are promoted by zealots who fancy themselves as crusaders acting for the greater good of God or country. Most significantly, both have proponents who call themselves scientists, but knowingly misrepresent science to support some story or other they want to put across. We all want to believe that human-induced climate change is not happening, but unfortunately the science is showing that it is. This science is overwhelming on every imaginable front.
All this reminds me of a time when I used to argue evolution issues with creationists. A complete waste of time, but harmless. However, when it comes to climate change, nothing less than the future of our planet is at stake., Seeing what has recently happened in Canberra, I feel that Australian scientists must give much more of their time and effort to raising awareness of real science for the general public, let alone parliamentarians. This is something most scientists hate doing, but if Australia does not lift its game, we will not play our part in avoiding the climate catastrophes that lie ahead. We are now the worst polluter per capita of any developed nation, and are on track to become the world's foremost exporter of pollution. Because of the Howard years, we are already lagging far behind. Among the G20 nations, a recent study ranked Australia 15th in preparedness for a clean energy future. Any comment I have about this will immediately be out of date, but in retrospect I believe we hit rock bottom with the popular Liberal Party view that Australia is too small to make a difference, so why not leave it to the big guys. That same argument would have been equally applicable to Australia's participation in both World Wars: should we have opted out of those also?
Dozens of major international conferences have now been held in the lead-up to Copenhagen. The overwhelming focus of these is on the science of climate change, on economic impacts, and on political issues. What is missing in all this? The plight of natural ecosystems. European climate change research organisations habitually forget this, as I have repeatedly discovered when giving seminars. With corals we are not just making predictions. The impacts have been happening for decades and are well recorded. This puts them in a class of their own.
The bottom line is this. We can argue computer predictions, economics and politics all we like, but we must never forget that we are ultimately dependent on the health of our planet's ecosystems, for our own existence.
Coral reefs are the natural ecosystems at the forefront of climate change. This is not only because of the recent track record they have left, but because corals are the Earth's natural ancient historians. Being carbonate platforms, reefs are very sensitive to ocean chemistry changes. This means that they respond quickly to disturbances in the carbon cycle, the sorts of disturbances which are at the root cause of extinctions. The mechanisms involved are not complicated. The carbon cycle is the greater matter cycle that links the biosphere to the geosphere. All life forms are part of it; so are rocks. Carbon dioxide is the fast-acting currency of the carbon cycle and it is carbon dioxide that is acidifying our oceans. This process alone seems capable of plunging our planet into a mass extinction.
When it comes to climate change, corals have two separate adversaries: global warming and ocean acidification. These are largely independent.
Coral reefs have been tracking global warming via the process of mass bleaching for 30 years. Bleaching occurs when the food-providing algae in the coral's tissues start producing lethal levels of oxygen in response to elevated temperature. Mass bleaching started occurring world-wide when carbon dioxide levels reached about 320 parts per million. This was in the late 1970s. By the early 1980s, sporadic, highly destructive bleaching occurred in response to levels of about 325 parts per million. We see this only in the rear-vision mirror today. Carbon dioxide has now reached 387 parts per million. At this concentration, were it to be held constant, we can be almost certain that most reefs world-wide would slowly decline. Up till now, this decline is linked to El Nino cycles, natural weather events which take place very 4-7 years. In future, bleaching is set to decouple from these cycles and become annual events. The whole process is speeding up.
Ocean acidification, the other great adversary of corals, is caused by changes in the ocean chemistry in response to carbon dioxide, dissolving in surface water and forming carbonic acid. The chemistry is simple and has been understood for a long time. Carbonic acid is neutralised by ocean carbonate buffers. When this process is speeded up, there is a shift in the ratio of carbonate to bicarbonate ions which, in turn, reduces ocean alkalinity, or pH. The acidification process is now well established in the cold Southern Ocean where carbon dioxide is relatively soluble. It will move towards the equator over the next few decades. Just how this will affect reefs is not known in detail, but it may already be slowing the rate of coral growth. As growth slows, branching corals will develop a sort of coraline osteoporosis as skeletons become progressively weaker. They will then cease to provide the three dimensional habitat which most reef species depend upon. It's analogous to taking trees out of forests, the whole ecosystem ultimately collapses. Without its biodiversity, reefs will be overtaken by algae and bacterial slime. I have seen such instances in many parts of the world now. They are deeply depressing sights because they point to the future.
If humans do not successfully curb carbon dioxide emissions now, we will reach the level of 450 parts per million by 2030 or soon after. This is the limit most climate change brokers are going for at Copenhagen because of the general belief that a maximum of 450 will limit global warming to 2 degrees, the global temperature widely believed that humans can endure without global collapse of agriculture and completely catastrophic sea-level rise. But what about natural ecosystems? At that level, reefs will be in rapid, terminal decline world-wide. First from temperature-induced bleaching, then through ocean acidification. There will also be knock-on effects to all ecosystems associated with reefs. Reefs will cease to be large-scale nursery grounds for fish and will cease to have most of their current value to humanity.
By around mid century, our predicament will, at current rates of emissions, become much worse. Carbon dioxide will have reached 600 parts per million and climate change will be in full runaway mode. Reefs will have little in common with their counterparts today. They will be eroding geological structures. Extinctions will be very widespread, for about a quarter of our planet's entire marine biodiversity is linked to reefs.
Although mass bleaching is a reef phenomenon, the effects of ocean acidification will directly impact not only corals, but calcareous algae, most molluscs, many crustaceans, echinoderms and planktonic life. It will also directly affect other taxa that rely on carbonates for skeletal growth and for normal cellular function. This includes fish which are particularly vulnerable during early stages of their life-cycle and also krill, the lynch-pin of the Southern Ocean. Research on these issues is still in its infancy, but the enormity of the threat, nevertheless, is real. What I am describing is the start of a mass extinction the likes of which the Earth has not seen for tens of millions of years.
Are we seriously, really seriously, on the verge of plunging the Earth into a mass extinction event? We can't be sure, but the evidence pointing in that direction is frightening. What we are doing is driving our planet into uncharted waters which, at the very least, is putting the health and welfare of all life on it at extreme risk.
Efforts at emissions reductions have so far been very limited. Recent slowing in carbon dioxide emissions seems more an outcome of the global economic crisis than anything to do with emissions reductions. It is critical that this situation be reversed through rapid and dramatic cuts. Even so, the outlook is grim: cumulative carbon emissions to date have already committed atmospheric carbon dioxide to remaining above 330 parts per million for at least the next thousand years. Returning to a safe level will necessitate creating new mechanisms of extracting carbon dioxide from the atmosphere.
Now we are talking geoengineering, a name given to human attempts to artificially control our climate. Personally I believe it will come to this, no matter what the cost or the risks. The Royal Society's review of geoengineering, published a few months ago, more or less says that the only safe way to extract carbon dioxide from the air is to give the job to plants. There are a lot of options here. We need to adopt them all.
Even so, we may well have left it too late for the Great Barrier Reef. This incredible place is on Death Row and at this point I see no clear way for a reprieve. But perhaps we will not be too late for most other ecosystems. Not if we are prepared to act decisively. Now.
I believe children alive today will celebrate the foresight of today's leaders for heading off a global disaster or else curse us all for failing to face up to the greatest challenge in human history when we had the chance.