Friday, November 7, 2008

Special Guest Contribution: Will we leave the Great Barrier Reef for our children? -- Dr. Chris McGrath

Dr Chris McGrath is an Australian lawyer and researcher on laws protecting the GBR from climate change. This article is based on a previously published research paper, McGrath (2008).  Submitted 30 October 2008.


Amidst the current policy debate in Australia and internationally on climate change is a surreal argument that policies that will destroy the Great Barrier Reef World Heritage Area (GBR) and other coral reefs around the globe are acceptable and economically rational.

Nicolas Stern (2007: 330) concluded that “coral reef ecosystems [will be] extensively and eventually irreversibly damaged” by temperature change relative to pre-industrial levels of 0.5-2°C. He found that at 2°C warming “coral reefs are expected to bleach annually in many areas, with most never recovering, affecting tens of millions of people that rely on coral reefs for their livelihood or food supply” (Stern 2007: 94).

Yet for what were clearly reasons of pragmatism and feasibility he recommended the global stabilisation goal should lie within the range of 450-550 parts per million carbon dioxide equivalents (ppm CO2-eq), thereby implicitly accepting a likely warming of 2-3°C and loss of coral reefs, including the GBR.

Ross Garnaut, the Australian Government’s handpicked economic advisor on responding to climate change, followed Stern’s approach and was alive to the damage to the GBR. He recommended that Australia should initially aim for a global consensus next year at COP-15 in Copenhagen to stabilise greenhouse gases in the atmosphere at 550 ppm CO2-eq and hope that global consensus can be reached later for lower stabilisation.

Garnaut (2008a: 38) was brutally frank in his supplementary draft report: “The 550 strategy would be expected to lead to the destruction of the Great Barrier Reef and other coral reefs.” His final report does not shy away from this conclusion (Garnaut 2008b). 

The new Australian Government has silently avoided the issue of the expected impacts to the GBR when explaining the costs and benefits of its climate policies. It does not yet have a stabilisation target for the rise in global temperatures or greenhouse gases but recent modelling of economic impacts of mitigating climate change considered only three stabilisation targets.

The Australian Treasury (2008) considers only stabilisation at 450, 510 and 550 ppm CO2-eq, aiming to stabilise mean global temperature rises between 2-3°C. The only reference to impacts on the GBR is to a “very high risk [of] loss of complete ecosystems, such as the Great Barrier Reef [if] the concentration of greenhouse gases in the atmosphere rises to over 1,500 ppm CO2-eq by 2100 [giving an] increase in global average temperature of 5°C above pre-industrial levels by 2100” (Australian Treasury 2008: 35).

In fact, as Stern recognised, the current science indicates that the GBR will be devastated long before such levels are reached and within the lower stabilisation range the Australian Government appears to be aiming for.

Stern and Garnaut’s frank admissions of the expected impacts to the GBR reflect research findings since mass coral bleaching occurred globally in 1998 and 2002. Rising sea temperatures and increasing acidity of the oceans due to our use of fossil fuels are now well-recognized as major threats to coral reefs and the marine ecosystem generally in coming decades.   

In relation to coral bleaching the IPCC (2007b: 12) found that:

“Corals are vulnerable to thermal stress and have low adaptive capacity. Increases in sea surface temperature of about 1 to 3°C are projected to result in more frequent coral bleaching events and widespread mortality, unless there is thermal adaptation or acclimatisation by corals.”

The findings of the IPCC suggest that a rise of 1°C in mean global temperatures and, correspondingly, sea surface temperatures above pre-industrial levels is the maximum that should be aimed for if the global community wishes to protect coral reefs. The range of 1-3°C is the danger zone and 2°C is not safe. Supporting this conclusion Ove Hoegh-Guldberg and his colleagues concluded in a review of the likely impacts of climate change to the GBR edited by Johnson and Marshall (2007: 295):

“Successive studies of the potential impacts of thermal stress on coral reefs have supported the notion that coral dominated reefs are likely to largely disappear with a 2°C rise in sea temperature over the next 100 years. This, coupled with the additional vulnerability of coral reefs to high levels of acidification once the atmosphere reaches 500 parts per million [CO2], suggests that coral dominated reefs will be rare or non-existent in the near future.”

The IPCC’s (2007a: 826) best estimate of climate sensitivity found that stabilising greenhouse gases and aerosols at 350 ppm CO2-eq would be expected to lead to a rise in mean global temperatures of 1°C, stabilising at 450 ppm CO2-eq will lead to a rise of 2°C, and stabilising at 550 ppm CO2-eq will lead to a rise of 3°C.

Atmospheric concentrations of greenhouse gases and aerosols have already passed 350 ppm CO2-eq making stabilisation at that level extremely difficult if not impossible in practice, particularly in the context of current global growth and energy use patterns. Atmospheric CO2 reached 379 ppm in 2005 and was increasing by around 2 ppm per year (IPCC 2007c: 102). Including the effect of other greenhouse gases such as methane, the total concentration of atmospheric greenhouse gases was around 455 ppm CO2-eq in 2005 (IPCC 2007c: 102). However, the cooling effects of aerosols and landuse changes reduce radiative forcing so that the net forcing of human activities was about 375 ppm CO2‑eq for 2005 (IPCC 2007c: 102).

Global emissions of carbon dioxide, the major anthropogenic greenhouse gas, are growing at approximately 3% per annum, which exceeds even the “worst case” IPCC projections (Raupach et al 2007). This places global greenhouse gas emissions on a trajectory to rise by 150% between 2000 and 2050 on “business as usual”.

When the conclusions of the IPCC are synthesised, it is clear that reductions of greenhouse emissions of 60% by 2050, such as proposed by the Australian Government (2008), even if they can be achieved, are not likely to prevent serious damage to the GBR and other coral reefs. A 60% reduction in global emissions by 2050 is likely to lead to a mean global temperature rise around 2.4°C (IPCC 2007d: 67), which is likely to severely degrade coral reefs globally. Stabilising greenhouse gases and aerosols around 350 ppm CO2-eq and allowing a rise in mean global temperature of 1°C appear to be the highest targets that should be set if coral reefs are to be protected from serious degradation.

This brings us back to the current policy debate – Stern and Garnaut’s frankness in recognizing the likely damage to the GBR and coral reefs from the targets they recommend is welcome but their conclusions leave us to wonder: is this the best we can do? Should we be prepared to write-off the GBR and other coral reefs and their economic, social environmental values?

As a young boy growing up in Australia’s Whitsundays Islands in the 1970s I did not dream that the GBR that I swam and fished on would be severely damaged by human activity within my own lifetime. Much less would I have dreamt that we would choose to allow these impacts to occur, as we are currently doing.

Stern and Garnaut’s targets are not ambitious enough and we should not accept them.

We should judge our climate change policies by this simple test: will we leave the GBR and other coral reefs around the world for our children? At present the answer we are giving to this question is “no”. We are all responsible for changing the answer to “yes”.

We should demand targets based on what we as a society want to achieve. We should not accept targets that will produce unacceptable outcomes.

The current science indicates our aim should be stabilising atmospheric greenhouse gases at 350 ppm if we want to protect the GBR and other coral reefs, but this is rarely even mentioned as a potential target.

We do not yet know if we can stabilise atmospheric greenhouse gases as 350, 450 or 550 ppm CO2-eq but think of it this way: if we want to build a bridge across a river that is 1 kilometre wide we would not ask our engineers to build us a bridge that is 500 metres long. We should apply the same logic to climate change policy and set targets for our engineers and scientists to achieve that produce results that we want to achieve.

We need vision, ambition, and hard work to solve the climate crisis. Stern and Garnaut’s approaches lacks the vision and ambition that is needed. We need to add these ingredients to the global community’s many hard workers to solve the climate crisis.


Australian Government (2008), Carbon Pollution Reduction Scheme Green Paper (Department of Climate Change),

Australian Treasury (2008), Australia’s Low Pollution Future: The Economics of Climate Change Mitigation (Australian Government Treasury),

Garnaut R (2008a), Garnaut Review Supplementary Draft Report: Targets and trajectories (Garnaut Review, Canberra, 5 September 2008), p 38, available at

Garnaut R (2008b), Garnaut Climate Change Review Final Report (Cambridge University Press),

Hoegh-Guldberg et al, “Vulnerability of reef-building corals on the Great Barrier Reef to climate change”, Ch 10 in Johnson JE and Marshall PA (eds), Climate Change and the GBR: A Vulnerability Assessment (GBRMPA, 2007), p 295,

IPCC (2007a), Climate Change 2007: The Physical Science Basis. Contribution of WGI to the AR4 (Cambridge University Press),

IPCC (2007b), Climate Change 2007: Climate Change Impacts, Adaptation and Vulnerability. WGII Contribution to the IPCC AR4 (Cambridge University Press),

IPCC (2007c), Climate change 2007: Mitigation. Contribution of WGIII to the AR4 (Cambridge University Press),

IPCC (2007d), Climate Change 2007: Synthesis Report (IPCC),

McGrath C (2008) “Will we leave the Great Barrier Reef for our children?” (IUCN),

Raupach MR, Marland G, Ciais P, Le Quéré C, Canadell JG, Klepper G, and Field CB, (2007) “Global and regional drivers of accelerating CO2 emissions” 104(24) PNAS 10288-10293,

Stern N (2007), The Stern Review on the Economics of Climate Change (Cambridge University Press,

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