Swings and roundabouts on the Reef

The Great Barrier Reef is an international icon of great economic, social and environmental importance. When it comes to managing and protecting this resource a complex web of interactions is played out. Dr Peter Roebeling is using an economic approach to unravel the web.

In the Douglas Shire, it’s estimated that agriculture contributes 25% of the total 322,000 tonnes of sediment entering the Shire’s Great Barrier Reef lagoon each year. The remaining 75% comes from water originating from non-agricultural and World Heritage areas.

Peter says, “what is really needed to drive change in land management practices is information about how the economic values of the Reef change as the quality of the Reef changes.” In a case study for the Douglas Shire, Peter’s work starts to quantify the link between land based economic activities and marine based economic values, by asking questions such as, what are the marginal costs and benefits from water pollution, and what are the regional and global optimal levels of water quality in the Great Barrier Reef lagoon?

The method established the difference between regional and globally desired levels of water pollution mitigation, and enabled the assessment of a wide variety of controls and incentives that may lead to socially acceptable levels of water pollution mitigation.

Results in the Douglas Shire, the least developed of the Wet Tropics catchments, show that the current rates of agricultural sediment water pollution are close to the regional optimum if, and only if, we ignore: i) re-suspension of sediments, and ii) global non-use values of the Reef.

Results also indicate that if 25 percent of the sediments in the lagoon were re-suspended each year, then it would make sense (from an economic point of view) to reduce the rate of agricultural water pollution by about 30 percent. It is therefore likely that the current rates of agricultural water pollution are above the regional optimum.

Non market values of the Reef can also be significant. For example, visitors are willing to pay about $25 per trip extra to prevent the reef from degrading – nearly $4 million dollars for all reef visitors to the Douglas Shire. Therefore in the global context current rates of agricultural water pollution are far higher than the global optimal rate. Consequently, domestic and international compensation for external costs for conservation of the Reef resulting in reduced water pollution can play an important role in the protection of the Reef.

This is the type of information required for efficiencies in water pollution control as it ensures that policies and incentives reflect the true cost of mitigation for land based agricultural activities.

This is the first in a series of Flagship studies to quantify the link between land based economic activities and marine based economic values. Further study is required to: i) include the impact of nutrients on the reef and not just sediment; ii) take into account uncertainty in marine benefits from Reef conservation; and iii) determine changes in the rate of sediment re-suspension. We will need more detailed and quantitative estimates for these factors if we plan to develop and use incentives and policies to reduce pollution from agricultural sources.

This research is another important tool in the growing list of studies under the Flagship attempting to understand the complex dynamics of cane, cattle, the Reef, and the people who live and work in the region.

More information contact:
Dr Peter Roebling
Ph: +61 7 4753 8586
peter.roebling@csiro.au
 

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