Effective local management actions can enhance reef resilience in the face of climate change
Project Leader: Dr Scott Wooldridge, AIMS
This MTSRF-funded work has provided quantitative insight into many of the management response problems (e.g., ‘what type?’, ‘how much?’, ‘where?’, and ‘by when?’) that presently face coral reef managers tasked with maintaining reef resilience in the face of climate change. The benefit of 20%, 40%, 60% and 80% reductions in end-of-river dissolved inorganic nitrogen (DIN) concentrations in raising the thermal tolerance (i.e. bleaching ‘resistance’) of inner-to-mid-shelf reef sites on the Great Barrier Reef was modelled alongside two alternative global CO2 emission scenarios: (a) No mitigation (‘business-as-usual’), and (ii) CO2 mitigation leading to atmospheric stabilisation of CO2 concentrations at 450 ppm early in the 22nd century. The ‘ReefClim’ software package was used to develop regional-scale sea surface temperature (SST) patterns for the Great Barrier Reef until 2100. The dominant feature of the projected SST warming from all climate models tested was a proportionately higher rate of warming in the central-southern Great Barrier Reef. Simulated reductions in end-of river DIN loads appear to offer considerable improvements in the future survival prospects of locally-impacted reefs. The model projections demonstrated that in the area between Cardwell and Bowling Green Bay, an 80% reduction in DIN permits the maintenance of the coraldominated reef state for an additional ~50 years beyond current projections for the ‘business-as-usual’ (no mitigation) warming scenario. Moreover, when coupled with the CO2 mitigation (‘stabilisation at 450 ppm’) warming scenario, the enforcement of ~50% reduction in DIN is suffi cient to ensure the long-term persistence of the impacted reefs.
Extrapolation of the modelling framework across the entire flood-impacted Great Barrier Reef domain enabled a projection of the likely timeframe (yr) for the loss of viable reef communities given the No mitigation and CO2 Mitigation warming scenarios. Results show that:
- In the absence of any DIN reduction, the viability of a large proportion of inshore reef area is already marginal (in 2010), owing to the fact that the present day (2010) disturbance frequency experienced by many inshore reef communities is already likely to exceed their long-term capacity to maintain reef-building capacity; and
- Local reductions in DIN loads of ~50% and global atmospheric CO2 stabilisation below 450 ppm are needed to ensure the long-term persistence of impacted reefs.
The outcomes of this work demonstrate that both local and global strategies are needed to prevent the imminent mortality risk and loss of resilience that currently characterises the inner-to-mid-shelf reefs of the Great Barrier Reef.
How will reef degradation affect the tourism industry?
Project Leader: Dr Scott Wooldridge, AIMS
To help quantify the impacts of future degradation in the health of the Reef on Queensland’s lucrative marine tourism industry, MTSRF-funded researchers have developed a prototype model that quantifies the relationships between tourist perceptions, reef condition and economic and enjoyment valuation of reef trips. The model shows clear relationships between changes in reef condition and tourist visitation, financial valuation and satisfaction of reef trips. Reefs in excellent condition have the capacity to achieve twice the income as degraded reefs (i.e. reef states that are likely under unmitigated climate change), however variability is large. At this stage it is unclear from the data whether the drivers of this change result directly from changes in tourist demand for higher quality reefs, or from operators’ decisions about which reefs they will visit, and thus requires more investigation. While tourists are able to rate reef aesthetics quite accurately, they are less skilled at rating reef quality, implying that tourists may recognise the effects of climate change as aesthetic but not as ecological losses. Climate change impacts on the tourist industry are likely to happen through their enjoyment of the reef experience rather than their valuing the loss of ecosystem services. For example, the model shows that tourists visiting top condition reefs during bad weather are more likely to perceive the reef to be of poorer quality than those visiting top condition reefs in good weather. If climate change also brings more good weather periods, then the impact of climate change on tourist satisfaction may be diminished, and vice versa. These results from the prototype model imply that while the tourism industry has some capacity to overcome potential financial losses due to reef degradation, this capacity is limited; however, it has the capacity to realize greater financial benefits from high quality reefs. These results were produced using ecological and visitation statistics for four reefs, and trends may change as more reefs are added.
Report Series No. 32 - Miles, R. L., Kinnear, S., Marshal, C., O'Dea, G. and Greer, L. (2009) Assessing the socio-economic implications of climate change (coral bleaching) in the Great Barrier Reef catchment: Synthesis Report
A project update detailing work to simulate the beneficial impact of end-of-catchment dissolved inorganic nitrogen (DIN) reductions (10%, 30%, 50% and 70%) in raising the bleaching resistance of inshore coral reefs between Townsville and Cooktown, North Queensland.
Project 2.5i.4 AIMS Wooldridge, S. (2009) Modelling the improved resilience of inshore coral reefs to climate change due to terrestrial water quality improvement: A case study from the Burdekin River catchment
Submitted as a component of Project 2.5i.4 January 2009 milestone report.
A case study from the Tully-Murray River catchment, North Queensland. This report outlines research to model the 'envelope' of future bleaching risks to inshore coral reefs of the Great Barrier Reef that are under the influence of the Tully-Murray flood plume, based on a range of optimised land management actions.
A project milestone report describing the downscaling methodology developed to enable GCM-scale scenarios of future SST to be interpreted as a regional-scale coral bleaching threat on the Great Barrier Reef Australia.
A project progress report outlining modelling methodology that enables end-of-river values of DIN to be spatially extrapolated across the inner-shelf region of the Great Barrier Reef lagoon. Importantly this allows the end-of-river outcomes of modelled land-use improvement scenarios to be tested for their relevance in terms of improving inshore reef water quality.
A project progress report outlining the metadata of the inshore Great Barrier Reef datasets.