Question 2.2 What are the current and predicted impacts of climate change on Great Barrier Reef ecosystems (including spatial and temporal distribution of impacts)?

Studies over the last three decades confirm that the climate of the Great Barrier Reef is changing rapidly and in multiple ways, with some changes already significantly impacting Great Barrier Reef ecosystems and selected organisms. These studies also clearly show that impacts are predicted to intensify rapidly throughout this century, with severity depending on CO2 emissions pathways. Climate change is now widely accepted as the most significant threat to the long-term outlook of Great Barrier Reef coral reef ecosystems. The main climate change agents known to affect coastal and marine ecosystems include warming temperatures, increasing frequencies of marine heatwaves, increasing ocean acidification, extreme rainfall events, changes to the frequency and intensity of droughts and drought-breaking floods, sea level rise, and a potential reduction in the frequency but increasing intensity of tropical cyclones. Of great concern is the prediction that conditions that lead to heat-induced coral bleaching will become almost annual by 2040, depleting sensitive species and severely threatening the ecosystem integrity of coral reefs. By 2030, the evidence consistently indicates that some reefs will already start experiencing a seawater carbonate saturation state below ecologically critical levels, diminishing reef accretion and reef recovery rates. The strong link between rainfall extremes and terrestrial runoff of pollutants into the Great Barrier Reef show that climate change is already impacting Great Barrier Reef water quality, and these impacts will continue to intensify. The evidence also demonstrates the cumulative impacts from climate change and water quality, with the latter adversely affecting recovery times and community composition as climate disturbances are becoming more frequent and intense. The evidence confirms the urgency of meeting all Great Barrier Reef ecologically relevant water quality targets within the next decade before climate impacts exceed the capacity for reef ecosystems to persist.

N/A

N/A

N/A

N/A

N/A

N/A

98