Impacts of Climate Change Stressors on the Great Barrier Reef

In a high CO₂ world, coral reefs face a perilous future due to the multitude of co-occurring climate stressors. Climate change is causing sea-level rise, thermal stress, ocean acidification, and an increase in the intensity of storms with associated physical, hydromechanical, and hydrochemical impacts (Albright et al. 2016a; Cheal et al. 2017; Hoegh-Guldberg et al. 2017; Hughes et al. 2017a, 2017b, 2018; Putnam et al. 2017; Tebaldi et al. 2021; NOAA https://tinyurl.com/53z66rdj). Moreover, the rate and magnitude of change of these stressors are well beyond what modern reefs have evolved to cope with over geological timeframes (Pandolfi et al. 2011). Climate-driven warming and marine heatwaves have caused significant coral bleaching and mortality and in some cases, collapse of reef structures and associated communities on the Great Barrier Reef (GBR) and elsewhere (Hughes et al. 2017, 2018). Heatwaves, especially in combination with cyclones, are the climate change stressors of the utmost contemporary concern for the GBR. Accordingly, this iconic reef system has a very uncertain future.