Although changes are occurring, currents in the Region continue to connect species and habitats and transport nutrients. Longer-term changes to currents due to climate change are expected.

In the past 5 years, cyclone activity has been relatively low. However, large variation in the numbers of cyclones is expected, and cyclones remain one of the most important drivers of ecosystem change in the Region. A longer-term trend may be emerging of decreasing cyclone numbers and increasing average intensity.

Over the past 5 years the average annual freshwater inflow across the Catchment has been just above the long-term average and shown regional variability. Documented and projected changes in rainfall are affecting this process over decades.

Sediment loads delivered during flood events, and resuspension of legacy sediments continue to contribute to the poor state of many inshore coastal and inshore marine ecosystems. Since 2019, some areas have seen improvements in sediment exposure, but other inshore areas continue to be affected by resuspended and catchment-derived sediments.

Sea level has been rising over recent decades, leading to increases in the frequency of high-tide flooding events. Year-to-year changes remain small in the context of inter-annual natural variability. Impacts of sea-level rise will increase in coming decades.

Average sea surface temperatures within the Region have continued to increase over the past 5 years, and record high temperatures were recorded in February 2020. Marine heatwaves occurred in 2020 and 2022, triggering mass coral bleaching in both years, although relatively limited coral mortality. Another mass coral bleaching event unfolded in early 2024, after the end of the 2019 to 2023 assessment period. 

The availability of light at the seabed is below optimum levels in several nearshore locations across the Region, although light levels across most inshore areas have generally remained stable or improved over the past 5 years.