Projected wave climate of Bass Strait and south-east Australia by the end of the twenty-first century

Abstract

Abstract A high-resolution third-generation wave model based on unstructured grids, WAVEWATCH III (WW3), was used to study the projected future wave climate of Bass Strait and south-east Australia under two different greenhouse gas emission scenarios (SSP1-2.6 and SSP5-8.5). The wave model, forced with winds from the Australian ACCESS-CM2 Global Climate Model, shows good agreement with coastal long-term buoy observations and an independent WW3 hindcast dataset over the historical period 1985–2014. The projected mean significant wave height ( $$H_{s}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>H</mml:mi> <mml:mi>s</mml:mi> </mml:msub> </mml:math> ) for SSP5-8.5 by the end of the twenty-first century (2071–2100) shows a robust increase for the majority of the domain, but a decrease in nearshore regions, mainly due to projected decreases in local wind speed. The increase in $$H_{s}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>H</mml:mi> <mml:mi>s</mml:mi> </mml:msub> </mml:math> for SSP1-2.6 is relatively small. Seasonal variations show that $$H_{s}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>H</mml:mi> <mml:mi>s</mml:mi> </mml:msub> </mml:math> (SSP5-8.5) is primarily influenced by Southern Ocean swell in spring and winter and local winds prevail in summer and autumn. H s percentiles show a stronger increase in extreme wave climate for SSP5-8.5 than for SSP1-2.6. Extreme value $$H_{s}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>H</mml:mi> <mml:mi>s</mml:mi> </mml:msub> </mml:math> for SSP1-2.6 shows a projected decrease in western regions of the domain and an increase in the east. Extreme value $$H_{s}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>H</mml:mi> <mml:mi>s</mml:mi> </mml:msub> </mml:math> for SSP5-8.5 shows a decrease in the nearshore areas of Victoria. This study shows that projected wave climate changes in south-east Australia may have potential implications for Tasmanian and Victorian coastline stability.