Changes in extreme ocean wave heights under 1.5 °C, 2 °C, and 3 °C global warming

Abstract

This study inspects the global changes in seasonal extreme ocean wave heights under different levels of global warming (1.5 °C, 2 °C, and 3 °C) based on statistical wave projections derived from CMIP5 multi-model simulations. The results show robust increases in wave extremes up to 15% (∼1 m) over Southern Hemisphere high latitudes and tropical Pacific, particularly at 3 °C warming. Strong seasonality is observed, especially for the North Pacific. Under higher warming, stronger increases are identified in both amplitude and area of extreme wave heights. The change in magnitude translates into shorter return intervals of extreme wave events in a warmer world, particularly at 3 °C warming. Differences between 1.5 °C and 2 °C worlds reveal potential benefits of limiting global warming over large regions of global ocean. Strong inter-model relationships indicate that wave height increases are associated with intensified climate mode variability, particularly the Southern Annular Mode and El Niño–Southern Oscillation, in a warmer world. An important implication is the potential impact of increased wave extremes on West Antarctic ice shelves with respect to calving and associated loss of buttressing, which would facilitate sea level rise in a warmer world.

Keywords

• Extreme waves
• Paris agreement
• CMIP5
• Southern annular mode
• El Niño–Southern oscillation