Written by Jiaxin Shi, Darren Li Shing Hiung, Yuxin Wang, Shujing Zhang, Dr. Zijie Zhao, and Professor Neil Holbrook
Summary
Marine heatwaves are naturally occurring, unusually warm ocean temperature events that can severely impact marine ecosystems and socioeconomic activities. They can be driven by varying factors, including local processes, large-scale climate patterns, and human-induced global warming. Advances in high-resolution ocean models are improving marine heatwave predictions. This is important as global warming drives more frequent and intense marine heatwaves.
Rising air and sea temperatures, driven largely by anthropogenic emissions, have made marine heatwaves longer, more frequent, and increasingly damaging to already vulnerable marine ecosystems. Scientists are working to understand the mechanisms and trends behind these events in a warming world, with a focus on their physical drivers. This research is essential for enhancing prediction systems, enabling stakeholders to take proactive steps to mitigate impacts and safeguard marine environments.
The latest briefing note from the ARC Centre of Excellence for Climate Extremes explores marine heatwaves, their impacts, causes, and how they are being affected by climate change. Download the briefing note below.
The impacts of marine heatwaves
Marine heatwaves have severely impacted key regions around Australia (Figure 1).
Marine heatwaves are periods of extreme warm temperatures in the oceans, occurring when ocean temperatures exceed a statistical threshold, typically the 90th percentile, based on a reference period of normal temperatures known as climatology. This climatology is unique to each location and time of the year, meaning marine heatwaves can occur in any ocean region and during any season.
These events have wide-ranging impacts on marine ecosystems, including harmful algal blooms, coral bleaching, and organism mortalities, posing significant risks to marine biodiversity and the overall health of the oceans.
The ecological damage caused by marine heatwaves can have profound socioeconomic impacts, affecting important ecosystem values provided by our marine environment, such as the provision of natural resources and habitat services. Since the 1980s, the frequency and duration of marine heatwaves have been increasing in most areas of the oceans due to global warming, with certain regions experiencing a higher rate of increase compared to others.
Worryingly, marine heatwaves will likely become more intense and frequent as global average temperatures keep rising, thus becoming an increasing threat to marine ecosystems. Advances in high-resolution models are improving our ability to predict marine heatwaves accurately, which help provide a “preparation window” for taking actions and adapting in advance to minimise the potential impacts.
