Marine Heat Waves - Global Patterns of Impacts and Risks

The global ocean has warmed significantly in recent decades, causing shifts in species' distributions and alterations to the structure and functioning of marine communities and ecosystems. Superimposed onto this gradual warming trend are discrete extreme climatic events, where seawater temperatures may be considerably higher than normal for periods of weeks to months. As such, some of the highest seawater temperatures on recent record have been observed during contemporary warming events, which can drive step-wise changes in the distribution of biodiversity and the structure of entire ecosystems. In general, discrete extreme climatic events are increasing in frequency and intensity as a consequence of anthropogenic climate change, so that understanding and predicting biological responses to 'events', rather than 'trends', is becoming increasingly important. In the terrestrial realm storms, droughts, floods and heat waves can have catastrophic effects on ecosystems, with significant socio-economic ramifications, but knowledge of how extreme climatic events shape marine ecosystems pales in comparison.

This project will bring together an international team of scientists to collate evidence on the physical properties of marine heat waves and their biological impacts. The team will analyse existing sea temperate records to examine trends in the frequency and magnitude of short-term extreme warming events and use sophisticated ocean climate modelling approaches to predict the frequency of marine heat waves in the future. The team will then synthesise information on how marine heat waves affect the distribution of life in the sea, and make predictions of the structure of marine ecosystems impacted by future warming events. The project will significantly advance our understanding of how heat waves may affect marine biodiversity patterns and the sustainability of ecological goods and services provided by marine ecosystems.

This project will generate an integrated and comprehensive body of information on the physical properties and biological impacts of discrete warming events, from organisms to ecosystems. The outcomes will be of direct benefit to those interested in the sustainable management of living marine resources and biodiversity (e.g. marine managers, conservationists and policy makers), in a number of different geographical regions. The knowledge gaps that will be addressed by this project have been identified by recent Marine Climate Change Impact reports for both the UK and Australia, which explicitly state that there is a pressing need for a robust examination of temporal trends in discrete warming events in our oceans. The core research team have strong links MCCIP UK and CSIRO (lead conveners of marine climate change report cards for the UK and Australia, respectively). Close alliances with these organisations will ensure that research outcomes are effectively fed into the report card process, and that information is disseminated to a wide range of end users for maximum impact. Ultimately, the evidence collected by the Marine Climate Change Report card process is required by the Intergovernmental Panel on Climate Change (IPCC), which has highlighted an urgent need for greater understanding of how marine ecosystems respond to both gradual climate change and extreme climatic events. Improved understanding of the likely impacts of climate change on ecological goods and services is vital for informing adaptive management processes and for ensuring the sustainable use of living marine resources. This has direct relevance to millions of people in the UK and elsewhere, as marine environments play an important socioeconomic and cultural role in society.