Models of marine ecosystems can greatly underesti

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Protecting marine ecosystems and fisheries from climate change is a global priority, but a new international study led by QUT finds that our lack of understanding of how marine systems work is muddying the waters.

Researchers from Australia, the United States, Europe and Canada suggest that while marine ecosystem models are the key tool used to understand how climate change could impact the global food chain and fisheries in the future, the representation of the key processes that determine the response of the marine ecosystem to climate change differ considerably between them. They believe this uncertainty could cause models to underestimate the future impacts of climate change on the world’s marine ecosystems.

Dr Ryan Heneghan of QUT’s School of Mathematical Sciences joined with 23 other researchers representing the international marine ecosystem modeling community to produce a landmark paper on marine climate change impact projections.

The result – Untangling the various responses to climate change among models of global marine ecosystems – has now been published in the journal Advances in Oceanography.

“Global warming is already causing significant changes in the structure of marine ecosystems across the world’s oceans. Models of marine ecosystems give us insight into how these changes might impact larger animals and societal services such as fisheries, ”said Dr Heneghan.

“The models in our study generally agree that climate change will lead to the decline of marine animal biomass around the world. However, we do not yet have a clear idea of ​​the magnitude of these declines in the world’s oceans during the 21st century.

“Millions of people depend on the world’s oceans for their food and income. In light of the recent publication of the Intergovernmental Panel on Climate Change (IPCC) report indicating that at least 83% of the world’s oceans are very likely to warm more during this century, it is essential that we were finding a way to be more precise in such a modeling.

“As a community of marine modelers, we undertook this study to get an honest picture of what we are missing in our models that could cause inter-model variation. “

“We know that the impact of climate change on water temperature and primary production will fundamentally alter marine ecosystems. Fish and other marine life will burn more energy in warmer waters, leaving fewer opportunities for growth and reproduction. At the same time, in regions where the primary production of phytoplankton decreases, there will be less food, which will lead to a further decrease in marine biomass. “

Dr Heneghan’s co-authors included Professor Eric Galbraith of McGill University, Montreal (Canada), Associate Professor Julia Blanchard of the Institute for Marine and Antarctic Studies, University of Tasmania, and Associate Professor Derek Tittensor of Dalhousie University, Canada.

They explored the mechanisms behind the diversity of responses to warming and changes in primary production in eight global marine ecosystem models of the Fisheries and Marine Ecosystem Models Intercomparison Project (FishMIP).

“The impacts of climate change in our models come primarily from changes in temperature and primary production, so we have isolated the impacts of warming and changes in primary production on our model projections of marine animal biomass and structure of the sea. ‘ecosystem,’ said Dr Heneghan.

“Between now and 2100, the evolution of the global biomass of marine animals in our models has ranged from a decrease of 30% to a slight increase of 5%. In all models, there were declines in biomass in most of the world’s oceans, but models disagreed on where, why, and by how much marine biomass would decline under climate change.

“We are also now aware that many models take an optimistic approach to how energy moves through the marine food chain, which overlooks the possibility that climate change could further harm ecosystem functioning and cause disruption. greater biomass declines than our models currently project.

“Attempting to sum up the great complexity of the global marine ecosystem into a handful of equations is extremely difficult and modeling the global marine ecosystem is a relatively new area of ​​research; our oldest models are just over 10 years old, while the climate modeling community was developing its first models over 40 years ago.

“There is a lot of work to be done, and we are excited about the roadmap this study provides the scientific community to increase our understanding of the world’s magnificent marine ecosystems. “

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A PDF is available or read the full document online: Untangling the various responses to climate change among models of global marine ecosystems.

Climate change is also on the agenda of QUT Sustainability week (23-27 August).

Media contact:

Amanda Weaver, QUT Media, 07 3138 3151, [email protected]

Outside opening hours: Rose Trapnell, 0407 585 901, [email protected]


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