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expert reaction to new research on impact of CO2 emissions on oceans and marine life

The effects of climate change on the world’s marine ecosystems is the subject of a paper published in the journal Science, with the authors discussing two scenarios of levels of carbon dioxide emissions and their potential impacts in terms of marine life and associated goods and services.


Dr Alasdair Harris, visiting post-doctoral researcher in marine ecology at the University of Oxford’s Environmental Change Institute and Director of Blue Ventures marine conservation charity, said:

“This is an unequivocal reminder that humanity’s window for altering our current trajectory towards climate breakdown is closing rapidly. The marine impacts of climate change go far beyond ocean warming: by destabilising the fragile chemical composition of our oceans, the survival of life in our oceans as we know it is at stake. Failure to adopt bold and decisive emissions reductions commitments in the forthcoming climate talks will commit us to a pathway to mass extinction of ocean species, with devastating consequences to the marine ecosystems that provide critical services to our growing population of 7.25 billion.”


Dr Clive Trueman, Associate Professor in Marine Ecology at the University of Southampton, said:

“Earth’s climate is driven by the interaction between the atmosphere and the ocean – but the ocean (and its ecosystems) has received far less attention within the IPCC framework. The picture presented in this new study highlights the global scale of impacts on oceans, and shows that almost all ocean ecosystems will be affected by climate change.

“While we can predict how temperature, acidification, oxygen levels and sea level are likely to change in response to CO2 emissions, we know much less about how complex ecosystems will react to these combined pressures. In general, the combination of increased temperature and reduced oxygen is bad for large, active animals and favours smaller organisms. Some animals will be better able to adapt to change than others, but as ecosystems rely on interactions between many different species, effects of change for any particular species are not easy to predict. The message from the fossil record is not encouraging, however – changes in carbon concentrations slower than those currently occurring are associated with the largest mass extinction of all time.

“While uncertainties still remain, it is startlingly clear that if we want to remain in a world with recognisable marine ecosystems, and reliable ecosystem services, the Paris climate negotiations must result in significant and meaningful reductions in CO2 emissions: and that the ocean needs to play a prominent role in these negotiations.”


Prof. Jason Hall-Spencer, Professor of Marine Biology at the University of Plymouth, said:

“It is now abundantly clear that the effects of our CO2 emissions are starting to tighten their grip on the oceans. The combination of rapid warming, acidification and deoxygenation is choking the life out of coral reefs.

“This review screams out to me that the evidence is in and it is not too late for society to benefit greatly from immediate reductions in CO2 emissions. I sincerely hope the high level negotiations in Paris at the end of 2015 are effective and help curb the rapidly accelerating costs of disruption to ocean systems.”


Dr Phillip Williamson, Science Coordinator of the UK Ocean Acidification (UKOA) research programme, said:

“This paper gives a very powerful and succinct summary of what climate change means for the ocean – that until now has been soaking up heat, carbon dioxide and almost everything else that we have thrown at it.

“There are two main messages.  First, that the high emissions scenario would be a disaster for marine life, as well as for ourselves. We sort-of knew that anyway, but it’s good to have the evidence brought together.  Second, that even the stringent emissions scenario for carbon dioxide and other greenhouse gases is not without risks. Knowing that such risks might only be ‘moderate’ rather than ‘severe’, still gives considerable cause for concern.

“Of the four actions proposed to tackle the problem – mitigation, protection, adaptation and repair – only the first can provide a cost-effective response at the scale required to avert damaging environmental and societal consequences, not just for the seas around the UK, but throughout the global ocean.”


Prof. Manuel Barange, Deputy Chief Executive and Director of Science at Plymouth Marine Laboratory, said:

“The paper summarises the findings of the IPCC 5th AR in relation to the world’s oceans.  As such, the findings have gone through a number of review processes that ensure the statements are underpinned with factual information or with the best –imperfect as they are- model predictions.

“The main message is that climate change will continue to affect ocean ecosystems in very significant ways, and society needs to take notice and respond. Some of these impacts are additive, some synergistic, and some antagonistic. The resulting patchwork is difficult to assess and is still subject to many assumptions. However, in essence, significant change will happen, and this change will not be homogeneous across all ecosystems and habitats.  Some ecosystems and their services will benefit from climate change, especially in the short term, but overall the impacts are predominately negative. Geographically, negative impacts are particularly expected in tropical and developing regions, thus potentially increasing existing challenges in terms of food and livelihood security.

“To predict how entire ecosystems will respond is intrinsically challenging, because biological units have evolved over hundreds of thousands of years in very complex ways and in response to continued change. For example, we are only now starting to appreciate the mechanisms of acclimation and evolutionary adaptation that have allowed the diversity of life we observe in today’s oceans. However, there is no doubt that the risks of continuing along a pathway of increased greenhouse gas emissions cannot be overlooked. We disregard potential impacts at our peril, and that peril clearly increases with emissions. We are allowing ourselves to travel a uniquely dangerous path, and we are doing so without an appreciation for the consequences that lie ahead.”


Prof. J Murray Roberts, Director of the Centre for Marine Biodiversity & Biotechnology at Heriot-Watt University, said:

“The oceans are the unsung engines of global climate but human activities are changing them at rates unprecedented in geological history. Gattuso and co-authors lay out the stark implications of carbon dioxide emissions on marine ecosystems and human society. We need to act now to curb emissions and do all we can to limit the impacts of other stressors like fishing and pollution. Given half a chance marine life has the capacity to rebuild, and we need to give that chance now.”


‘Contrasting futures for ocean and society from different anthropogenic CO2 emissions scenarios’ by J.-P. Gattuso et al. published in Science on Thursday 2 July. 


Declared interests

Dr Williamson is employed by the Natural Environment Research Council (NERC), working at the University of East Anglia with project-funding provided by NERC, the Department of Environment, Food and Rural Affairs (Defra) and the Department of Energy and Climate Change (DECC).

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