Highly protected marine reserves can help reduce the impacts of climate change, concludes a new paper released by a team of international scientists led by Blue Marine Foundation (BLUE) trustee Prof Callum Roberts.
Building on the consensus of previous studies which showed the importance of well-managed marine reserves in protecting wildlife and fisheries, this paper considers a less well known, but no less important, outcome of marine protection – its potential to counteract climate change impacts. By absorbing heat and emissions, the ocean has shielded the earth from more extreme climate change, although climate change has had significant impacts on the ocean itself.
Prof Roberts said: “It was soon quite clear that they [well-managed marine reserves] can offer the ocean ecosystem and people critical resilience benefits to rapid climate change.”
Climate change adaptation
The paper begins by outlining compelling evidence of how marine reserves help both ecosystems and coastal communities adapt to key impacts of climate change, describing how reserves and Marine Protected Areas:
- Protect natural defences against sea-level rise, storms and extreme events by preserving the coastal habitats that stabilise shores and reduce incoming wave energy.
- Help counteract ocean acidification by protecting coastal plants that lower local CO2 concentrations through photosynthesis, and by allowing the regeneration of fish populations that are involved in carbon cycling.
- Allow species distribution to change in response to climate change by acting as ‘stepping stones’ for dispersing species, safe ‘landing zones’ for colonising species and refuges for those which cannot move.
- Help offset declining productivity by allowing exploited fish stocks and degraded habitats to recover.
The impact of climate change on the ocean
Climate change impacts are set to increase significantly in the near future, with the Intergovernmental Panel on Climate Change (IPPC) predicting up to a 100% increase in ocean acidity and up to 82 cm rise in sea level by 2100, with devastating consequences for coastal communities.
Furthermore, threats to the oceans are often cumulative, in that ecosystems and organisms which are already stressed by human pressures are more vulnerable to the further stress of climate change impacts. For example, coral reefs which have been denuded of fish are more vulnerable to bleaching caused by warmer water and less likely to recover following a bleaching event. Marine reserves reduce human pressure and so act as an ‘insurance policy’, putting wildlife in a stronger position to adapt to a changing climate.
The evidence that marine reserves can reduce these threats therefore provides compelling evidence for further reserve designations and more ambitious marine protection targets.
Climate change mitigation
The second part of the paper discusses the role of marine reserves in climate change mitigation, as they promote the uptake and long-term storage of carbon from greenhouse gas emissions. The sediment underneath coastal wetlands can store carbon for long periods of time, and marine species, from coastal to deep-sea ecosystems, play a vital part in carbon cycling. Marine reserves can protect these features and their carbon benefits: reserves can protect coastal sediment from human disturbances such as trawling that would otherwise result in the release of carbon from the sediment and safeguard the species that are important within the carbon cycle.
The role that oceans play in storing carbon should provide further powerful incentive for large-scale marine conservation on the basis of its ability to lessen the climate impact of emissions. Following the United States’ withdrawal from the Paris climate change agreement, the world is in greater need than ever of innovative ways to reduce emissions.
This paper provides good reason to consider marine reserves a practical and cost effective solution, hitherto overlooked, according to the authors. Co-author Beth O’Leary, of the University of York, states that the research shows reserves to have benefits from ‘local to global scales, improving the outlook for the environment and people into the future.’
The authors of this paper note that reserves with five key characteristics – large size, no-take, well enforced, long-established and isolated – will produce the greatest benefits, where these are an appropriate local management decision.
Charles Clover, executive director of BLUE, said: “This study provides encouraging evidence in support of BLUE’s advocacy of large marine reserves such as those around the UK Overseas Territories, and should provide impetus for much needed further reserve designation around the world.”
Prof Callum Roberts, lead author of this paper and trustee of BLUE, said “Large-scale ocean protection in highly protected marine reserves doesn’t just safeguard rich habitats and wildlife. It will build resilience against climate change impacts, safeguarding ocean life and the interests of the people who depend on it. BLUE’s efforts to create marine reserves are a smart investment in the future of our planet.”
Despite the clear benefits of marine reserves demonstrated by this study, currently only 3.5% of the ocean is officially set aside for protection, far below the 30% by 2030 recommended by delegates to the IUCN’s 2016 World Conservation Congress, though there is thought by now to be around 6 per cent in the pipeline for designation. The evidence collated in this paper provides governments with a further incentive to designate large-scale marine protected areas.
However, the paper also notes that reserves alone are not enough to save the oceans and they must be used as a vital part of a portfolio approach alongside sustainable fishing practices, as BLUE is developing in Lyme Bay and elsewhere.
Image credit: Ultraphyte