Climate Change Thematic Assessment

Impact of marine climate change on ecosystem services

Marine climate change has an impact on most ecosystem services. In many cases, this is directly due to climate change, while in some cases the impacts may be more indirectly due to humanity’s response to the climate emergency (for example, offshore renewable energy developments and mineral extraction).

The marine environment provides goods and services that are valued by our society, either in a direct monetary way or intrinsically. These ecosystem services originate from both living and non-living processes within the marine environment and can be divided into four categories: provisioning, regulation, maintenance and cultural (see: Ecosystem Services Descriptions). Recent reports by the Intergovernmental Panel on Climate Change (IPCC) and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) have concluded that globally, ecosystem services from the ocean will be negatively impacted by climate change, with greater losses anticipated at higher levels of global warming (Pörtner et al., 2014; Hoegh-Guldberg et al., 2018; Bindoff et al., 2019; IPBES, 2019).

The ocean provides arguably the greatest ecosystem service in the climate- change context by alleviating the impacts of global warming across all components of the Earth system (climate regulation). The extent of the biotic and abiotic climate regulation achieved by the ocean in absorbing the greenhouse gas CO₂ and absorbing the excess heat in the Earth system cannot be overstated: it has absorbed 89% of the excess heat since the 1970s (von Schuckmann et al., 2020) and every year absorbs at least a quarter of the carbon dioxide (CO₂) released to the atmosphere from human activities (see:  Ocean Acidification Other Assessment ).

While climate regulation may be the ecosystem service linked most directly to climate change, ecosystem impacts have been described in almost every Thematic Assessment of the QSR 2023, and therefore climate change will likely have an overarching impact on all ecosystem services. The following two examples illustrate potential impacts on ecosystem services, although many more could be listed. First, the anticipated rise in local sea levels will increase requirements for coastal protection. Local sea-level rise may, however, reduce the ability of existing habitats to provide adequate protection. Second, changes in the ocean climate may cause distributional shifts in fish species. This may lead to a reduction in the provision of wild fish biomass.

A recent climate change assessment in the adjacent Baltic Sea (Climate Change in the Baltic Sea, 2021) found that most ecosystem services are expected to reduce because of climate change, although the exact changes in ecosystem services due to climate change are difficult to predict due to uncertainty about future non-climate pressures. The exception to these negative impacts are cultural services related to marine and coastal recreation and tourism, which could benefit to some extent from the impacts of climate change through higher air and sea temperatures and longer seasons. The cumulative effects of other anthropogenic pressures (such as eutrophication, pollution, fishing and aquaculture) have the potential to further reduce ecosystem services by offsetting opportunities or strengthening impacts. Efforts to increase resilience (e.g. protection and restoration) could help maintain or even improve ecosystem services under global warming.

While other Thematic Assessments have applied a link-based methodology, this would have resulted in unclear linkages in the case of climate change owing to the countless interconnections. Therefore, the methodology in this Thematic Assessment does not follow the harmonised approach adopted in others. Instead, in order to further investigate the impacts on ecosystem services, a more general scoring system was attempted by the OSPAR Climate Change Expert Group, based on expert opinion. 

A workshop was held on 19 August 2022, with representatives from Belgium, Iceland, Ireland, Sweden and the United Kingdom, and observers, who were all members of the OSPAR Climate Change Expert Group. During the workshop, the 11 participants were asked to select one of the following six categories to describe the response to climate change by each ecosystem service (these were assigned a score between 0 and 5 in the subsequent analysis): no response (0), unknown (1), no impact (2), some indirect impact (3), some direct impact (4) or strong impact (5). Table I.1 shows the responses for each category as a percentage of respondents (columns 3 to 8), as well as the weighted average score (second column). An example of direct impact from climate change on the ecosystem service under consideration would be where increased temperatures changed finfish distributions or sea level rise caused a change in coastal protection. Indirect impacts were those where the ecosystem service was affected by a sequence of processes (e.g. sea-level rise would create a need for greater coastal protection, which would require more marine aggregate extraction). Future work could further explore how to quantify the impacts of climate change on ecosystem services in the OSPAR Maritime Area, and should draw on a larger participant pool if done through expert opinion.

Experts from the OSPAR Contracting Parties consider climate change to have a direct or strong impact on most of the ecosystem services (Table I.1). Seven ecosystem services were seen as being impacted directly by climate change (average score of 4 or above – blue shaded rows in the table), namely coastal protection by coastal habitats, wild fish and other natural aquatic biomass and related raw materials, nursery population and habitat maintenance, (global) climate regulation, regulation and maintenance of marine food webs, water quality regulation, and mediation of waste, toxics and other nuisances by non-living processes. Cultural ecosystem services were not considered to be so strongly impacted, although this could be due to the bias of expertise (natural sciences, rather than social sciences). The group agreed by consensus that the impact of climate change on the provision of genetic material constituted a knowledge gap.