Lead Proponents: Katrin Rehdanz (Kiel Institute for the World Economy and CAU, Kiel), Martin Quaas (CAU, Kiel)
Ocean Acidification (OA) has been gaining increasing recognition in the policy circles recently, due to an increasing number of studies on biological and ecological impacts of OA (e.g. Turley et al. 2010). However, estimates of socio-economic impacts are still almost absent (Brander et al. 2009, Cooley and Doney 2009, Cooley et al. 2011, Narita et al. 2011), although such impacts constitute key information for formulating international policies for greenhouse gas emission reduction as well as for climate engineering and strategies for adaptation. Hence, research on socio-economic impacts of OA has strong policy relevancy.1
The oceans provide goods and services, which are used directly and indirectly by human societies and economies. These include food and health, energy, mineral resources and system services. Ocean services include ecosystem services (e.g. fish and seafood, biodiversity, tourism) as well as the role of the ocean in the climate system. Fig. 5.1 provides an overview of categories of ecosystem services including those of the ocean.
Among the economically most important ocean services are CO2 storage (a regulating service) and fisheries (a provisioning service). In the year 2008, the oceanic carbon content increased by 2.3 +/- 0.4 Gigatons (Gt) of carbon, equivalent to 8.4 Gt CO2 (Le Quéré et al. 2009). At the current price of about 10 Euros for a ton of CO2 emissions in the European Union Emissions Trading Scheme, which is a very conservative estimate of the social costs of CO2 emissions, a one percent decrease, or increase, of this service of the ocean would generate a cost, or value, of 0.84 billion Euros per year. The world-wide marine capture fisheries land about 80 million tons of fish per year, generating revenues of about 65 billion Euros per year, but also exerting a huge impact on marine ecosystems (World Ocean Review 2010).
Ocean acidification interacts with these economically important ocean resources and services (Fig. 5.2). Most directly, OA is a consequence of the use of the oceans as a sink of anthropogenic CO2. However, the quantity of CO2 stored in the oceans is also affected by ocean change, including the processes of acidification and warming, as ocean biogeochemistry is affected by these processes. These effects need to be quantified on a global scale and the associated uncertainties have to be assessed.
The way how fish stocks are managed influences the marine carbon cycle (Wilson et al. 2009) with potential impacts on marine CO2 uptake and, hence, OA. There is thus a possible trade-off between the ocean’s provisioning service (fishery yield) and the ocean’s regulating service in terms of taking up anthropogenic CO2. A close interaction of biogeochemical and ecological modelling with a socio-economic analysis is required to elucidate this potential trade-off in a quantitative way.
To ensure that scientific results will be used most effectively in adaptation and policy making, results of bio-geochemical models and socio-economic analyses have to be shared with affected stakeholders, preferably beginning at an early stage. In addition to valuing changes in ecosystem services in objectively derived monetary terms, it is advisable to let stakeholders value their perceived potential damage on their own. It is very likely that stakeholders are then much more willing to take ownership of the problem of OA, which greatly enhances the motivation for participating in mitigation and adaptation measures.
The general objective of Consortium 5 is to assess and quantify how OA interacts with the provision and use of ocean services, notably with the services of oceanic CO2 storage and fisheries, to reduce the scientific uncertainties associated, and to inform stakeholders about potential impacts and engage them in discussions about options for adaptation.
For CO2 storage, several studies already exist that quantify the effects in physical terms using global biogeochemical ocean models. Our main interest is to assess and reduce the uncertainties associated. Work package 5.1 will focus on uncertainty of model predictions and aims at improving the performance by means of data-based model assessment. Work package 5.2 will assess the effect of environmental variability on the oceanic carbon sink within a global biogeochemical ocean model.
The impact of potential consequences of OA on phytoplankton C:N ratios and hence on the food quality and food web dynamics will be investigated in Work package 5.3, which will also investigate potential effects of changes in fishing pressure on zooplankton mortality and, eventually, on the oceanic biological carbon pump.
The effect of OA on fisheries and other services is much less clear. Ocean acidification and warming (OAW) is likely to have an impact on the stock dynamics of commercially important fishes, as it will probably alter recruitment success, growth, size and extension of suitable habitats (Beaugrand 2009). OAW thus will have implications for fisheries catch potential via impacts on ecophysiology and plankton dynamics (Cheung et al. 2011). These effects on fish stocks and reproduction still have to be quantified in physical terms. To assess the economic impacts of OAW in fisheries, these effects have to be incorporated in ecological-economic models, and the economic effects in terms of changing fishing opportunities have to be assessed.
The existing economic studies point to small impacts of OA on global welfare compared to the impact of climate change (Brander et al. 2009, Narita et al. 2011). However, on the regional or local level significant differences exist but little detailed knowledge exists. Work package 5.4 will focus on two specific environments taking into account location-specific characteristics and different levels of economic development. Moreover, while the aggregate effects on a global scale may be small, there may still be significant local changes in fisheries incomes (for example due to OAW-induced movement of fish stocks), and the effects may strongly depend on the management regime. Work package 5.5 will address these questions and quantify the aggregate and distributional effects of OAW on commercially important cod fisheries.
Differences exist among regions and countries regarding vulnerability and adaptive capacity. An indicator is location, since there is a strong regional variation in the ocean’s buffer capacity and the sensitivity to acidification. Affluence is another important factor. The adaptive capacity of a relatively rich country in the tropics may be higher and therefore the impacts lower, compared to a less developed country in the temperate climate zones. For a developing country in the tropics other issues such as increase in population, public health and education are likely to be more relevant. If OA would affect food security, it would be an additional reason of concern.
Even less is known about a potential feedback of fisheries on OA, although it is well known that fisheries exert a strong impact on marine ecosystems, and some effects on the oceanic carbon cycle have been quantified before (Wilson et al. 2009). A feedback on OA may exist if trophic cascades from fish preying on zooplankton and phytoplankton affect biological production and the oceanic biological carbon pump at a significant scale. Work packages 5.3 and 5.5 will cooperate in studying these feedback effects attempting quantification at the global scale.
Impacts on ecosystem services are region-specific and valuation is depending on local, social, and cultural circumstances. Also, impacts can only be quantified with substantial uncertainties, further complicating the process of adaptation and policy formation. However, adaptation strategies need to be knowledge driven and need to find a broad support among stakeholders. Work package 5.6 will approach this issue with a regional focus on the habitats of two interacting cod species in the North Atlantic.
Research approaches :
The main research approach employed is numerical modelling, in particular using global biogeochemical models and ecological-economic models for fisheries.
In work package 5.1, data-based model assessment will be used to evaluate and calibrate global biogeochemical models used for predictions of oceanic CO2-storage.
In 5.2, the impact of environmental uncertainties on carbon storage and acidification will be assessed using a global biogeochemical ocean model.
In 5.3, the impact of OA on biological processes and the feedback of varying fish stock abundances on OA will be studied by means of the UVic Earth System model.
In 5.4, the impacts of OA on mollusc fisheries at the German/Danish coast and its economic implications will be studied in numerical models.
In 5.5, an ecological-economic model of the different cod fisheries that incorporates the effect of OA on recruitment and fish growth will be used to study the efficiency and distributional impacts of OA under various management regimes. The feedbacks between fisheries and OA will be studied using a similar model at a global scale that is coupled to the Earth System model of 5.3.
In 5.6, involving stakeholders will be facilitated by aggregating the results from work packages in consortium 5 and consortium 4 into a comprehensible frame for presentation and discussion with stakeholders at two workshops (preferably related to the annual BIOACID meetings). Within the model frame, stakeholders will be encouraged to explore different scenarios with varying potential impacts on ecosystem services.
In addition, we will use empirical methods to assess the economic significance of OA effects. In work package 5.4 we will employ a survey approach with choice experiments to evaluate potential negative values of OA on coral reefs and the related services in Papua New Guinea.
Work package 5.6 will additionally employ stakeholder participation approaches and will use discourse-based measures for evaluating OA impacts on ocean services and for deriving options for a resilient management.