Ito, S.-I., K. A. Rose, A. J. Miller, K. Drinkwater, K. M. Brander, J. E. Overland, S. Sundby, E. Curchitser, J. W. Hurrell and Y. Yamanaka, 2010:
Ocean ecosystem responses to future global change scenarios: A way forward.
In: Global Change and Marine Ecosystems,
M. Barange, J. Field, R. Harris, E. Hofmann, I. Perry and F. Werner, Eds., Oxford University Press, pp. 287-322.
The overall aim of GLOBEC was "to advance our understanding of the structure and functioning of the global ocean ecosystem, its major subsystems, and its response to physical forcing so that a capability can be developed to forecast the responses of the marine ecosystem to global change". GLOBEC specified four objectives, and objective 3 was "To determine the impacts of global change on stock dynamics using coupled physical, biological, and chemical models linked to appropriate observation systems and to develop the capability to project future impacts". During the GLOBEC era, earth observational networks such as the Global Climate Observing System (GCOS), which includes the Global Ocean Observing System (GOOS), were developed. Although imperfect, this global observational network is providing an unprecedented view of climate change in the earth system, and has increased our understanding tremendously over the past several decades. An increasing number of independent observations of the atmosphere, land, cryosphere, and ocean are providing a consistent picture of a warming world. Such multiple lines of evidence, the physical consistency among them, and the consistency of findings among multiple, independent analyses, form the basis for the iconic phrase of the observations chapter in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC-AR4, IPCC 2007) that the .warming of the climate system is unequivocal.. Moreover, the evidence is strong that, especially in recent decades, human activities have contributed to the global warming. The IPCC-AR4 additionally cautioned that further warming and changes in the global climate system will very likely emerge over the next century.
The climate changes anticipated during the 21st century have the potential to greatly affect marine ecosystems. A major challenge facing the scientific community is to develop modeling and data analysis approaches for determining how climate change will affect the structure and functioning of marine ecosystems. During the GLOBEC era, our understanding of ecosystem structure and dynamic has improved greatly (Chapter 5, deYoung et al.; Chapter 7, Moloney et al.), and new ecosystem modeling approaches have been developed and existing methods improved (see Chapter 5, deYoung et al.). As we look forward, the next step is to use the knowledge gained from GLOBEC as a foundation, as we continue to develop data collection and modeling tools that can make sufficiently confident projections of marine ecosystem responses to future global climate change.
In this chapter, we summarize the available evidence for recent changes in climate effects in the oceans, and the status of our ability to project ecosystem responses to likely future global change. We first present the evidence for changes in the physical and chemical properties of oceans, including changes in water temperature, nutrient supply, mixing and circulation, rare metal supply, transport of plankton, acidification, and sea level rise. We then discuss the evidence for consequent responses of the marine ecosystem to the documented changes in the oceans, organized by trophic level (primary production, zooplankton, and higher trophic levels). Whenever possible, for each trophic level, we include the results of published examples of future projections of ecosystem responses. With this information as the basis, we conclude with a discussion of our vision of the next steps that are needed to develop models capable of projecting ecosystem responses to global change.
To develop future climate projections, assumptions must be made on the levels of population increase and the rates of development (emission scenarios) that, in turn, determine the rate of CO2 build-up in the atmosphere. Many examples of future projections cited in this chapter used emission scenarios taken from the IPCC (SRES: IPCC-Special Report on Emission Scenarios, IPCC 2000), which are briefly described in Figure 10.1. One exception is an earlier IPCC emission scenario, IS92, which was used by several cited studies. IS92a begins in 1990 and assumes an effective CO2 concentration increase of 1% per year. IS92a differs from the SRES scenarios (Figure 10.1) because it starts from 1990 and the many economic and political issues during 1990.s are not incorporated. IS92a can be roughly thought of resulting in CO2 concentrations in 2100 similar to that of A1B, although the emission scenario is very different and intermediate between the SRES B2 and A2 scenarios (IPCC 2000).
We note that we use the terms global climate change and global change throughout this chapter to refer to anthropogenic-induced climate changes. In many instances, and especially with the examination of historical data, we emphasize that the changes in the properties and biota of the oceans reflect various mixtures of local, regional, and global variation and trends in climate. We cannot attribute all of the documented changes or responses to global scale phenomena, nor can we infer the role of anthropogenic versus natural influences.