SECTION V-CENTRAL QUESTIONS AND GOALS
The goal of U.S. GLOBEC is to understand the linkages between climate
variability and long-term change, and the distribution and abundance of
animal populations, including many that are important to society. The
CCS offers an excellent opportunity to accomplish this goal. In the CCS
we can exploit known spatial and temporal variations in physical
processes and biological responses to project population trajectories
under different scenarios of climate change. We can utilize: 1) the
present latitudinal variations within the CCS; 2) interannual (periods
of 2-10 years) temporal variability within the CCS, especially as linked
ENSO cycles; 3) the extensive historical data sets within the CCS, which
can be used to identify natural modes of variability; and, 4) present
day differences between the CCS and other EBCs, to examine ecosystem
responses to differences in the strengths of local and basin-scale
forcing.
The central, over-riding question that drives the proposed U.S. GLOBEC
study of the California Current System is:
How will the distribution, abundance, and life history characteristics
of marine animal populations respond to climatically driven changes in
the CCS?
More Specific Questions
The central question can be expressed as a series of more specific
questions that reflect the broad range of spatial and temporal scales in
which physical-biological couplings in the CCS are manifested. Within
each category we pose, as examples, several even more specific
questions. It should be noted that these questions are not meant to be
exhaustive, but rather to provide the reader with guidelines for the
types of questions that might be investigated during a program examining
the impact of climate change on EBC ecosystems.
Approach to Answering the Questions
Questions regarding the impact of climate change on the CCS ecosystem are
best addressed using a combination of modeling, field work, monitoring
and retrospective data analysis. Our recommended approach to answering
the questions is to identify and understand the most important links, at
present and in the historical record, between the physical processes of
the CCS and key population and ecosystem properties. Subsequently, this
understanding will be applied to predict the responses of these
populations to climate change. Identification of the most important
biological-physical couplings is essential to both modeling and field
efforts, since it is impossible to include every detail of an ecosystem
in any tractable study.
The foundation of this approach will be the study of spatial and temporal
variability in biological processes of the CCS, relative to physical
processes of the CCS that might control biological variability. To help
identify the physical processes to which population dynamics in the CCS
are most sensitive, we recommend several initial activities (modeling,
retrospective and comparative studies) in advance of new field studies.
To aid future field studies, initial activities should also include
technology development. These activities are discussed briefly in
Section II, and in more detail in Section VII. New field studies will
then be directed toward understanding the dominant processes responsible
for present-day and historical distributions and abundances of
populations (and their genetic composition), patterns of transport and
recruitment of critical life stages of both fish and benthic species,
and trophodynamics. Once the relevant processes are identified and
their mechanisms are better understood, they can then be incorporated
into quantitative, descriptive biological-physical models. The accuracy
of these models can be evaluated in part by their abilities to hindcast
historical time series and also predict present-day spatial variability.
We expect this research to lead to a new generation of prognostic
biophysical models, which will continue to be improved as they are used
operationally and in research activities. They should be available for
use with the next generation of coupled ocean-atmosphere GCMs, which
will have higher resolution and provide boundary conditions for the
prognostic ecosystem models. The ultimate goal is to understand the
relevant processes and linkages enough to develop operational,
prognostic biophysical ecosystem models that, when coupled with GCMs,
can be used to assess (and predict) the impact of potential climate
change on the status of living marine resources within the CCS.