Terms of Reference
ESSAS Working Group 1: Regional Climate Prediction (WGRCP)
Ecosystem Studies of Sub-Arctic Seas (ESSAS)
28 February 2007

Introduction
A major goal of ESSAS is to predict the potential impacts of climate
variability on the sustainable use of the sub-arctic seas. ESSAS has elected toemploy a comparative approach, investigating in each of the sub-arctic seas
which energy pathways appear particularly vulnerable to decadal and longerterm climate change. The ecosystem response to climate can be non-linear withthresholds, have complex interactions between species, and different species
impacts from similar climate fluctuations. Reducing uncertainty about the futurestates of ESSAS ecosystems depends on knowledge of the response of theecosystem to changes in climate and a quantitative ability to project futureclimate states. The first task represents understanding and modeling the complex
linkages between climate variables and species distributions and is a primary
focus of the other two ESSAS Working Groups (ESSAS Working Group 2:
Biophysical Coupling Mechanisms and ESSAS Working Group 3: Modeling
Ecosystem Responses).
A Goal of the Working Group on Regional Climate Prediction(WGRCP) is to provide quantitative estimates of the magnitude and uncertaintyof future climate change for the ESSAS regions, and the frequency distribution ofnatural variability, such as the well known ecosystem reorganization of the North
Pacific in the mid-1970s and historical interdecadal variability in the marginalseas of the North Atlantic. Climate elements known to be crucial to ESSAS
ecosystems include sea ice cover, ocean temperature, circulation, andstratification.
A major resource for the development of future climate scenarios is therecently available results from 22 state-of-the art coupled atmosphere-ocean
climate models which are part of the Intergovernmental Panel on Climate
Change (IPCC) Fourth Assessment Report (AR4). A preliminary investigation
has shown that a subset of these models represents the physical forcing inseveral ESSAS ecosystems reasonably well based on comparison with in situ
data for the late 20th century. There are several factors that lead to theperceived credibility of future climate scenarios from climate models, including
the differences between models, validation exercises for different physicalvariables, and matching the spatial scales that are important to ecosystem
biology.

Tasks
1. Evaluate the credibility of the 22 IPCC models as applied to each of thedifferent ESSAS regions based on comparison of 20th century hindcastswith data, and model to model consistency and physical reliability in theirforecasts. Produce a report which provides recommendations on whichmodels perform well for each region.
2. Working within the larger ESSAS framework, establish which seasons,regions and variables are most important to potential ecosystem shifts
and provide report on future scenarios and confidence estimates of these
conditions for different future time horizons. Assess the contributions fromintrinsic climate variability and external anthropogenic forcing.
3. Recommend IPCC models and procedures for downscaling of the model
output for use in regional ocean/ecosystem models.
4. Be a community resource on retrospective and future climate change
issues.

Implementation
1. The Working Group on Prediction shall exist for a period of three years,
ending six months after the 2009 annual meeting of ESSAS.
2. Six to eight members will be chosen from the fields of climate science andnumerical modeling. Input from experts on ecosystem processes will besought through collaboration with ESSAS WG 2 and 3.
3. The development of the proposed products includes conducting
workshops held at the annual ESSAS meetings and will require intersessional work. The purpose of the workshops is to vett and reachconsensus on information made available prior to the workshops from thepublished IPCC Reports and from direct model evaluations provided bymembers.
Expected Results
To ensure the perceived credibility of future regional climate scenarios, wewill develop a white paper after the ESSAS Workshop in 2007 that examines thedifferences between IPCC models, identifies the spatial scales and variables thatare of relevance to ecosystem-effects of climate change, and delineates furthervalidation exercises for different physical variables that have been performed.
After the ESSAS Workshop in 2008, we plan to have a set of climate
predictions for the major ESSAS ecosystems, based on the IPCC climatemodels. These regional climate scenarios will have sufficient credibility that they

can be used by other ESSAS Working Groups as the basis for their ecosystemmodeling efforts.
Membership
A list of the initial members of ESSAS WG 1 is as follows:
James Overland,
Lennart Bengtsson
Paul Budgell
Vladimir Kattsov
Ken DrinkwaterMike Foreman
Hisashi Nakamura
John Walshacting Chair, USA
Germany
NorwayRussiaNorwayCanadaJapanUSA