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Summary
An understanding of Arctic sea ice is scientific research community.
important because the Arctic plays a role in Accompanying this growing interest is an
influencing not only the global climate urgent demand to increase the pace and
system, but also the global economic system scope of the advancements in predictive
through changes in marine access and capabilities. Added pressure comes with the
natural resource development (Box S.1). reality of the limited resources (e.g., funding
Recent dramatic changes in the thickness and infrastructure) available to enable
and extent of the Arctic sea ice cover, which continued improvement of Arctic sea ice
can be linked to the warming climate, are prediction and the likelihood that, in the
well documented. These changes affect a face of continued warming, the Arctic will
growing community of diverse stakeholders, remain a dynamic environment well into the
including local populations (e.g., indigenous 21st century.
populations), natural resource industries, As tasked by the National Aeronautics
fishing communities, commercial shippers, and Space Administration, the Office of
marine tourism operators, national security Naval Research, and the intelligence
organizations, regulatory agencies, and the community, the committee convened a
BOX S.1
KEY SCIENCE QUESTIONS
· What are the implications of the recent dramatic shifts in the Arctic from predominantly
multiyear ice to first-year ice, and how will the associated complexities of this regime shift
affect sea ice variability and predictability?
· In a rapidly changing Arctic regime, how will forcings and couplings between the various
components of the ocean, atmosphere, cryosphere, seafloor, and land systems modify or
influence the processes governing the characteristics of the sea ice cover?
· What are the impacts of extreme events and feedback mechanisms on Arctic sea ice
evolution and our ability to predict it?
· How will changing Arctic sea ice characteristics and dynamics affect stakeholders on a
variety of timescales, including prediction requirements?
1
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2 Seasonal to Decadal Predictions of Arctic Sea Ice: Challenges and Strategies
workshop with the goal of exploring current promising avenues in addressing the
major challenges in sea ice prediction and most pressing needs.
identifying new methods, observations, and
technologies that might advance seasonal to This deliberately integrative approach
decadal sea ice predictive capabilities would not only help address the challenges
through improved understanding of the identified in Chapter 2, but is also necessary
Arctic system. The content of this report is to effectively implement many of the
largely informed by the discussions held strategies laid out in Chapter 3.
during the workshop and is augmented by In this spirit, there are several key
the committee's deliberations. overarching challenges, not unique to the
A key theme resonating throughout the topic of sea ice prediction, that hinder
report is the importance of a coordinated advancements in our predictive capabilities:
and integrative approach to advance sea ice
prediction. In fact, fundamental to the · Treating the Arctic sea ice cover not in
success of the workshop was a purposeful isolation, but as an integral part of the
approach taken to foster a dialogue between complex Arctic system which, in turn,
polar researchers, agency representatives, is an integral element of the global
and end users. The committee concludes system;
that there is a need for this dialogue to be · Understanding how the recent regime
sustained well beyond the confines of the shift in the Arctic sea ice cover from
workshop format. A committed and predominantly multiyear to first-year
deliberately integrative approach, founded ice affects the processes governing the
on a sustained and coordinated conversation atmosphere-sea ice-ocean system, the
among the user, modeling, and observation power of statistical prediction
communities, is necessary to: methods, the validity of current
numerical models and their
· Identify and address key gaps in our parameterizations, and observational
fundamental understanding of the requirements, including instrument
Arctic environment and its connection design; and
to the global climate system; · Clearly defining the needs of the
· Balance high-priority stakeholder growing number of stakeholders, many
needs against realistic predictive with additional and more sophisticated
capabilities; requirements, and balancing these
· Foster coordinated support of this needs against realistic predictive
work within the private and public capabilities.
sectors;
· Provide guidance in allocation of The detailed needs of the diverse
resources to support the most stakeholder community are reflected in an
equally diverse set of temporal and spatial
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Summary 3
requirements. Likewise, many of the needs at these longer timescales is to improve the
and challenges associated with sea ice ability to simulate realistic forcings by the
prediction depend on the timescales of atmosphere and ocean using coupled
interest. At shorter timescales (seasonal to climate models at decadal timescales, and to
interannual), predictive capability is thought identify the model variable and/or processes
to reside primarily in an adequate that contribute to unrealistic simulations.
knowledge of the initial ice-ocean state,
although admittedly little information exists In light of these challenges and while
on what constitutes an "adequate recognizing that there are limitations in
knowledge." Challenges on the seasonal current modeling and observational
timescales include: techniques, the committee offers possible
strategies to significantly enhance our
· Understanding the relative strengths and understanding and predictions of the Arctic
weaknesses of the different existing sea ice cover over seasonal to decadal
approaches used to generate seasonal ice timescales:
forecasts (statistical algorithms, coupled
ice-ocean models driven by prescribed · A systematic evaluation of the existing
atmospheric forcing, and coupled seasonal prediction capabilities to
atmosphere-ocean-ice models); establish baseline expectations for
· Establishing specific key observational predictive power and to set the stage
data requirements necessary for defining for advances in predictive capability;
the initial ice-ocean state for seasonal sea · A highly coordinated and integrated
ice predictions; and process-based study of seasonal sea ice
· Providing access to observational data at focused on understanding the impact
fast turnaround times. of the increasing predominance of
younger, first-year ice on sea ice
At longer (decadal and greater) predictions and offering an
timescales, the role of trends in external opportunity to identify, develop, and
forcings (e.g., increasing greenhouse gases) test instruments and observational
and of factors that control the forcings is platforms;
likely to provide some predictive potential · Inform research investments related to
because they account for increasingly large observational needs (e.g., observation
fractions of the change from present sea ice types, locations, and coverage) in
conditions. A critical point of uncertainty support of sea ice modeling and
remains regarding the timescale at which a prediction by conducting an organized
transition occurs between these two regimes, set of model sensitivity studies.
and there is likely to be an intermediate · Enhance the capabilities of numerical
timescale for which the potential models through a coordinated
predictability is low. The primary challenge experiment with multiple models to (a)
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4 Seasonal to Decadal Predictions of Arctic Sea Ice: Challenges and Strategies
identify which variables and processes These strategies are offered as guidance
are critical to simulating a realistic ice toward facilitating a transformative change
cover, (b) determine the sources of in (1) our understanding of Arctic sea ice
climate model drift, and (c) guide predictability on seasonal to decadal
decisions regarding high-priority timescales and (2) our collective ability to
model development needs and the realize and effectively communicate useful
expansion of models to include predictive power. The rate of advancement
additional capabilities and variables of in sea ice predictions will likely be
interest to stakeholders; and determined by the extent to which the broad
· Create a centralized information hub user, modeling, and observational
that facilitates the timely access to communities can achieve a sustained,
observational and modeling results integrative approach to refining and
and encourages sustained implementing these and other strategies.
communication among stakeholders.
