U'S' Climate Change Science Workshop

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Climate Variability and Change
Chapter 6
Draft Strategic Plan

• U.S. Climate Change Science Workshop
• December 04, 2002

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CVC Working Group
Lead Authors Contributors Randall
Dole (Co-Chair), NOAA Anjuli Bamzai, NOAA Jay
Fein (Co-Chair), NSF Steven Meacham, NSF David
Bader, DOE Tony Socci, EPA Ming Ji,
NOAA James Todd, NOAA Tsengdar Lee, NASA David
Legler, CLIVAR Michael Pavich, USGS
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Background
Results from climate science research

• It is likely that the rate and duration of global
  warming during the 20th century exceeds natural
  variability of the past 1000 years.

• Model simulations that include estimates of
  natural and anthropogenic forcing are able to
  reproduce large scale aspects of the observed
  surface warming over this past century.

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Background (cont.)

• Model projections based on a range of possible
  scenarios suggest that climate changes over this
  century will be larger than what has been
  observed up until now.

• Due to natural processes, rapid climate changes
  can occur in decades or less, yet last for
  centuries or longer.

• Major advances in observations, understanding,
  and modeling of El Niño Southern Oscillation
  (ENSO), which have given the world an
  unprecedented opportunity to prepare for and
  reduce vulnerabilities to this major natural
  climate phenomenon.

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Some major challenges

• Continuing uncertainties on climate system
  sensitivity to various feedbacks (e.g., clouds,
  water vapor, snow).
• Several natural modes of climate variability have
  been identified and described, but their
  predictability is uncertain.
• Need to improve understanding of whether and how
  human impacts may alter natural climate
  variability.
• Do not yet have confident assessments of the
  likelihood of abrupt climate changes.
• Insufficient understanding of effects of climate
  variability and change on extreme events.
• Limited capabilities at regional scales.
• Need better means for identifying, developing,
  and providing climate information required for
  policy and resource management decisions.

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Key references

• IPCC Third Assessment Report The Scientific
  Basis (WG1, 2001).
• NRC Reports
• Climate Change Science An Analysis of Some Key
  Questions (2001).
• Global Environmental Change Research Pathways
  for the Next Decade (1999).
• U.S. Climate Modeling Reports (1998, 2001).
• Abrupt Climate Change Inevitable Surprises
  (2002)
• The Atmospheric Sciences Entering the
  Twenty-First Century (1998).
• Making Climate Forecasts Matter (1999).
• A Climate Services Vision (2001).
• Other planning documents, e.g., CLIVAR Science
  Plan.

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Overarching questions

• How are the climate elements that are important
  to human and natural systems, especially
  temperature, precipitation, cloudiness, and
  storminess, affected by variations and changes in
  the Earth system that result from natural
  processes and human activities?

• How can emerging scientific findings on climate
  variability and change be further developed and
  communicated to most effectively meet the needs
  of policymakers and public and private sector
  decisionmakers, in order to enhance human
  well-being, strengthen the economy, and reduce
  risks and vulnerability of climate sensitive
  activities and resources?

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Major Questions
1. What is the sensitivity of climate change
projections to feedbacks in the climate system?
Q1 focuses on the fundamental issue of the role
of climate feedbacks in producing uncertainties
in climate change assessments and projections.

• To what extent can predictions of near-term
  climate fluctuations and projections of long-term
  climate change be improved, and what can be done
  to extend knowledge of the limits of
  predictability?

Q2 focuses on theoretical and practical limits of
predictability of the coupled climate system.
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Questions (cont.)

• What is the likelihood of climate-induced changes
  that are significantly more abrupt than expected,
  such as the collapse of the thermohaline
  circulation or rapid melting of the major ice
  sheets?

• Whether and how are the frequencies, intensities,
  and locations of extreme events, such as major
  droughts, floods, wildfires, heat waves, and
  hurricanes, altered by natural climate variations
  and human-induced climate changes?

Qs 3 and 4 emphasize issues of high practical
significance to societies and ecosystems --
abrupt climate change and extreme events.
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Questions (cont.)

• How can interactions between producers and users
  of climate variability and change information be
  optimally structured to ensure essential
  information needed for formulating adaptive
  management strategies is identified and provided
  to decisionmakers and policymakers?

Q5 emphasizes the need for improved mechanisms to
identify and provide climate information that
will better support the needs of the public,
resource managers, and policymakers.
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Some products

• Refined estimates of the role of climate feedback
  processes in affecting climate sensitivity, and
  reductions in known uncertainties.
• Development and extension of critical data sets,
  including paleoclimate data and model-based
  reanalyses, to improve attribution of causes of
  long-term climate variations.
• A new estimate of sea level rise that
  incorporates the most recent ice sheet and
  glacier change estimates.
• An assessment of how climate extremes are likely
  to change over the United States in the next
  century.
• A geographical information system that includes
  data on current extreme events, and locations of
  vulnerable populations and infrastructure.
• Improved climate information for regional
  applications and risk reduction.

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Payoffs

• More certain estimates of the global and regional
  manifestations of future climate changes.
• Increased understanding and confidence in
  attributing the causes of recent and historical
  changes in climate.
• Improved ability to critically evaluate the
  strengths and weaknesses of climate change
  projections.
• Improved understanding of thresholds and
  nonlinearities in the climate system.
• An enhanced capability to evaluate potential
  scenarios of change in both extreme events and
  vulnerabilities, to develop strategies for
  reducing disaster-related losses.
• Improved access to climate information and
  products for addressing regional concerns and
  issues.

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Critical Research Needs

• A high-level international commitment to a
  sustained, long-term observing system of a
  quality adequate for climate research and
  assessments.

• A highly focused and adequately funded modeling
  and prediction activity.
• A research-based infrastructure to develop and
  provide the scientific information required by
  decisionmakers and resource managers, and to
  support national and international climate
  assessments.

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Linkages

• Primary USGCRP linkages are to the Water Cycle,
  Atmospheric Composition, and Carbon Cycle.
  Significant linkages to all other elements.
• Strong linkages to CCRI components of Research
  Focused on Key Climate Change Uncertainties,
  Climate Quality Observations and Monitoring, and
  Decision Support Resources, especially applied
  climate modeling.
• Other critical linkages are to internationally
  coordinated research programs, including the
  World Climate Research Programme (WCRP) and its
  projects, CLIVAR, GEWEX, SPARC, CliC, and the
  IGBP PAGES paleoscience project.