Climate Extremes Summary of proposals to date

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Climate ExtremesSummary of proposals to date

• Howard Cattle
• ICPO, NOCS, Southampton, UK

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Objectives of the cross cut

• Summarize, compare and assess definition(s) of
  climate extremes and develop a common framework.
• Design an intercomparison framework to assess
  models, observations to evaluate changes in
  climate extremes
• Accelerate progress on prediction of climate
  extremes developing capabilities and products
  facilitating practical applications
• Assess and improve the observational and dataset
  framework for study of global extremes
• Determine how extremes are changing/varying and
  why.
• Understand the processes controlling extreme
  climate
• Build capacity in the interpretation of model
  outputs and observational datasets with regard to
  climate extremes
• Develop climate indices for the study and
  monitoring of extremes

JSC-28 voted CHF8k to each of GEWEX and CLIVAR
for this cross cut for 2008. Recognizing limited
resources, where should WCRPs focus be?
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Activities since JSC-28

• Continued CCl/CLIVAR/JCOMM ETCCDI activity, WGCM,
  CEOP Extremes activity
• Sought to scope initial direction of cross cut
  (telecons etc)
• Further exploration of stakeholder interests
  (followed pre-JSC-28 stakeholder consultation by
  ICPO)
• Visits to Munich Re and Swiss Re
• ICPO staff involvement (Anna Pirani -
  insurance/investment) in CIRUN (Climate
  Information Responding to User Needs) workshop
  (Tony B)
• ICPO assistance to Lighthill Risk Network
  Workshop on climate variability
• Consultation with experts at AGU meeting Dec 2007
• Development of plans for two workshops
• Set up draft cross cut website on CLIVAR home
  pages (Anna Pirani) (http//www.clivar.org/organiz
  ation/extremes/extremes.php)
• Input comments (especially from GEWEX) to ICSU on
  its Planning Group Report on Natural and
  Human-induced Environmental Hazards and Disasters

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Outcomes of meetings with Swiss Re and Munich Re

• Swiss Re interest in
• Regional downscaling experiments to help
  understand climate change risk
• Coordinated experiments at sufficient resolution
  to reduce uncertainties in future projections of
  tropical cyclones, floods, winter storms,
  droughts and floods
• Determination of how extremes are changing and
  varying and why
• Participation in WCRP key events
• Munich Re interest in
• Detection of extreme events in the Munich Re
  catastrophe loss data base
• Studies of extreme event clustering
• Information on rainfall probabilities for their
  capacity building efforts
• Collaboration on a map projecting global
  climate-related risk into the future.

No clear way forward on how to develop these
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Lighthill Risk Network Workshop(Lloyds of
London, 2 May 2008)

• Programme developed by re-insurers with advice on
  science contributors from ICPO
• Key topics
• European perils
• European windstorms and latest views on modelling
• European flood
• Science Panel discussion
• Teleconnections (how might they lead to lack of
  independence between insurance claims around the
  world)
• Decadal prediction (how robust is it? does it
  allow for climate change)
• Response from Catastrophe Modelling firms
• Networking session

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Issues emerging from AGU discussion(participants
Lisa Alexander, Gabi Hegerl, Neville Nicholls,
Simon Tett and Francis Zwiers

• The scale discrepancy between models and
  observations
• Improving model representations of extremes
• Internal consistency of extremes, e.g
• Understanding how models of variability influence
  extremes
• The dynamical situations leading to extremes
• Extreme extremes (e.g. hurricanes) and small
  scale weather extremes (tornadoes, hail,
  thunderstorms)
• Data quality and availability
• Detectability and predictability of extremes

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CEOP/GEWEX Extremes Workshop

• Vancouver, May 2008
• GOAL to advance CEOP/GEWEX Extremes effort as a
  significant contribution to WCRP
• Will address extremes arising from climate
  variability in a changing climate
• Includes consideration of various phenomena
  including drought, heavy precipitation and
  floods.
• Primary output an overall assessment of current
  extremes studies and an improved plan to realize
  GEWEX and WCRP objectives

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CIRUN follow-on workshop

• Aimed at bringing together the insurance/investmen
  t sector, the catastrophe modelling climate
  modelling communities, operational NWP centres
  and data archive centres.
• Issues data requirements, modelling needs and
  definition of new research initiatives
• Facilitate a focused discussion of the
  insurance/investment climate information needs
  for coping with extreme climate events in a
  changing climate
• Aim for concrete results in
• Improved data accessibility and usability
• Assessment of observational data needs (extension
  of historical datasets sustained effort in
  maintaining and extending in situ observations)
• Assessment of modelling needs (high resolution
  output, regional modelling, high resolution
  reanalysis products)
• Development of consistent climate extremes
  definitions
• Definition of new research initiatives and
  collaborative opportunities.

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Areas of future research identified in JSC-29
paper

• Continued development of the CEOP extremes
  activity
• Coordination of drought research with US drought
  programme
• Encourage activity to understand how modes of
  variability influence extremes and what dynamical
  situations lead to them
• Seek to reduce uncertainties of model simulation
  of extremes (Modelling Summit expects to address
  this)
• Improve methods of interpreting model output,
  reanalyses and satellite products - how do we
  best compare models and data?
• Develop consistent definitions of extremes
  between between models and observations/scientists
  and practitioners
• Establish regional projects - workshops bringing
  together observationalists, regional modellers
  and planners/decision makers aimed at improving
  the regions ability to reduce risk from
  climate-related disasters

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Present WCRP extremes foci

• CCl/CLIVAR/JCOMM ETCCDI activity
• Development of new indices/develop global indices
  database
• ETCCDI meeting (KNMI, May 2008) to include joint
  workshop with ENSEMBLES (Focus on Extremes in a
  changing climate and workshop on issues of
  scaling - how do we adequately compare observed
  extremes with model output?)
• Proposed near term (decadal cross cut, out to
  2030) climate experiments aims to give guidance
  on the changing risk of extremes
• WGCM International detection and attribution
  group on design of C20 simulations for next IPCC
  includes addressing of issues related to
  detection of extremes
• CEOP extremes study Canadian drought a focus
• US CLIVAR-led activity on US drought (US focus)
• GEWEX/UNESCO global heavy rainfall product at 24
  48 hour accumulation periods, funded by NASA,
  NOAA and UNESCO
• Sea level extremes, sea ice extremes etc

How can we bring these together into
a coordinated cross-WCRP effort, adding value?
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Suggestions received for way forward

• Need for effective support for existing
  activities
• Approach extremes cross cut though limited
  lifetime, focussed Working Groups (following US
  CLIVAR model) e.g
• Working Group on combining observations and
  modelling of extremes - one output a CCl/WCRP
  Guidance Statement on assessing probabilities of
  extremes in a changing climate
• Working group on drought, building on US CLIVAR
  GEWEX efforts
• Approach through proposed workshops
• CIRUN follow-on
• GEWEX/CEOP
• With cross membership of both, these could
  provide a springboard to scope the extremes cross
  cut further
• Set up Task Force on Climate Extremes to define
  way forward
• Build links to WMO Climate Watch

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Thank you
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Some research priorities identified by the WCRP
community

• On indices
• Key issues
• Determine physically-based indices of extremes
• Involve more than one variable at a time
• Link more with societal impacts
• Actions include
• Summarize current indices
• Summarize means through which extremes occur and
  the connections between them
• Improve indices as appropriate
• Assess which, if any, datasets are xcapable of
  providing the needed information.

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Some research priorities identified by the WCRP
community

• Improve simulation of extremes-producing
  processes in models (intense rainfall, tropical
  cyclones, drought, land surface feedbacks,
  blocking etc.)
• However, once models get it right how will we
  know we have arrived because of the state of the
  observing system and large inconsistencies in
  extremes between analyses constrained to greater
  or lesser extents by observations.

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Space and time scales and language

• Extreme events - can be defined through extreme
  values of certain important variables (often
  causing damage)
• Simple indices of extremes based on time series
  of annual counts or exceedances
• E.g., number of exceedances above 90th percentile
• Some studies use thresholds as high as 99.7th
  percentile
• Extremes can cover a very wide range of space and
  time scales. Range from very small scale
  (tornadoes) to large scale (eg drought)
• Language used in climate circles not very
  precise.
• Severe events - create large losses in measures
  (e.g. life)
• Rare events - low probability of occurrence.
• High impact (but not really extreme)
• Unprecedented events (in the available record)
• Paper by D Stephenson seeks to clarify
  definition, diagnosis and origin of extreme
  weather and climate events
• Introduces concepts of acute and chronic
  extremes

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Climate Extremes - Issues raised from initial
stakeholder consultation

• Data Accessibility reanalysis data, IPCC AR4
  output
• Need for observational data continuous
  records, improvement of spatial coverage, need
  ground wind speed measurements, encourage the
  release of data by countries, eg in Africa.
• A discussion on the quantitative and qualitative
  definition of Extremes.
• Assessment of Methods deterministic/probabilist
  ic modelling approaches and their reliability.
• Assessment of extreme event clustering in space
  and time and whether this is changing with
  climate change.
• Widen scientific collaboration to address the
  impact of deforestation, desertification,
  urbanisation, land use changes etc.