Golden, Mar 14, 2009 WIPS – The Earth's Climate System 1
The Earth’s Climate SystemChallenges and Advances with Geologic Data and Modeling Partnerships
Caspar M. AmmannNational Center for Atmospheric Research, Climate and Global Dynamics Division
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International Geophysical Year 1957/58“A very successful stimulus package for science”
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IGY : Earth Science
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Geomagnetic and Dating Techniquesopen doors to Geologic Time
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IGY: Weather / Climate
Weather / Storm forecasts
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Other breakthroughs: Reconstruction of Ocean circulation, …
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Last 10-20 yrs : Abrupt Earth System Change
WIPS – The Earth's Climate System
Holocene
QuaternaryDeep Time
Initiated / or accelerated by the IGY emerges a much more dynamic picture of the Earth System
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True Global Reach of Humans
Atmosphere Oceans
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"Human beings are now carrying out a large scale geophysical experiment of a kind that could not have happened in the past nor be reproduced in the future.”
Roger Revelle
Is this still simply a “geophysical experiment”?
Greenhouse Gas Concentrations last 600,000 years
IPCC 2007
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CO2 - 20,000 years
Methane
Temperature
CO2
Rate of Changeunprecedented for probably
millions of years!
3 Decades in Earth Observations and Change
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IPCC 2007:“Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely (>90% confidence) due to the observed increase in
anthropogenic greenhouse gas concentrations.”
Why is it not natural?
Climate has always been changing,naturally …
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Golden, Mar 14, 2009 WIPS – The Earth's Climate System Slide 15
Tools to Study Effect of Change in CO2
• Climate Diagnostics and Analysis: Understand coupled Earth System with best observational data / Data Assimilation
• Climate Models: Help to sharpen understanding of geophysical processes
• PALEO: Using time perspective to test and corroborate Goal: Seamless understanding of Past-Present to
build confidence in projections into the Future
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Changes Across Scales
Global-wide Glacier Collapse
20031900
Effect on Extreme Precipitation
Global Sea Level Rise
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Viner (2002)
Models are now “Partners” to Data
Model Computation: - 15 minute time steps- 1 quadrillion calculations /yr
~150 km
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Climate Models circa early 1990s Global coupled climate models in 2006
Regional modelsGlobal models in 5-10 yrs
WIPS – The Earth's Climate System Slide 20
Continuously Improved Models
CCSM: Climate Simulations
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Performance of CCSM-3
Surface Air TemperatureModel
Observations
El Niño-VariabilityModel
Observations
High Resolution Ocean Models
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Golden, Mar 14, 2009 WIPS – The Earth's Climate System Slide 23
Climate Modeler's Commandments by John Kutzbach (Univ. of Wisconsin)
1. Thou shalt not worship the climate model. 2. Thou shalt not worship the climate model, but thou shalt honor the climate
modeler, that it might be well with thee. 3. Thou shalt use the model that is most appropriate for the question at hand. 4. Thou shalt not change more than one thing at a time at first. 5. In making sensitivity experiments, thou shalt hit the model hard enough to make it
notice you.6. Thou shalt not covet fine-scale results with a coarse-scale model. 7. Thou shalt follow the rules for significance testing and remember the model's
inherent variability. 8. Thou shalt know the model's biases and remember that model biases may lead to
biased sensitivity estimates. 9. Thou shalt run the same experiment with different models and compare the results. 10. Thou shalt worship good observations of the spatial and temporal behavior of the
earth system. Good models follow such observations. One golden observation is worth a thousand simulations.
Forcings used in Models
• Present-day direct and indirect forcings
• Past Geographies
• LGM / LIG• Eocene• Cretaceous• Late Permian• Carboniferous
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Simulations of the 20th century: Time
Meehl et al. 2004
Allforcings
Naturalonly
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Future Climate ProjectionsNote: These are “What If” Scenarios, not predictions
IPCC, 2007
A2: 2020s
A2: 2090s
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Simulation 20th and 21st Century Climate
NCAR CCSM: Gary Strand
Models reasonably reproduce changes in:
• Global and continental scale evolution of temperature• Vertical temperature profile• Atmospheric moisture• Heat content of oceans• sea ice retreat in all seasons• …
Sea Ice : Observations and Model Projections
2000 ~2040
September Sea Ice Extent: Abrupt change potential!
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Golden, Mar 14, 2009 WIPS – The Earth's Climate System Slide 29
Are we over-blowing the problem?… most likely not …:
- emissions faster than projected- carbon cycle and nutrients - speed of sea ice retreat?- melting on ice sheets?- weaker trends in models in some responses (precip)?- models in paleo applications: never quite the amplitude …
Canadel et al. 2007
Ammann et al., 2007
Goal of seamless understanding Past-Present-Future
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Last Interglacial (~130 ka): +6m sea level
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Importance of a “Seamless” Integration of Paleo into Climate Change Research
• How well do we understand the cause and magnitude of past changes?
• What effect on the Earth System did past changes have?
• Identify and study analogues to future Climate Change (PETM?, Cretaceous, …)
• Can we develop rigorous benchmarks for climate models on global and regional scales?
• …
Goal: Further improve confidence in models projections regarding magnitude, spatial extent, hydrologic - environmental impact
WIPS – The Earth's Climate System
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Paleo Analogs for future temperatures?Future climates might resemble the past >40 Mio yr ago
WIPS – The Earth's Climate System
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What’s Next? (AR5 ~2013?) Key Role for PALEO!
( 1 ) Long, multi-century projections to study Carbon Cycle Feedbacks, Sea Level Change
( 2 ) Very high-resolution simulations of the next 20-30 years for regional climate change prediction
• Aerosols– Direct and indirect effects
• Chemistry – Radiative and air quality issues
• Dynamic Vegetation– Regrowth following disturbance, human landuse
• Carbon & Nitrogen Cycle– Ocean & land biogeochemistry – Anthropogenic (transient) land use/cover
• Land Ice Sheets– Sea level Rise & Abrupt Climate change
Possible new CCSM Components for AR5
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Future Sea Level and New Orleans (+1m)
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New Focus on Regional Water
Jan. 19, 2009 Colorado School of Mines: Sustainability 37
Changes in Seasonal Cycle of Snowmelt (T)and shifts in Jet-stream with change in Precip (P)
Water from Snowpack in dry summer season?
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Barnett et al. 2008
North American Precipitation and Hurricanes
• 36, 12 and 4 km domains nested into CCSM
• Multi-member ensembles for each period
• Dedicated time on NCAR IBM Power 6 (Bluefire) since July:
~300 Tb of data (to date); 450 Tb total (including earlier runs)
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CCSP 2.1a Mitigation Simulations
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A modern science revolution with Models as Partners in Earth System Analysis: What important answers do we
need from the past!
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• What can be learned about sensitivity of polar ice sheets?
• How quickly can sea level rise?
•How effective is the carbon cycle feedback?
• How much did the tropics or subtropics change?
• How does high atmospheric carbon affect ocean acidity, and how does acidity influence the ocean food chain?
Golden, Mar 14, 2009 WIPS – The Earth's Climate System Slide 42
Climate Change in Perspective
1. Climate has always been fluctuating, and we generally “know” why : Seamless perspective
2. Ongoing Climate Change is real and due to increase in Greenhouse Gas concentrations
3. Models have become partners to field-data and observations. Open questions could provide a platform for enhanced interaction and collaboration providing very important constraints and predictions for decision making
4. There is an urgent need for a constructive dialogue to address the “Great Global Challenge” between Energy Needs and Climate Change
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The Great Challenge:Balancing Climate and Energy Needs
Thank you!
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Paleocene-Eocene Thermal Maximum: A possible “analog” to study future impact on Earth System?
Zachos et al. 2005
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Challenge: Polar Temperatures during Warm Climates
(Equator - Pole Gradient : High latitude warm but tropics cool?A data or a model problem?)
ProxyRecord
ModelsFuture Present
Huber and Sloan, 2001
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Subtropical drying in with large scale warming?Can this fundamental concept be confirmed in past climates?
WIPS – The Earth's Climate System