Download S1_Ammann_WIPS_Modeling – ppt

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WIPS – The Earth's Climate System
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The Earth’s Climate System
Challenges and Advances with Geologic Data and Modeling Partnerships
Caspar M. Ammann
National Center for Atmospheric Research, Climate and Global Dynamics Division
[email protected]
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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 Techniques
open doors to Geologic Time
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IGY: Weather / Climate
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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
Deep Time
Quaternary
Holocene
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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
"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
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Is this still simply a “geophysical
experiment”?
Greenhouse Gas Concentrations last 600,000 years
CO2 - 20,000 years
Methane
Temperature
CO2
Rate of Change
unprecedented for probably
millions of years!
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IPCC 2007
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3 Decades in Earth Observations and Change
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.”
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Why is it not natural?
Climate has
always been
changing,
naturally …
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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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Slide 15
Changes Across Scales
Effect on Extreme Precipitation
1900
2003
Global-wide Glacier Collapse
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Global Sea Level Rise
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Slide 17
Models are now “Partners” to Data
~150 km
Viner (2002)
Model Computation:
- 15 minute time steps
- 1 quadrillion calculations /yr
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Slide 18
Climate Models circa early 1990s
Global coupled climate models
in 2006
Global models in 5-10 yrs
Regional models
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Continuously Improved Models
CCSM: Climate Simulations
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Slide 20
Performance of CCSM-3
Surface Air Temperature
El Niño-Variability
Model
Model
Observations
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Observations
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High Resolution Ocean Models
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Climate Modeler's Commandments
by John Kutzbach (Univ. of Wisconsin)
1.
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10.
Thou shalt not worship the climate model.
Thou shalt not worship the climate model, but thou shalt honor the climate
modeler, that it might be well with thee.
Thou shalt use the model that is most appropriate for the question at hand.
Thou shalt not change more than one thing at a time at first.
In making sensitivity experiments, thou shalt hit the model hard enough to make it
notice you.
Thou shalt not covet fine-scale results with a coarse-scale model.
Thou shalt follow the rules for significance testing and remember the model's
inherent variability.
Thou shalt know the model's biases and remember that model biases may lead to
biased sensitivity estimates.
Thou shalt run the same experiment with different models and compare the results.
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.
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Slide 23
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
All
forcings
Natural
only
Meehl et al. 2004
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Future Climate Projections
Note: These are “What If” Scenarios, not predictions
A2: 2020s
A2: 2090s
IPCC, 2007
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Simulation 20th and 21st Century Climate
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
•…
NCAR CCSM: Gary Strand
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Slide 27
Sea Ice : Observations and Model Projections
2000
~2040
September Sea Ice Extent: Abrupt change potential!
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Are we over-blowing the problem?
… most likely not …:
- emissions faster than projected
-
carbon cycle and nutrientsCanadel et al. 2007
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 …
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Slide 29
Goal of seamless understanding Past-Present-Future
Ammann et al., 2007
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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
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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
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Paleo Analogs for future temperatures?
Future climates might resemble the past >40 Mio yr ago
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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
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Possible new CCSM Components for AR5
• 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
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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
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Changes in Seasonal Cycle of Snowmelt (T)
and shifts in Jet-stream with change in Precip (P)
Water from Snowpack in dry summer season?
Barnett et al. 2008
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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!
• 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?
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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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Slide 42
The Great Challenge:
Balancing Climate and Energy Needs
Thank you!
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Slide 43
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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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Slide 45
Challenge:
Polar Temperatures during Warm Climates
(Equator - Pole Gradient : High latitude warm but tropics cool?
A data or a model problem?)
Proxy
Record
Models
Future
Present
Huber and Sloan, 2001
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Slide 46
Subtropical drying in with large scale warming?
Can this fundamental concept be confirmed in past climates?
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