Golden, Mar 14, 2009WIPS – The Earth's Climate System1

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

[email protected]

Golden, Mar 14, 2009 2WIPS – The Earth's Climate System

International Geophysical Year 1957/58“A very successful stimulus package for science”


IGY : Earth Science



Geomagnetic and Dating Techniquesopen doors to Geologic Time


IGY: Weather / Climate

Weather / Storm forecasts


Other breakthroughs: Reconstruction of Ocean circulation, …


Golden, Mar 14, 2009 January 14, 08

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


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

Is this still simply a “geophysical experiment”?

Greenhouse Gas Concentrations last 600,000 years

IPCC 2007


CO2 - 20,000 years

Methane

Temperature

CO2

Rate of Changeunprecedented for probably

millions of years!

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.”

Why is it not natural?

Climate has always been changing,naturally …


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


Changes Across Scales

Global-wide Glacier Collapse

20031900

Effect on Extreme Precipitation

Global Sea Level Rise


Viner (2002)

Models are now “Partners” to Data

Model Computation: - 15 minute time steps- 1 quadrillion calculations /yr

~150 km


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


Performance of CCSM-3

Surface Air TemperatureModel

Observations

El Niño-VariabilityModel

Observations

High Resolution Ocean Models



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


Simulations of the 20th century: Time

Meehl et al. 2004

Allforcings

Naturalonly



Future Climate ProjectionsNote: These are “What If” Scenarios, not predictions

IPCC, 2007

A2: 2020s

A2: 2090s


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!



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


Last Interglacial (~130 ka): +6m sea level



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



Paleo Analogs for future temperatures?Future climates might resemble the past >40 Mio yr ago



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


Future Sea Level and New Orleans (+1m)


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?


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)


CCSP 2.1a Mitigation Simulations


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?


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


The Great Challenge:Balancing Climate and Energy Needs

Thank you!



Paleocene-Eocene Thermal Maximum: A possible “analog” to study future impact on Earth System?

Zachos et al. 2005


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


Subtropical drying in with large scale warming?Can this fundamental concept be confirmed in past climates?


Documents

Golden, Mar 14, 2009WIPS – The Earth's Climate System1