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The Climate/Human Interface
Tim Killeen
Director
National Center for Atmospheric Research
The Santa Fe Institute
May 8, 2004
"Why does applied science bring us so little happiness? The simple answer is
that we have not yet learned to make proper use of it. In time of war it has given
men the means to poison and mutilate one another. In time of peace it has made
our lives hurried and uncertain. It has enslaved us to machines. The chief
objective of all technological effort must be concern for mankind. Never forget
this when you are pondering over your diagrams and equations!"
Einstein to Students, 1931.
Key finding of the Intergovernmental Panel on
Climate Change: Humans are affecting Earth’s
climate
“The balance of evidence suggests a
discernible human influence on global
climate”
“There is new and stronger evidence that
most of the warming observed over the last
50 years is attributable to human activities”
CAUSES OF CLIMATE CHANGE
HUMAN (‘ANTHROPOGENIC’) FACTORS
Greenhouse gases (CO2, CH4, etc.)
Sulfur dioxide and other aerosol precursors
NATURAL FACTORS
External forcing (solar, volcanoes, etc.)
Internally-generated variability
Climate Reconstructions : Past Millennium
- millennial climate trend
- centennial and multi-decadal variability: External Drivers?
Medieval Warmperiod
Recent Warming
Little Ice Age
Mann et al. 2003
Community Climate System Model
CCSM June, 2003 Workshop in Breckenridge:
>350 participants, >30 universities, >50 institutions
2006
2005
2004
2003
2002
2000
1996
1993
The Community Climate System Model: Past, Present and Future
Development on CSM Begins
First Coupled Simulation: No Flux Corrections Needed
Formation of Working Groups
CSM Special Issue
Ocean Model
Land Model
CSM changes to Community Property
Released to Community
Interactive Aerosols
Coupled Carbon/Nitrogen
Coupled Chemistry
Glacial Model
IPCC AR4
20th Century Experiments
Forcings: Combined Natural-Anthropogenic and Natural only
Simulation of Recent Climate
Community Climate System Model
Paleoclimate Version
A significant first for the CCSM –
realistic simulation of the El
Niño/Southern Oscillation. The figure
shows Dec-Jan-Feb anomalies of
precipitation (mm/day), sea level
pressure (mb), sea surface temp (C)
and ocean temp (C) for a composite of
13 El Niño events in the CCSM.
Support
CRIEPI/NCAR/LANL/Kyushu
Consortium
supported by
Kyosei Project
“Sustainable Coexistence of
Humans, Nature and the Earth”
Ministry of Education, Culture, Sports,
Science and Technology of the
Uncertainty in Emissions
SRES DECADAL FOSSIL-FUEL CO2 EMISSIONS
40
35
A1 - RED
B1 - BLACK
A2 - GREEN
B2 - BLUE
FOSSIL CO2 EMISSIONS (GtC/yr)
MEAN - MAGENTA
30
25
20
15
10
5
0
1990
2000
2010
2020
2030
2040
2050
YEAR
2060
2070
2080
2090
2100
PDF FOR CO2 CONCENTRATION IN 2100 : SRES SCENARIOS
0.0025
5%
95%
50%
PROBABILITY DENSITY (ppm**-1)
0.002
0.0015
0.001
0.0005
0
300
400
500
600
700
800
900
1000 1100 1200 1300 1400 1500
CO2 CONCENTRATION (ppm)
PROBABILISTIC PROJECTIONS OF
FUTURE GLOBAL-MEAN WARMING
(from Wigley & Raper, Science 293, 451-454, 2001)
UNCERTAINTIES ACCOUNTED FOR:
(1) Emissions
(2) Climate Sensitivity
(3) Aerosol forcing
(4) Ocean mixing rate
(5) Carbon cycle
1.8
PROBABILISTIC PROJECTIONS OF GLOBAL
WARMING
1990-2030
1.4
o
-1
PROBABILITY DENSITY (( C) )
1.6
1.2
1
0.8
1990-2070
0.6
0.4
1990-2100
0.2
0
TAR RANGE
0
1
2
3
4
5
6
o
7
GLOBAL-MEAN TEMPERATURE CHANGE FROM 1990 ( C)
Modeling the Entire EarthClimate system
Human
Activities
Biogeochemical
Cycles
Biosphere
Climate
Processes
Atmospheric
Chemistry
Gases, aerosols
•Temperature
•Winds
•Clouds, Precipitation
Ocean Processes
• Computational resources approaching the ability to model
the entire Earth system
• Many individual processes still uncertain
Minutes-To-Hours
Components Of Terrestrial Biogeoscience
Chemistry
Temperature, Precipitation,
Radiation, Humidity, Wind
CO2, CH4, N2O
ozone, aerosols
CO2 CH4
N2O VOCs
Dust
Heat
Moisture
Momentum
Biogeochemistry
Aerodynamics
Water
Energy
Biogeophysics
Carbon Assimilation
Decomposition
Mineralization
Microclimate
Canopy Physiology
Days-To-Weeks
Years-To-Centuries
Climate
Phenology
Intercepted
Water
Snow
Soil
Water
Hydrology
Leaf Senescence
Species Composition
Ecosystem Structure
Nutrient Availability
Water
Evaporation
Transpiration
Snow Melt
Infiltration
Runoff
Gordon Bonan
Bud Break
Gross Primary
Production
Plant Respiration
Microbial Respiration
Nutrient Availability
Watersheds
Ecosystems
Surface Water
Subsurface Water
Geomorphology
Hydrologic
Cycle
Species Composition
Ecosystem Structure
Vegetation
Dynamics
Disturbance
Fires
Hurricanes
Ice Storms
Windthrows
Earth System Modeling
Preliminary focus on carbon and nitrogen cycle modeling
across spatial scales, and interactions of these cycles with
the climate system.
The Global C Cycle
The Global N Cycle
Atmospheric
CO2
Atmospheric
N species
Legend
Vegetation
Biomass
C flux
N flux
Temp
sensitivity
Soil
Organic
Matter
Coupled Carbon-Nitrogen dynamics
• Strong feedback between decomposition and plant growth:
soil mineral N is the primary source of N for plant growth.
• Can result in a shift from C source to C sink under warming.
Carbon Sink/Source response to +1° C step change
sink
(temperate deciduous broadleaf forest)
Coupled C-N model
C-only model
Thornton, in prep.
Simulated Leaf Area Index for Evergreen Needleleaf Forest, NW U.S.
Peter Thornton: 70 hours threaded code
CCSM Climate “Forecasts”
Produced by Gary Strand, NCAR
Cosquer
Cave
18,000-27,000 years ago
Dramatic proof of profound
climate change, sea level
change - and human
adaptation
Our Generation
Some Interdisciplinary
Opportunities and Thoughts
Earth Systems – Observing and Modeling
Regional Modeling of the Future
Decision Tools
Understanding Abrupt Climate Change
Beyond Kyoto and IPCC: A 2050 Project?
Some New NCAR Scientists I
Unused slides follow
Three Interleaved Grand
Challenges
"Getting to" the needed
Coupled models of the
Earth System (GEO)
"Finding out how to get
there" (Computer Science
and ITR)
"Training the workforce" to
enable appropriate
expertise and responses
(EHR, GEO, CISE, etc.)
Extreme droughts are the ‘norm’
Palmer Drought Severity Index
GYE PDSI reconstruction
8
20 yr moving average
20th C average
4
0
-4
Lisa Graumlich
-8
1100 1200 1300 1400 1500 1600 1700 1800 1900 2000
CCSM Time Line
for IPCC
Comparison CSM with different
Paleoclimate Reconstructions:
Only clear difference is to Mann et
al. (1999), which is warmer ~1450-1720
Jones et al. (1998): is mostly summer season.
Difference: < 0.1 C
Crowley & Lowery (1999): Only 11-year
average. Difference: very small
Briffa et al. (2001): exclusively tree-rings, but
with low-freq. retention:
somewhat warmer 1400-1500.
Huang et al. 2000: Subsurface (borehole) temperatures: ~1 C:
Estimates of Total Anthropogenic Forcing
Kiehl et al., JGR 2000
Aerosol Forcing during INDOEX
Collins et al., JGR submitted
Pinatubo
unknown
Kuwae
Huaynaputina
Parker
Tambora
unknown
Krakatau