ATMOS 397G
Biogeochemical Cycles and Global Change
Lecture #7
Integrated Assessment of
Climate and Carbon Cycle
Atul K. Jain
Department of Atmospheric Sciences
University of Illinois, Urbana, IL
email: jain@atmos.uiuc.edu
How Much is a % Contribution
of CO2 in the Atmosphere
 25%
 10%
 5%
 1% or less
Why Model The Carbon Cycle
• Increasing atmospheric CO2 content may
significantly alter Earth's climate and
biosphere in the next century
• To predict climate and its impacts, we
need to be able to predict future CO2
concentrations
CO2 is the Single Most Important GHG
Observed Atmospheric CO2 Concentration
(1000-2000)
1000
1200
1400
1600
1800
2000
18
50
18
60
18
70
18
80
18
90
19
00
19
10
19
20
19
30
19
40
19
50
19
60
19
70
19
80
19
90
20
00
CO2 Emission Rates (GtC/yr)
Human Activities Perturb Natural
Carbon Cycle
12
10
Land Use
Series2
8
Series1
Fossil Fuel
6
4
2
0
Year
Carbon Cycle Modeling
The ability to predict the response of the carbon
cycle to anthropogenic emissions relies on the:
Understanding of Carbon Cycle Mechanisms
Ocean transport and chemistry, and, air/sea exchange
plant physiology and soil processes
 CO2 & Nitrogen Fertilization
Forest regrowth
Response to climate change
Measured behavior of the past carbon cycle
CO2 Fossil Fuel and Cement emissions
Observed CO2 concentration
Observed distribution of carbon isotopes (12C, 13C, 14C)
Industrial Society & the Global Carbon Cycle
Units: Gt C and Gt C y-1
Atmosphere
…are leading to a
build up of CO2
in the atmosphere.
3.2
750
63
3
500 Plants
60
Soil
2000
…and land clearing
in the tropics...
6.3
About
16,000
1.6
Fossil emissions ...
91.7
90
1.7
Surface
Ocean
IPCC (2001)
Fossil Deposits
Intermediate
& Deep
Ocean
1,000
38,000
Model Validation
0
Ocean Depth (meter)
Ocean Depth (meter)
Atmospheric ²
14C (‰)
0
(a)
0
1000
-20
1000
2000
-40
-60
3000
3000
Modeled
Observed
4000
4000
2-250
13C
-6.5
-7
-8
1750
Modeled
Observed
1800
0
Modeled
Observed
Observed
2.1
2.350
-175
-100 2.2 -25
14
² CCO
Total Inorganic
(‰)
2(mol/m 3 )
2.4
125
Evidence in the Atmosphere and Ocean Points to Link Between
Human-Related Emissions and CO2 Rise
Ocean Depth (meter)
Atmospheric  13C (‰)
-80
1840 1865 1890 1915 1940 1965 1990
Year
-6
-7.5
Modeled
2000
1850 1900
Year
1950
2000
(b)
1000
2000
Modeled
3000
4000
-0.5
0
Jain et al. (1996)
Observed
0.5
1
13 C (‰)
1.5
2
2.
Global CO2 Budget (GtC/yr)
Based on Atmospheric CO2 and O2 Data
1990s
1980s
1.6 ± 0.8
6.3 ± 0.6
3.2 ± 0.2
1.7 ± 0.5
3 ± ???
• The global CO2 budget is usually defined as the mass balance among
sources and sinks of CO2 produced by human activities.
• Balancing the global CO2 budget requires a large unidentified (“missing”)
carbon sink on land.
(The transfers shown (in metric tones of carbon per year) represent the CO2 budget
for the 1980’s and 1990’s as estimated by the IPCC (1996 and 2001).
Natural Transfers Fluctuate over
Short Time Scale
8
CO2 GROWTH RATE
6
Global
(NOAA)
Rate of increase of CO2
Fossil Fuel
Cape Grim
(CSIRO)
4
2
Mauna Loa
(Scripps/NOAA)
30
Pinatubo
La Nina
0
-30
El Nino
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
(R J Francey, pers. Com)
• Assessment of the Global CO2 Budget Requires Long
Term Measurements and Models
ISAM Estimated CO2
Concentrations for IS92a Scenario
Concentration (ppmv)
850
800
750
700
650
600
Reference-With Climate
Feedback
Low-With Climate Feedback
High-With Climate Feedback
Reference-Without Climate
Feedback
550
500
450
400
350
1990
2010
2030
2050
Year
2070
2090
GREENHOUSE GAS
EMISSIONS SCENARIOS
•
Purposes:
 to
develop an understanding of how
human-related emissions will affect future
climate
 to
enable us to look ahead & evaluate
potential impacts for the range of possible
future changes in climate
 to
be able to accurately compare present
GHG emission reduction costs with future
damages
Future Projections
Major Uncertainties
• Socioeconomic (Future Emissions
SRES Scenarios)
• Carbon Cycle (Resulting CO2
Concentration) and
• Climate Sensitivity (ºC for 2CO2)
Based on ISAM
Impact of Stabilizing Emissions versus
Stabilization Concentrations of CO2
The Challenge of Stabilization of Atmospheric
Concentrations of Carbon Dioxide
• Emissions of CO2 due to
fossil fuel burning will be the
dominant influence on
atmospheric CO2 in the 21st
century
• Stabilization of CO2 at twice
the pre-industrial level will
require emissions to drop to
below 1990 levels in less
than 50 years.
• Emissions will need to
continue to decrease steadily
thereafter to a very small
fraction of current emissions.
IPCC (2001, Based on ISAM)
Cumulative Carbon Emission Ranges for
WRE Scenarios (2100)
Cumulative CO2 Emissions (GtC)
1800
1600
1400
1200
1000
800
WRE Range of
600 Cumulative
Emission
400
200
0
SRES
Range
WRE450
WRE550
WRE650
WRE750 WRE 1000
A Grand Challenge:
Study Feedbacks Throughout The Earth
In the science andSystem
policy world …
EMISSIONS
CONCENTRATIONS
Socio-economic +
energy analyses
and modeling
Carbon Cycle &
Chemical transport
models
IMPACTS
CLIMATE CHANGE
RADIATIVE
FORCING
A-O-CIRCULATION
Radiative
transfer
models
A-O Models
Integrated Assessment
Tying it all together:
The Concept of Integrated Assessment Modeling (IAM)

Purpose:
 to interface science with policy
 to
provide information of use to
decision-makers, not just for the
sake of increasing knowledge for
knowledge’s sake alone
 to
provide insights that cannot be
easily derived from individual
component models
Modeling the Earth-Climate
System: Components
Human Activities
Biogeochemical
Cycles
Biosphere
Climate
Processes
Atmospheric
Chemistry
Gases, aerosols
•Temperature
•Winds
•Clouds, Precip.
Ocean Processes
Integrated Assessment Modeling
• “Integrated” refers to:
 the completeness of causal links cycle coverage
 the inclusion of feedback loops within and between
cause-effect chains
 the bringing together of information & analysis from
disparate disciplines
• “Assessment” refers to:
 the focus of the models on evaluation and
assessment of human & natural contributions and
responses to climate change
What would the ideal IAM look like?
•
It would:
model the complete causal chain,
including all feedbacks
 have an interface that could be used
interactively by a reasonably
educated policy-maker on their own
desktop PC
 have results that don’t differ
significantly from a hypothetical IAM
made of the most comprehensive
models available

The Integrated Science
Assessment Model (ISAM)
• ISAM is:
a deterministic projection, policy evaluation
model
capable of evaluating climatic impacts of one
policy decision at a time
a process-oriented model
has a modular structure with sub-models being
simplified versions of models from different
scientific disciplines, with standardized
assumptions
Integrated Science Assessment Model (ISAM)
Earth System Model of Intermediate Complexity
BIOSPHERE
Agricultural Land Use Model
EMISSIONS
PNNL MiniCam Model
GHG emissions from
industrial & energy-related
sources
CHEMICAL TRANSPORT
2D Atmospheric Chemical
Transport Box Model
Concentrations of GHG,aerosols
and
other radiatively active species
CO2 fluxes from land use
change
CARBON CYCLE
2D Coupled AtmosphereOcean-Biosphere Model
Carbon dioxide concentrations
CLIMATE MODEL
2D Radiative Transfer Model
2D Atmosphere-Ocean-Land Moisture & Energy Balance Model
Changes in global temperature,
precipitation and sea level
IMPACT ASSESSMENT STUDIES
Integrated Science Assessment Model (ISAM)
as Tool for Scientific and Policy Analysis
• Use all key Climate System Components and
Feedbacks at an appropriate level of detail;
• Account sub-grid climate processes by using empirical
relationships to approximate net effects;
• Approximate the effects of various physical and
chemical processes based on AOGCM and CTM
• Design to Upgrade as knowledge improves;
• Evaluate Chemical and Climate Feedback Effects on
Policy Developments;
• Treat Uncertainty as an Essential Feature;
• Global in scope, but resolve regional distribution.
GOAL - ISAM
The development of an ideal tool
based on solid science
to increase our understanding
of earth system feedbacks
and to address multi-dimensional
science and policy issues related to
climate change.
Global-Annual Mean Version of Integrated
Science Assessment Model (ISAM)
ISAM WWW INTERFACE
http://isam.atmos.uiuc.edu/isam
• Purpose:
To make a state-of-the-art integrated
assessment model available to the
general public in a user-friendly
format
ISAM Interface - Objectives
• To give students/Educators/Policy Makers a tool for:
 understanding the science of global change
• using ISAM students see how physical processes and
parameters in the climate system determine its
behavior
 understanding the long-term consequences of near-term
policy choices
• model outputs show long residence times of greenhouse
gases in the atmosphere
 understanding how policy makers assess the implications of
their decisions
• students use a model identical to that used by policy
makers in forming greenhouse gas emissions policies
WWW INTERFACE OF ISAM
(http://isam.atmos.uiuc.edu/isam)
• This Interface Enables the User to
 Run the ISAM on the Web Using an Intuitive Menu
System
 Alter the Various Physical Formulations of ISAM
 Construct Scenarios of Greenhouse Gas and aerosol
emissions
 Assess their Impact on the Global Climate and on Sea
Level
Results are Presented as Graphs and Tables
Users of Our Web Site
• Students of climate, and climate change, investigating
the past and future effects of anthropogenic climate
forcings.
• Students of public policy studying the implications of
proposed greenhouse-gas mitigation strategies.
• Educators preparing course material on the science of
global climate change and the implications of
greenhouse-gas mitigation strategies.
• Policy makers, in both government and the private
sector, seeking projections of how their decisions will
affect future greenhouse-gas concentrations and
climate change.
Model Inputs
• Step 1: Model Formulation for the Steady State:
 Use default model settings or alter parameter values
Question to answer: What are the implications of different
values for climate sensitivity?
• Step 2: Model Calculations of the Greenhouse Effect
from Pre-Industrial Times into the Future
 Run the model based on the Historical Observed Data, 17651990
Question to answer: How well does the model reproduce past
climate change? How does this depend on model parameters?
 Prescribe the Future Emission Scenario for Dates after 1990
a) Select IPCC (Intergovernmental Panel on Climate Change)
Scenarios for 1990-2100... OR... Specify emissions of major
greenhouse gases (CO2, CH4, N2O, CFCs, SO2) in key years.
(b) Select end year of calculation (> 1995)
Model Output
• Results Available as Graphs and Tables include:
 Temperature Change and Rate of Temperature
Change
 Sea Level Change and Rate of Sea Level Change
 Historical CO2 Emissions, Fluxes, and Atmospheric
Concentrations
 Future Emissions of Major Greenhouse Gases (CO2,
CH4, CO, OH, N2O, CFCs, and SO2)
 Concentrations of Major Greenhouse Gases
 Total Tropospheric Chlorine and Ozone Changes
 Radiative Forcings for Major Greenhouse Gases and
Aerosols
THE END