EBMs and EMICs
Andrey Ganopolski
Potsdam Institute for Climate Impact Research
• what are EBMs and EMICs?
• do we still need simple climate models?
• do you need to know something about these models?
SIMPLE
INTERMEDIATE
COMPLEX
Earth’s Global Energy Budget
„Classification“ of climate/Earth system models
Simple:
EBMs
EBM (Energy Balance Models)
Intermediate: EMICs
EMIC (Earth system Models of
Intermediate Complexity)
Complex:
GCMs (General Circulation Models)
Incoming Solar - Reflected
= Outgoing Longwave Radiation
Global Energy Balance Model (EBM)
RI
4 r 2  T
4
  r 2 S 0 (1   p )
S0=1360 W/m2; p
TBB = 255K = -18oC
Tobs= 287K=15oC
T=33oC – greenhouse effect
Sensitivity of global EBM
R  F (Radiative Forcing)

dT
 4 T
dR

3 1
 0 . 26
K
Wm  2
F2xCO2=4 W/m2 → CS=1oC
Modified Global EBM
m  Ts
4
S0

(1   p )
4
m=0.64

dT
3
 4 mTs
dR

1
K
 0.3
Wm  2
m=m(Ts) (Sellers, 1968)
Budyko’s type EBM
S0
A  BT s 
(1   p )
4
B ≈ 2 W/(m2K)
dT
K
 0 .5
dR
Wm  2
→ CS ≈ 2oC
Zonally averaged (1-D) Budyko-Sellers EBM
T=T()
0  I  R   2 FT
Budyko-North EBM
dT
d
(1  x 2 ) s
dx
dx
0.3, Ts  15 0C
p  
0


T
C
0
.
6
,
15
s

0  S ( x)(1   p )  A  BT  D
x=sin()
A, B, D - constants
EBM assumptions
• No distinction between ocean and land
• Planetary albedo depends only on the surface
temperature
• Outgoing longwave radiation depends only on
the surface air temperature
• Combined atmospheric sensible, latent and
oceanic heat fluxes ~ surface temperature
gradient
Earth’s Global Energy Budget
2-D seasonal EBM
T=T(,t)
T
C  S ( , t )(1   p (T ))  A  BT  D 2T
t
Amplitude of annual temperature cycle
model
observations
Earth climate hysteresis („snowball Earth“)
sin(latitude)
Poles
Equator
Solar constant
2-D Energy Moisture Balance Model
T=T(,t), Q=Q(,t),
T
C  S ( , t )(1   p (T ))  A  BT  DT  2T  L( P  E )
t
Q
c  DQ  2Q  E  P
t
Improvement ???
Sellers (1969)
Atmosphere
sensible
Atmosphere
latent
Ocean
Total
atmosphere-ocean
intermediate complexity + climate model
h-index: 44
Why we „invented“ EMICs?
1970th
CLIMBER-2
1980th
1990th
2000th
atmosphere
now
upper ocean
deep ocean
ice sheets
carbon cycle
glacial cycles
0.1
1
10
100
1000
time
scales
(yrs)
10,000 100,000 1000,000
EMICs Zoo
EMBM
(2D)
ADSM
(2.5D)
Q-G AGCM
(3D)
ATMOSPHERE
CLIMBER-2: ADSM + ZAOM
CLIMBER-3: ADSM + OGCM
UVic:
EMBM + OGCM
GENIE-1: EMBM + Q-G OGCM
LOVECLIM: Q-G AGCM + OGCM
OCEAN
ZAOM
(2.5D)
QG-OGCM
(3D)
OGCM
(3D)
CLIMBER-2.3 structure
Universal vertical structure in CLIMBER-2
Universal meridional, zonal mean structure in CLIMBER-2
Zonally averaged atmospheric characteristics
Simulation of the last 800 Kyr
Orbital forcing
(W/m2)
GHGs radiative
forcing
(W/m2)
D
(Antarctic
Temperature)
(%o)
18O
(ice volume)
(%o)
Paleodata/model
Forcings (input)
(orbital forcing + GHGs)
Simulations of the last 400 Kyr
orbital forcing + GHGs
yrs. BP
© CLIMBER
1. Global cooling of 6oC, tropical cooling ~ 2oC
2. Weakening and shoaling of the Atlantic
meridional overturning circulation
3. Strong impact of changes in the oceanic
heat transport on regional and global
temperatures
1. Global cooling of 6oC, tropical cooling ~ 2oC
2. Weakening and shoaling of the Atlantic
meridional overturning circulation
3. Strong impact of changes in the oceanic
heat transport on regional and global
temperatures
Brandefelt & Otto-Bliesner (2009)
1. Large (up to 3oC) summer warming over
the NH continents
2. Amplification of high latitude warming due to
the vegetation feedback
3. Strong vegetation-precipitation feedback in
subtropics
1. Large (up to 3oC) summer warming over
the NH continents
AO
AOV
2.00
mm/day
1.60
2. Amplification of high latitude warming due to
the vegetation feedback
3. Strong vegetation-precipitation feedback in
subtropics
1.20
0.80
0.40
0.00
0.00
Braconnot et al. (2007)
1. Large (up to 3oC) summer warming over
the NH continents
2. Amplification of high latitude warming due to
the vegetation feedback
3. Strong vegetation-precipitation feedback in
subtropics
CLIMBER2
IPSL
ECHAM-5
4. Strong synergy between vegetation and
oceanic feedbacks
TOV >> TO+TV
Conclusions
Simple (intermediate) models are useful as exploratory tools
They facilitate understanding and good for teaching
BUT they have serious limitations and have to be used with
great caution!