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A Decline in the Northern A Decline in the Northern Hemisphere COHemisphere CO22 Sink Sink
from 1992 - 2003from 1992 - 2003
John MillerJohn Miller11, Pieter Tans, Pieter Tans11, Jim , Jim WhiteWhite22, Ken Masarie, Ken Masarie11, Tom , Tom
ConwayConway11, Bruce Vaughn, Bruce Vaughn22, Jim , Jim RandersonRanderson33, Neil Suits, Neil Suits44
1. NOAA/CMDL, Boulder2. INSTAAR, University of Colorado, Boulder3. U. of California, Irvine4. Colorado State University, Fort Collins
OutlineOutline
1.1. Trends in NH COTrends in NH CO22 data indicate a data indicate a change in the sink.change in the sink.
2.2. Two reasons why change originates Two reasons why change originates in the terrestrial biosphere.in the terrestrial biosphere.
3.3. What might be causing the change?What might be causing the change?
Conceptual ModelConceptual Model
FF
Rectifier Sink
COCO22 = CO = CO22 Site – CO Site – CO22 SPO = SPO =Fossil Fuel + Sink (+ rectifier)Fossil Fuel + Sink (+ rectifier)
Meridional COMeridional CO22 Gradient Gradient
19981992
2003
Gradient increasing; big jump from 1998-2003
MBLContinentalHi-Altitude
Fits to MBL
Sites used in studySites used in study
Determining trends at a siteDetermining trends at a site
SPO
ICE
CO
2 (p
pm
)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
bal
tap
uum
bme
bmw
gmi
key
kum
mhd mid
shm al
t
brw
ice
stm
zep
Site Code
Sit
e-S
PO
tre
nd
(p
pm
/yr)
Boreal marineTemperate marineContinental
Distribution of Trends: 1992-2003Distribution of Trends: 1992-2003
Expected trend from FF
•14/16 sites increase faster than expected: p < 0.01•Excluding 1992 and/or 2003 p < 0.05
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
ask ba
lb
sch
un
kzd
kzm lef
tap
uta
uu
mw
isw
lga
zrb
me
bm
wg
mi
key
kum
mh
dm
idsh
m alt
brw ice
stm
zep
Site code
Sit
e-S
PO
tre
nd
(p
pm
/yr)
Boreal marineTemperate marineContinental
Distribution of Trends: 1997-2003Distribution of Trends: 1997-2003
Expected trend from FF
Continental – Marine trend differences indicate a terrestrial origin.
Could continental Could continental trendtrend signal be Fossil? signal be Fossil?
-5
-4
-3
-2
-1
0
1
2
3
ask bal bsc hun kzd kzm lef tap uta uum wis wlg
site code
sit
e-M
BL
tre
nd
[p
pb
CO
/yr]
1.7 ppb/yr
MBL
Site
•Given a CO/CO2 emissions ratio of 10 ppb/ppm max. fossil fuel contribution of 0.2 ppm/yr.
What about changes in N/S transport ? What about changes in N/S transport ?
North/South SFNorth/South SF66 differences from 1997-2003 differences from 1997-2003 indicate a trend in inter-hemispheric exchange.indicate a trend in inter-hemispheric exchange.
Decreasing IHE implies less fossil emissions Decreasing IHE implies less fossil emissions stored in the NH.stored in the NH.
Thus, even larger sink changes are required to Thus, even larger sink changes are required to explain the observed gradient, 1997-2003.explain the observed gradient, 1997-2003.
11.1
1.21.3
1.41.5
1.61.7
1996 1998 2000 2002 2004
Inte
r-h
emis
ph
eric
exc
han
ge
tim
e [y
r]
Use 2D model to quantify sink Use 2D model to quantify sink changes.changes.
1.1. A 2D model of atmospheric transport to A 2D model of atmospheric transport to quantify the flux changes, andquantify the flux changes, and
2.2. Measurements of Measurements of 1313C/C/1212C in COC in CO22 ( (1313C) to help C) to help determine the origin.determine the origin.1313C is a tracer for terrestrial fluxes.C is a tracer for terrestrial fluxes.
CO213C
Ocean
Land
Total
18 – 53 N
Mid-latitudeMid-latitude non-fossil non-fossil Carbon Fluxes Carbon Fluxes
=1.5 Pg (1015g) C
• Changes in the terrestrial biosphere appear to drive the trend.•Biosphere trend is relatively insensitive to C3/C4 and other parameters.
p<0.01p<0.06
Correlation of Flux and Climate Correlation of Flux and Climate AnomaliesAnomalies
Zonally Averaged Climate
r =-0.7r = 0.3
Correlation of Flux and Climate Correlation of Flux and Climate AnomaliesAnomalies
Eurasian Average Climate
r =-0.4
Correlation of Flux and Climate Correlation of Flux and Climate AnomaliesAnomalies
North American Average Climate
r =-0.7
ConclusionsConclusions
1.1. NH carbon sink shrunk from 1992 – NH carbon sink shrunk from 1992 – 2003 by ~1.5 billion tons of C; 2003 by ~1.5 billion tons of C; probably driven by land.probably driven by land.
2.2. Regardless of whether this persists, Regardless of whether this persists, it demonstrates that surface uptake it demonstrates that surface uptake can change rapidly.can change rapidly.
3.3. Analysis of climate anomalies Analysis of climate anomalies hintshints at drought as a driver of variability at drought as a driver of variability in temperate NH.in temperate NH.