Post on 20-Jan-2016
A paleoperspective on the
carbon cycle-climate systemFortunat Joos
Climate and Environmental Physics and Oeschger Centre of Climate Change Research
University of Bern
The The 1414C inventory inC inventory inthe Earth System: the Earth System:
a constraint on a constraint on 1414C productionC production
Production = - Decay of Production = - Decay of 1414CC = = 1414NNEarthEarth
Decay rate:Decay rate:=1/8267 yr=1/8267 yr1414C Inventory, C Inventory, 1414NNEarth Earth :mainly from data:mainly from data
Atmosphere 590 GtC 820 GtC
Vegetation/Soil 3000 to 4000 GtC
Marine Biota3 GtCOcean
38‘000 GtC
Sediments
Carbon Pools
Fossil5000 GtC
Dissolved Inorganic Carbon in the ocean varies between 1.9 and 2.5 mmol/kg
mol/kgSarmiento and Gruber, Ocean Biogeochemical Dynamics, 2006
Atmosphere 14C~ 0 %o
Vegetation/Soil 14C~ -15 %o
Ocean14C ~ - 152.2 %o
Reactive Sediments ( CaCO3, Organic)14C~ -200 %o
14C/12C in the Earth System
14 12 1314 / ( 25)
(1 2 ) 1 1000permil1000std
C C CC
R
Observed Deep Ocean 14C
Müller, et al., J. Climate, 2005
-50
-150
-250
permil
Simulated Deep Ocean 14C
in the Bern3D model
14C/12C-ratio varies in ocean within 0.96 to 0.76
An estimate:An estimate:
Observation-based:Observation-based: [10 [102626 atoms] atoms]Ocean: Ocean: 20,010 20,010 (85%)(85%)Atmosphere:Atmosphere: 360 360 (2%)(2%)
Model-supported:CaCO3 Sediment 350 Organic Carbon Sediment 170flux to litosphere · 920 (6%)
vegetation 360soils ~1,500 (8%)
Total Inventory 1414NNEarthEarth 23,670 10 23,670 1026 26 atomsatoms
(100%)(100%)
An estimate:An estimate:Total Inventory 1414NNEarthEarth 23,670 1023,670 1026 26 atomsatoms
Total Production: Total Production: 1414NNEarth Earth = 9.079 10= 9.079 1018 18 atoms satoms s-1-1
= 1.78 atoms cm= 1.78 atoms cm-2 -2 ss-1-1
Next steps: Next steps: • estimate transient effects estimate transient effects using the Bern3D modelusing the Bern3D model (atmospheric variation (atmospheric variation in in 1414C/C/1212C: 6%) and C: 6%) and link to solar modulationlink to solar modulation
• improve terrestrial estimate improve terrestrial estimate (peat and permafrost)(peat and permafrost)
How do past changes in How do past changes in radiative forcing compare withradiative forcing compare with
ongoing forcing changes?ongoing forcing changes?
Cause effect chain:Cause effect chain: Perturbation in radiative balancePerturbation in radiative balance
feedbacksfeedbacks
Climate ChangeClimate Change
Rates of ChangeRates of Change
CO
2 (p
pm
) Tem
per
atu
re
ano
mal
y (o
C)
180180
300300 -10-10
+4+4
TodayToday 800 ka BP800 ka BPAgeAge
Atmospheric CO2 and Antarctic temperature covaried over the past 800,000 years. CO2 acts as an amplifying feedback
(Lüthi et al., 2008)
(IPCC, 2007-500-500 00 100100Time kyrTime kyr
lati
tud
ela
titu
de
Summer insolation Summer insolation
Variations in Earth‘s orbit control seasonal and latitudinal distribution of solar insolation and likely caused glacial-interglacial cycles
60 W/m60 W/m22
-60 W/m-60 W/m22
Annual mean insolation Annual mean insolation
Time scales: 20,000 ++ years
10 W/m10 W/m22
(IPCC, 2007, Fig. 6.5)
Changes in greenhous gas concentration and ice sheet growth acted as amplifying feedbacks
Radiative Forcing at the Last Glacial Maximum Radiative Forcing at the Last Glacial Maximum
Orbital: large distributional effects, but small change in global annual mean insolation
Temperature response of the Bern model to orbital, greenhouse gas and ice sheet-albedo forcing
Glo
bal
Tem
per
atu
re
(oC
)
++1010
+16+16
TodayToday800 ka BP800 ka BP(Ritz et al., 2010)
Orbital only
Orbital + CO2 +ice
(IPCC, 2007, Fig. SPM-1a)
Time (years before present)Time (years before present)001000010000 50005000
300300
250250
350350
Car
bo
n D
ioxi
de
(pp
m)
Car
bo
n D
ioxi
de
(pp
m)
Rad
iati
ve F
orc
ing
(W
mR
adia
tive
Fo
rcin
g (
W m
-2-2))
00
11
Atmospheric CO2 is rising and far above the preindustrial range: CO2 from anthropogenic emissions causes warming and ocean acidification
Time scale of increase:decadal-to-century
Perturbation life time:millennial
Rates of climate change co-determine severity of impacts on socio-economic and natural systems
Rates of ChangeRates of Change
(Joos and Spahni, PNAS, 2008)
Potential Smoothingof peak in ice
Rates of change over the past 22,000 years inferred from splines through ice/atm. data
The rate of increase
in the combined
radiative forcing
from CO2, CH4 and
N2O during the
industrial era is very
likely to have been
unprecedented in
more than 10,000
years (IPCC, SPM,
2007)
How do rates of change in anthropogenic forcing compare with solar and volcanic forcing of the last millennium?
(Joos and Spahni, PNAS, 2008)
volcanoes
Solar (MM 0.25%)
sum of currentrates in anthropogenicforcings
Trend in solar irradianceover satellite period:10-6 W m-2 yr-1
Rates of decadal-scale change: Natural (solar, volcanoes) versus human made
Last millennium:Last millennium:Are suggestions of a small Are suggestions of a small
influence of solar changes on influence of solar changes on climate overclimate over
the past millennium plausible?the past millennium plausible?
A carbon cycle-climate perspectiveA carbon cycle-climate perspective
Data-based reconstructionsData-based reconstructions
Muscheler et al., 2005
Today‘s solar activity is not unusual in the contextof the last millennium: solar modulation from 14C tree ring record and carbon model
1600 AD
Different solar forcing reconstructions from10Be,14C, sunspot records differ in amplitude (not in evolution)
1000 2000200015001500
(IPCC, 2007, Fig. 6.14)
YearYear
Volcanic, solar and other forcingsVolcanic, solar and other forcings
Bard et al., 2000 (MM: -0.25%)
Wang et al., 2005(MM -0.08%)
800 2000200012001200 16001600
(IPCC, 2007, Fig. TS-20)
Northern Hemisphere temperature reconstructionsNorthern Hemisphere temperature reconstructions
YearYear
Te
mp
era
ture
an
om
aly
(T
em
pe
ratu
re a
no
mal
y (
ooC
)C
) Reconstructed ranges for low frequencyvariations in NH temperature are between ~ 0.3oC and 1oC
Siegenthaler et al., 2004
(Etheridge al.)(Neftel al.)
Preindustrial CO2 variations: an additional constraint
Climate model resultsClimate model results
WithWith
WithoutWithout
Anthropogenic Anthropogenic ForcingForcing
(IPCC, 2007, Fig. 6.14)
1000 14001400 18001800YearYear
Te
mp
era
ture
an
om
aly
(T
em
pe
ratu
re a
no
mal
y (
ooC
)C
) Climate models forced with prescribed forcing (low and high solar): simulated versus reconstructed NH temperature
1600 AD
Anthropogenic Anthropogenic ForcingForcing
(IPCC, 2007, Fig. 6.14)
Simulated temperatures with and without anthropogenic Simulated temperatures with and without anthropogenic forcing and with weak or strong solar irradiance variationsforcing and with weak or strong solar irradiance variations
1000 14001400 18001800YearYear
Te
mp
era
ture
an
om
aly
(T
em
pe
ratu
re a
no
mal
y (
ooC
)C
) A significant fraction of the reconstructed NH interdecadal
temperature variability over at least the seven centuries prior to
1950 is very likely attributable to volcanic eruptions and changes in
solar irradiance
Modelled versus measured COModelled versus measured CO22
Simulated atmospheric CO2
versus ice core data
Model results: smoothed with DML age distribution
Simulated versus ice core CO2
Probabilistic estimates of the Probabilistic estimates of the sensitivity of COsensitivity of CO22 to temperature to temperature
from reconstructionsfrom reconstructions
COCO22//T (ppm/K)T (ppm/K)
A probabilistic assessment of the CO2-temperature sensitivity based on different temperature and CO2 reconstructions
0 20 40 60
Pro
bab
ilit
y
(Frank et al., 2010)
Sensitivity (ppm per oC)
Comparison of data-based Comparison of data-based estimates of the sensitivity of COestimates of the sensitivity of CO22
to temperature with model resultsto temperature with model results
0 20 40
Pro
bab
ilit
y
(Frank et al.,2010)Sensitivity (ppm per oC)(Range of median values)
Reconstructed
20th century C4MIP models
• The amplitudes of the preindustrial decadal-scale
Northern Hemisphere temperature changes from the
proxy-based reconstructions (<1oC) are broadly
consistent with the ice core CO2 record and our
quantitative understanding of the carbon cycle and
reconstructions of solar and volcanic forcing
• The small changes in CO2, CH4, and N2O over the
last millennium also suggest a limited range of
climate variability over this period
• A small solar influence on climate, despite large
variations in solar modulation, is consistent with the
climatic records of the last millennium
Thank you for your attention!
Surface temperature anomaly after a collapse of the North Atlantic Circulation
The power spectrum of the 14C and 10Be solar modulation records shows common peaks
Wanner et al., 2009
Low solar forcing: Simulated atmospheric CO2 versus ice core data
Model results: smoothed with DML age distribution
Large low frequency temperature variations are not compatible with the ice core CO2 record
High Solar Forcing
Natural forcings: contribution to 20th century warming is less than 0.15 K for all solar scalings