Transcript Theoretical mechanism for natural radiative forcing of El Nino

Paleoclimate Reconstructions from HighResolution Proxy Data
Michael E. Mann
Department of Environmental Sciences, University of Virginia,
Charlottesville, VA
Collaborators: B. Adams, C. Ammann, R. Bradley, K. Briffa; M.
Cane; A. Clement, T. Delworth; M.K. Hughes, T. Osborn; P. Jones,
S. Rutherford; G. Schmidt; D. Shindell; S. Zebiak
Support: NOAA/NSF Earth Systems History program
Meeting on Tree Rings and Climate
Tucson, Arizona
April 6, 2004
Mann, M.E., Ammann, C., Bradley, R.S., Briffa, K., Crowley, T.J., Hughes, M.K., Jones, P.D.,
Oppenheimer, M., Osborn, T.J., Overpeck, J.T., Rutherford, S., Trenberth, K.E., Wigley, T.M.L., On Past
Temperatures and Anomalous late 20th Century Warmth, Eos, 84, 256-258, 2003 [MODIFIED:
Boreholes—Rutherford and Mann (in press); Crowley & Lowery (updated)]
Greater variability in
extratropics and
summer!
Mann, M.E., Ammann, C., Bradley, R.S., Briffa, K., Crowley, T.J., Hughes, M.K., Jones, P.D.,
Oppenheimer, M., Osborn, T.J., Overpeck, J.T., Rutherford, S., Trenberth, K.E., Wigley, T.M.L., On Past
Temperatures and Anomalous late 20th Century Warmth, Eos, 84, 256-258, 2003 [MODIFIED:
Boreholes—Rutherford and Mann (in press); Crowley & Lowery (updated)]
Annual Resolution Proxy Climate Indicators
INSTRUMENTAL
TEMPERATURE
RECORD
GLOBAL
PROXY
CLIMATE
RECORDS
Reconstructed Surface Temperatures
Mann, M.E., Bradley, R.S.,
Hughes, M.K., Global-Scale
Temperature Patterns and
Climate Forcing Over the
Past Six Centuries, Nature,
392, 779-787, 1998.
Sensitivity to target
region?
Comparison between Briffa
et al. NH extratropical warmseason NH mean
temperature reconstruction
with RegEM reconstruction
(a) unmasked
Rutherford, S., Mann, M.E., Osborn, T.J., Bradley, R.S., Briffa, K.R., Hughes, M.K., Jones,
P.D., Proxy-based Northern Hemisphere Surface Temperature Reconstructions:
Sensitivity to Methodology, Predictor network, Journal of Climate (in revision), 2004.
Sensitivity to target
region?
Comparison between Briffa
et al. NH extratropical warmseason NH mean
temperature reconstruction
with RegEM reconstruction
(a) unmasked
(b) masked
Rutherford, S., Mann, M.E., Osborn, T.J., Bradley, R.S., Briffa, K.R., Hughes, M.K., Jones,
P.D., Proxy-based Northern Hemisphere Surface Temperature Reconstructions:
Sensitivity to Methodology, Predictor network, Journal of Climate (in revision), 2004.
Sensitivity to target
region?
Comparison between Briffa
et al. NH extratropical warmseason NH mean
temperature reconstruction
with RegEM reconstruction
(a) unmasked
(b) masked
(c) based on Esper et al
(2002) locations only
Rutherford, S., Mann, M.E., Osborn, T.J., Bradley, R.S., Briffa, K.R., Hughes, M.K., Jones,
P.D., Proxy-based Northern Hemisphere Surface Temperature Reconstructions:
Sensitivity to Methodology, Predictor network, Journal of Climate (in revision), 2004.
Seasonal
Spatial
Patterns
Temperature Anomaly (oC)
Cold Season (multiproxy)
Warm Season (MXD)
Rutherford, S., Mann, M.E., Osborn, T.J., Bradley, R.S., Briffa, K.R., Hughes, M.K., Jones,
P.D., Proxy-based Northern Hemisphere Surface Temperature Reconstructions:
Sensitivity to Methodology, Predictor network, Journal of Climate (in revision), 2004.
Influence of Natural Radiative Forcing
Crowley, T.J., Causes of Climate Change Over the Past 1000
Years, Science, 289 270-277, 2000.
Volcanism
1000
1200
1400
1600
Solar
1800
2000
Jones, P.D., Mann, M.E., Climate
Over Past Millennia, Reviews of
Geophysics, in press, 2004.
European Winter Cooling During the Little Ice Age
Empirical
LIA winter cooling in
Europe associated with
an NAO trend due to solar
irradiance changes,
interacting w/
stratospheric
atmospheric dynamics
and chemistry
NASA/GISS Model
Shindell, D.T., Schmidt, G.A.,
Mann, M.E., Rind, D., Waple, A.,
Solar forcing of regional climate
change during the Maunder
Minimum, Science, 294, 21492152, 2001.
Annual average
late 17th vs late
18th Century
Temperature change
Proxy based
reconstruction
GCM Solar +
Volcanic patterns
Shindell, D.T., Schmidt, G.A.,
Miller, R., Mann, M.E., Volcanic
and Solar forcing of Climate
Change During the Pre-Industrial
era, Journal of Climate, 16, 40944107, 2003.
Volcanic Radiative Summer Cooling
Ensemble average summer (Jun-Aug) surface temperature
response following eruption of Pinatubo.
Shindell, D.T., Schmidt, G.A., Miller, R., Mann, M.E., Volcanic and Solar forcing of
Climate Change During the Pre-Industrial era, Journal of Climate, 16, 4094-4107, 2003.
Volcanic Winter Dynamical Warming
Ensemble average winter (Dec-Feb) surface temperature
response following eruption of Pinatubo.
Shindell, D.T., Schmidt, G.A., Miller, R., Mann, M.E., Volcanic and Solar forcing of
Climate Change During the Pre-Industrial era, Journal of Climate, 16, 4094-4107, 2003.
Mid-Latitude Summers
Greater variability?
Esper, J., Cook, E.R.,
Schweingruber, F.H., LowFrequency Signals in Long
Tree-Ring Chronologies for
Reconstructing Past
Temperature Variability,
Science, 295, 2250-2253,
2002.
Mid-Latitude Summers
Greater variability?
1000
1200
1400
1600
1800
2000
Volcanic Forcing of El Nino?
Adams, J.B., Mann, M.E., Ammann, C.M., Proxy evidence for an El Nino-like Response to
Volcanic Forcing, Nature, 426, 274-278, 2003.
Volcanic Forcing of El Nino?
Adams, J.B., Mann, M.E., Ammann, C.M., Proxy evidence for an El Nino-like Response to
Volcanic Forcing, Nature, 426, 274-278, 2003.
Solar Forcing of El Nino?
Decadally-smoothed Mann et al NINO3 (x-1)
Jones et al, Science, 2001
Verschuren et al, Nature, 403, 410-414, 2000.
Theoretical mechanism for natural
radiative forcing of El Nino
Cane, M.A., A.C. Clement, A. Kaplan, Y. Kushnir, D. Pozdnyakov,
R. Seager, S.E. Zebiak, and R. Murtugudde, Twentieth-Century
Sea Surface Temperature Trends, Science, 275, 957-960, 1997.
Theoretical mechanism for natural
radiative forcing of El Nino
Composite Nino3 (100 realizations of CZ model)
Tropical Volcanic radiative forcing (0.1 x W/m2)
Theoretical mechanism for natural
radiative forcing of El Nino
Mann, M.E., Cane,
M.A., Zebiak, S.E.,
Clement, A.,
Volcanic and Solar
Forcing of El Niño
Over the Past 1000
Years, submitted,
2004.
Response to Volcanic Forcing
Composite Nino3 (100 realizations of CZ model)
Tropical Volcanic radiative forcing (0.1 x W/m2)
Theoretical mechanism for natural
radiative forcing of El Nino
Mann, M.E., Cane, M.A.,
Zebiak, S.E., Clement, A.,
Volcanic and Solar Forcing of
El Niño Over the Past 1000
Years, submitted, 2004.
Superposed Epoch
Analysis AD 1649-1868
Superposed Epoch
Analysis AD 1000-1999
all (7) tropical events
exceeding -2 W/m2
All (7) tropical events
exceeding -4 W/m2
Tropical volcanic radiative forcing (0.1 x W/m2)
Theoretical mechanism for natural
radiative forcing of El Nino
Composite Nino3 (100 realizations of CZ model)
Tropical Solar radiative forcing (W/m2)
Tropical volcanic radiative forcing (0.1 x W/m2) 40 year smooth
Theoretical mechanism for natural
radiative forcing of El Nino
Response to Solar Forcing
Composite Nino3 (100 realizations of CZ model)
40 year smooth
Tropical Solar radiative
forcing (W/m2)
Mann, M.E., Cane, M.A., Zebiak, S.E., Clement, A., Volcanic and
Solar Forcing of El Niño Over the Past 1000 Years, submitted, 2004.
40 year smooth
Theoretical mechanism for natural
radiative forcing of El Nino
Cobb, K.M., C.D. Charles, R.L Edwards, H. Cheng, El NiñoSouthern Oscillation and tropical Pacific climate during the last
millennium, Nature, 424, 271-276, 2003.
Theoretical mechanism for natural
radiative forcing of El Nino
Combined response to Solar
+Volcanic Forcing
Ensemble mean
Nino3 (100
realizations of CZ
model)
40 year
smooth
Palymra coral
isotopes (standardized
to have same mean and
standard deviation as
Nino3 composite series)
Mann, M.E., Cane, M.A., Zebiak, S.E., Clement, A., Volcanic and Solar
Forcing of El Niño Over the Past 1000 Years, submitted, 2004.
CONCLUSIONS
•Differences between estimates of extratropical and full
(combined tropical and extratropical) hemispheric mean
temperature changes in past centuries appear consistent
with seasonal and spatially-specific responses to climate
forcing.
•Observations of an El Nino-like response to explosive
tropical volcanic eruptions are consistent with results
based on simulations with the Cane-Zebiak model
•Coral evidence of La Nina-like anomalies during the 12thearly 13th centuries, and El Nino-like anomalies during the
late 17th century, are reproduced by the simulated
response to total (solar+volcanic) natural radiative
forcing