Transcript Shindell, DT, Schmidt, GA, Miller, R., Mann, ME, Volcanic and Solar

Climate Changes Over the Past
Millennium: Relationships with
Mediterranean Climates
Michael E. Mann
Department of Environmental Sciences, University
of Virginia, Charlottesville, VA
Historical Reconstruction of Climate Variability and Change
in Mediterranean Regions
Bologna, Italy
Oct. 5, 2004
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.
Reconstructed Surface Temperatures
Climate Change 2001: The
Scientific Basis, Houghton, J.T.,
et al. (eds.), Cambridge Univ.
Press, Cambridge, 2001
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 (2004); Crowley & Lowery (updated)]
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.
Reconstructions of NAO index
Black: Instrumental NAO
Blue: Cook NAO
Red: Luterbacher et al NAO
Jones, P.D., Osborn, T.J. and Briffa,
K.R. “The evolution of climate over
the last millennium” Science 292,
2001, 662667
Global influence of
El Nino-Southern Oscillation
Reconstructions of ENSO Indices
Black: Instrumental SOI
Blue: Stahle et al SOI
Red: Mann et al Nino3 (x-1)
Jones, P.D., Osborn, T.J. and Briffa,
K.R. “The evolution of climate over
the last millennium” Science 292,
2001, 662667
CLIMATE FORCINGS
Volcanism
1000
1200
1400
1600
1800
Solar
Natural
Crowley, T.J., Causes of
Climate Change Over the
Past 1000 Years, Science,
289 270-277, 2000.
2000
CLIMATE FORCINGS
Anthropogenic
Greenhouse
Gases
Industrial
Aerosols
Climate Change 2001: The
Scientific Basis, Houghton, J.T.,
et al. (eds.), Cambridge Univ.
Press, Cambridge, 2001
Jones, P.D., Mann, M.E., Climate
Over Past Millennia, Reviews of
Geophysics, 42, RG2002,
doi:10.1029/2003RG000143, 2004.
Seasonal
Spatial
Patterns
Temperature Anomaly (oC)
Warm Season (MXD)
Cold Season (multiproxy)
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.
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.
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
“Maunder
Minimum”
1800
2000
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 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.
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
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, in revision, 2004.
Theoretical mechanism for natural
radiative forcing of El Nino
Theoretical mechanism for natural
radiative forcing of El Nino
Courtesy of E.Cook
CONCLUSIONS
•Proxy reconstructions and model simulations both suggest that
late 20th century hemispheric-scale warmth is anomalous in the
context of the past 1000-2000 years. Recent evidence suggests
that recent warmth at more regional scales, including Europe,
may be anomalous.
•Important 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.
•Forced changes in large-scale atmospheric circulation such as
the NAO, and internal dynamics related to El Nino, may play an
important role in explaining regional patterns of variability and
change in regions such as Europe, the Mediterranean, and
western North America.
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