PSU METEO 004 - Comparisons of Observed Paleoclimate and Model

Unformatted text preview:

Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Documentary evidence of change in seasonal rangeSlide 11Detection of “unusual” warming trendsSlide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Simulated and reconstructed changes in seasonal rangeSlide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Simulated changes in seasonal range over last 150 yearsComparisons of Observed Paleoclimate and Model-Based Studies of Climate Changes Over the Past Two MillenniaDepartment of Environmental Sciences, University of Virginia, Charlottesville, VACLIVAR 2004Baltimore, MDJune 23, 2004Collaborators: B. Adams, C. Ammann, R. Bradley; M. Cane; A. Clement, T. Delworth; M.K. Hughes, T. Osborn; P. Jones, S. Rutherford; G. Schmidt; D. Shindell; S. ZebiakMichael E. MannKeith BriffaClimatic Research UnitUniversity of East Anglia, UKMann, 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)]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)]Greater variability in extratropics and summer!Empirical Proxy-Based Climate Reconstructions1. Sensitivity to scaling/calibrationOsborn, T.J., and K.R. Briffa, Comments on the paper of R. N. Harris and D.S. Chapman "Mid-latitude (30'N-60'N) climate warming inferred by combining borehole temperatures with surface air temperatures", Geophysical Research Letters, 29 (16), (45)1-2, 2002.www.cru.uea.ac.uk/cru/projects/soap/From Briffa, Osborn and Schweingruber (2003) Glob Planet ChangeComparison is difficult because each reconstruction uses a different season, region and calibration periodExample shows a comparison after re-scaling every series against annual or warm-season temperature averaged over all land north of 20°N over a common 1881-1960 periodMann1999(land north of 20N extractedfrom spatial reconstructions)Esper2002 Briffa2000 Briffa2001Jones19982. Sensitivity to target region and season2. Sensitivity to target region and seasonComparison between Briffa et al. NH extratropical warm-season NH mean temperature reconstruction with RegEM reconstructionRutherford, 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.(a) unmaskedComparison between Briffa et al. NH extratropical warm-season NH mean temperature reconstruction with RegEM reconstruction(a) unmasked (b) maskedRutherford, 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), 2004.2. Sensitivity to target region and seasonComparison between Briffa et al. NH extratropical warm-season NH mean temperature reconstruction with RegEM reconstruction(a) unmasked (b) masked(c) based on Esper et al (2002) locations onlyRutherford, 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), 2004.2. Sensitivity to target region and seasonwww.cru.uea.ac.uk/cru/projects/soap/From Jones, Osborn and Briffa (2003) J Geophys ResDocumentary evidence of change in seasonal rangeManley/ParkerVan EngelenPfisterBrazdilWangWang2. Sensitivity to target region and seasonModel/Data ComparisonsDetection of “unusual” warming trendsCompare observed trends during the 20th century with the95th percentile of pre-20th century “natural variability” trendswww.cru.uea.ac.uk/cru/projects/soap/Analysis from Tim Osborn (CRU, UEA, UK)1991-2000 trend1966-2000 trend1936-2000 trend1901-2000 trendObserved warming overvarious periods ending in 2000Three estimates of “natural” variability:Reconstruction1 (from tree-rings withlow-frequency standardisation)Reconstruction2 (from tree-rings withtraditional standardisation)Model (1000-yr HadCM3 control run)“Unusual” warming is detectedfor cases with observed warmingexceeding all three 95th percentilesof “natural” variabilityThe temperature in this exampleis extended summer temperatureaveraged over all land north of 20N.Natural1000 1200 1400 1600 1800 2000VolcanismSolarCLIMATE FORCINGSCrowley, T.J., Causes of Climate Change Over the Past 1000 Years, Science, 289 270-277, 2000.CLIMATE FORCINGSAnthropogenicGreenhouse GasesIndustrial AerosolsClimate Change 2001: The Scientific Basis, Houghton, J.T., et al. (eds.), Cambridge Univ. Press, Cambridge, 2001Jones, P.D., Mann, M.E., Climate Over Past Millennia, Reviews of Geophysics, 42, RG2002, doi:10.1029/2003RG000143, 2004.www.cru.uea.ac.uk/cru/projects/soap/Data comparison from Tim Osborn (CRU, UEA, UK)Last 500 years, 10-year smoothingNorthern extratropics summer temperatureTree-ring densityreconstructionHadCM3 ObservationsECHAM4-HOPELIA winter cooling in Europe associated with an NAO trend due to solar irradiance changes, interacting w/ stratospheric atmospheric dynamics and chemistryEmpiricalNASA/GISS ModelEuropean Winter Cooling During the Little Ice Age 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, 2149-2152, 2001.Proxy basedreconstruction GCM Solar + Volcanic patternsAnnual averagelate 17th vs late 18th Century Temperature changeShindell, 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.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 Radiative Summer CoolingEnsemble average summer (Jun-Aug) surface


View Full Document

PSU METEO 004 - Comparisons of Observed Paleoclimate and Model

Documents in this Course
Load more
Download Comparisons of Observed Paleoclimate and Model
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Comparisons of Observed Paleoclimate and Model and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Comparisons of Observed Paleoclimate and Model 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?