Testing the Hockey Stick Mann Bradley and Hughes

Testing the ‘Hockey Stick’ Mann, Bradley and Hughes VS Mc. Intyre and Mc. Kitrick Laura Zaunbrecher EAS 4803 April 22, 2008

Overview • Proxy Data • Methods – Data Calibration – Principle Component Analysis – Comparison to Mann ‘ 98 Results – Temperature Reconstruction • Mann ‘Hockey Stick’ updates (vs. MM) • Conclusions

Proxy Data 14 used here- Original used 415 • 2 Ice Core d 18 O records from Quelccaya Ice Cap in Peru • 2 Ice Accumulation Records – Peru • Svalbard Ice Melt (summer air temp) • Greenland Ice Core d 18 O • N. Patagonia, Tasmania, Yakutia, NC, SC, GA precipitation (tree ring widths) • N. Patagonia, – dendrodensity • NA Tree line Data

Methods -Calibration • Each Proxy series is calibrated to the instrumental NH temperature record from 1880 to 1980

Mann EOF’s 1 and 2 Calibration should capture at least these first 2 EOFS Increasing temp ENSO

Principle Component Analysis -Retain up to the 4 th Principle Component -Ignore EOF Analysis -[u, s, v] =svd(A, ’econ’) A = U • W • VT

Principle Components NOISE!! =U(: , 1) HOCKEY STICK!!! =U(: , 2)

Comparison to MBH 98 MUCH Noiser (more variant) than the complete dataset Hockey Stick is captured in PC 2 Other PC’s are just Noise – likely from using only 14 Proxies Versus the 415 used in MBH 98

Temperature Reconstruction Mann et al. , 1998 -’Hockey Stick Temperature Spike ~0. 3°C -Smaller Amplitude than found by MBH -Large Interdecadal Oscillations -Lots of Noise!!!!

Mc. Intyre and Mc. Kitrick argue… • Mann’s NHtemp reconstruction gives too much weight to PC 1 and bristlecone pine Corrcoef(Mann. NHtemp, Mann. PC 1) = 0. 8765 Coorcoef(Mann. NHtemp, Bristlecone) =0. 5144

Uses different calibration intervals Psuedo-proxy study Uses different statiscital technique –Reg. EM STILL GET THE HOCKEY STICK!!!!

Conclusions • Majority of Signal is Noise • Do not capture ENSO in PC’s when using the 14 proxies in this study • Skipped some important steps – Verification, Weights (proxies were weighted equally here) • DO get the ‘Hockey Stick’ as the major form of temperature variation (after noise) • Global Warming is REAL!

Questions?