1. Testing the ‘Hockey Stick’
Mann, Bradley
and Hughes
McIntyre
and McKitrick VS
Laura Zaunbrecher
EAS 4803
April 22, 2008

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

4. Proxy Data 14 used here- Original used 415
2 Ice Core d18O records from Quelccaya Ice Cap in Peru
2 Ice Accumulation Records – Peru
Svalbard Ice Melt (summer air temp)
Greenland Ice Core d18O
N. Patagonia, Tasmania, Yakutia, NC,SC, GA precipitation (tree ring widths)
N. Patagonia, – dendrodensity
NA Tree line Data

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

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

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

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

9. Comparison to MBH98
MUCH Noiser (more variant) than the complete dataset
Hockey Stick is captured in PC2
Other PC’s are just Noise – likely from using only 14 Proxies
Versus the 415 used in MBH98

10. 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!!!!

11. McIntyre and McKitrick argue…
Mann’s NHtemp reconstruction gives too much weight to PC1 and bristlecone pine
Corrcoef(MannNHtemp, MannPC1) =
Coorcoef(MannNHtemp,Bristlecone)
=0.5144

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

13. 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!

14. Questions?