1. Reconstructing Past Climates
K Gajewski
Department of Geography, Environment and Geomatics
University of Ottawa
August 2016

2. What we are trying to do:
KR02
Western Victoria Island
Peros and Gajewski QSR

3. Reconstruction of past climates from pollen assemblages
Datasets needed
Spatial series of modern ‘calibration” data
Spatial series of climate (at each site
Methodology
Analogue method
Regression approach
Results
Time series
Maps
Regional averages

4. Reconstruction of past climates from pollen assemblages
Datasets needed
Spatial series of modern ‘calibration” data
Spatial series of climate (at each site
Methodology
Analogue method
Regression approach
Results
Time series
Maps
Regional averages

5. Microfossil Samples
14-C date
“Surface Sample”

7. Whitmore et al QSR

8. Total Annual Precipitation (mm)
Mean July Temp (oC)
Total Annual Precipitation (mm)
Anderson et al
J Biogeography

9. Reconstruction of past climates from pollen assemblages
Datasets needed
Spatial series of modern ‘calibration” data
Spatial series of climate (at each site
Methodology
Analogue method
Regression approach
Results
Time series
Maps
Regional averages

10. Methodology Dataset 1: core(s) – pollen assemblages
Dataset 2a: “modern” – pollen assemblages
Dataset 2b: modern climate at every modern pollen sample
Step 1: Calibrate modern pollen to modern climate
Step 2: Apply transfer function down-core
Alternative: Find closest analogue (statistical distance) of modern sample to every fossil sample; assign modern climate from that point to fossil point

11. Reconstruction of past climates from pollen assemblages
Datasets needed
Spatial series of modern ‘calibration” data
Spatial series of climate (at each site
Methodology
Analogue method
Regression approach
Results
Time series
Maps
Regional averages

12. Example: Reconstruction of a time series at one site
KR02
Western Victoria Island
Peros and Gajewski QSR

13. Comparison of reconstruction to instrumental data
Keizer and Gajewski RPP

14. Keizer and Gajewski. 2015. RPP

15. Example: map of climate at 6ka

16. Sawada et al.,
2004. QSR
Fig. 10. (a) 0 ka modern July temperature reconstructed at the 545 fossil sample sites. (b) 6 ka July temperature reconstructed at the 545 fossil pollen sample sites from the MAT, (c) July temperature anomalies (6–0 ka). (d) CCCma AGCM2 July temperature anomalies at model resolution.

17. Comparison to climate model
Sawada et al.,
2004. QSR

18. Example: Regional Average
Holocene
Viau et al J Geophysical Research 111, D09102,

19. Gajewski. 2008 Prog Phys Geogr 32:

20. Millennial-scale climate variability in the Holocene
Figure 2. (a) North American mean July temperature anomaly for the past 14,000 cal. yr. BP.
(b) Mean July temperature anomaly of the past 10,000 cal. yr. BP. Roman numerals identify four part division of the Holocene.
(c) Spectral analysis on detrended temperature anomaly curve of the last 14,000 cal. yr. BP.
Viau et al. 2005

21. For period of overlap, pollen based North American reconstruction compares well to tree-ring based Northern Hemisphere
Viau et al J Geophysical Research 111, D09102,