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Home > Projects
Climatic Extremes in Southern Manitoba during the Past Millennium (2001)
This was a multi-faceted study. The first component involves the determination of the annual ambient moisture conditions from the analysis of a continuous record of tree growth rings going back 700 years. The second component is a study of silt deposits in Lake Winnipeg using bottom mud cores reaching back to more than 1000 years.
Climatic Extremes in Southern Manitoba during the Past Millennium. This project was able to exploit and extend results from a related ongoing project. The first component involves the determination of the annual ambient moisture conditions from the analysis of a continuous record of tree growth rings going back 700 years. The trees used are bur oaks living or having grown in the narrow forested margin of the Red River and Assiniboine valleys. Growth rings of living trees were first correlated with the historical weather records, and cross-dating techniques were used to extend the tree ring data back in time. Temperature changes, clear-cutting and insect infestations may be significant, secondary factors affecting tree growth - it is recommended that these be investigated in the future. The analysis was able to identify, among others, a period of 75 consecutive dry years around the 1700's, which is much longer that any drought observed since colonisation. Between 1661 and 1774, the frequency of below-normal annual precipitation seems to have been as high as 2 out of 3 years, while annual precipitation was at its highest around 1600.
The second component is a study of silt deposits in Lake Winnipeg using bottom mud cores reaching back to more than 1000 years. Dating of lake bottom cores cannot be as accurate as for tree rings (tens of years near the top, 100's of years at the bottom), but the analysis nevertheless reveals significant past excursions of some of the parameters from the conditions prevailing in more recent times. More accurate dating and analysis should be completed within the next year. Also, it is recommended that the mud core analysis be related to the tree ring analysis.
Information dated October 26th, 2001 and found here
| Team | Erik Nielsen |
| Funding | $25,000 |
| Collaborators | Manitoba Geological Survey |