Author : Wig, J.A. Date : 1992. Title : A Proxy Record of Recent Climatic Change in the Mount Rae Area, Canadian Rocky Mountains. Publication : Unpublished M.Sc. thesis. University of Saskatchewan, Saskatoon, Saskatchewan. Issue : Page(s) : 106 p.
The purpose of this study was to investigate the rate and magnitude of recent climatic change in an alpine area of the Canadian Rocky Mountains. Since there is very little long-term climate data available for this area, the primary objective was to produce a climatic record through an analysis of annual variations in tree ring growth. Engelmann spruce trees (Picea engelmannii (Parry) Engelm.) were sampled at two study sites in the Mount Rae area (Elbow Lake alluvial fan (161 trees), Highwood Summit (32 trees) of southwestern Alberta in the summer of 1990. It was anticipated that trees on the first site would yield a record of macroclimatic variations and provide a temporal record of geomorphic disturbance. A stronger macroclimatic signal was anticipated at the second site. Multiple tree cores were collected from each site using an increment corer. The measured and dated tree-ring widths were checked with COFECHA and then standardized with INDEX to remove growth trends. Ring-width chronologies for each site were then produced. The relationship between mean monthly temperature and total monthly precipitation and tree growth was evaluated using a response function analysis (RESPONSE). This analysis identified temperature of the growing season as the climatic variable most influential to ring-width development. A transfer function, used to estimate June/July mean temperature from a ring-width chronology, was calibrated and verified. The site chronologies indicated that summer temperature decline from approximately 1675 to 1700, 1810 to 1850 and 1950 to 1980. The highest summer temperatures were recorded during the early to middle 17th century, 1775 to 1800, and 1900 to 1950. Confirmation of the validity of this proxy climate record for the Mount Rae area is expressed in the similarity to temperature trends developed in other dendroclimatic studies for the Canadian Rocky Mountains.