Liying Xu
MSc student, PEARL Lab Understanding spatial patterns of past aridity on the Canadian prairies over the Holocene: Insights based on diatom assemblages from Success Lake The Canadian prairies receive limited precipitation and hence are prone to drought-related environmental, economic, and social impacts. Previous studies have suggested the Canadian prairies are highly subject to extreme drought in the future that resembles the mid-Holocene,which is when many lakes have dried out. Understanding the Holocene aridity profile is critical for us to be able to confidently forecast future drought and aridity, which is essential to establish appropriate policies and programs to reduce negative impacts. I used diatom outer scales buried in Success Lake sediment to reconstruct changes in lake water salinity, which could indicate the change in the aridity over the Holocene on the Canadian prairies. Diatom record from Success Lake revealed four stages of aridity change in its vicinity over the Holocene. Century-scale analysis of the diatom record during the Holocene is consistent with a drier climate in the early-mid Holocene (between 7000 to 5300 yr BP). An abrupt decrease in diatom-inferred salinity between 5300 cal yr BP to 3300 yr BP indicates the onset of a wetter climate, with continuing arid conditions throughout the mid-Holocene. Analysis of the past ~3000 years suggests that the late Holocene was more complex, with extended periods of increased variability in precipitation, characterized by frequent oscillation between the rise and falls in effective moisture. Comparing the aridity record from Success Lake with other paleoclimatic records from the Canadian prairie revealed a west-east moisture variability gradient, showing coherency within western and eastern sites and with opposite trends among the two groups. The mechanism controlling the moisture gradient is likely associated with the positioning and shaping of the jet stream, influenced by ocean-atmospheric interaction and solar radiation. Natural shifts in moisture availability may accelerate global warming, further reducing the precipitation and intensifying the likelihood of extreme drought over the Canadian prairie. Comments are closed.
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