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and the impacts on ecological integrity, led to increasing controversy, which raged for over 40
years, with industry, first nations, and ecologists all vying to protect their interests in the face
of an increasingly uncertain future (Wolfe et al. 2007, Wolfe et al. 2012).
These arguments were completely reframed once recent lake levels were put into a broader,
palaeo-environmental perspective. Tree ring studies showed that similar low lake levels had
occurred several times since the early nineteenth century (Figure 6.3a) (Stockton and Fritts
1973, Wolfe et al. 2012). Multiproxy palaeoecological work covering the past 5,200 years went on
to show that the 1971 lowstand was not uncommon in palaeohydrological terms, and further-
more, that the twentieth century was in fact an unusual period in the context of the past 1,000
years, with anomalously high water availability due to the melting of glaciers and ice-fields
that had accumulated during the Little Ice Age (LIA) (Wiklund et al. 2012, Wolfe et al. 2012). On
even longer time-scales, the Medieval Warm Period (MWP) and mid-Holocene Altithermal
(MHA) showed much lower lake levels than the twentieth century average (Figure 6.3b). Flood
frequency was higher in MWP due to rapid spring melt, and was lower in the LIA when late
springs would make ice jams less likely. In the twentieth century, flood frequency and magni-
tude declined still further, because of decreasing snowmelt and runoff, a trend likely to con-
tinue into the future. Wolfe et al. (2012) concluded that if current trajectories continue, 2100 will
more closely resemble conditions of the MHA than the more recent past, and water manage-
ment needs are needed that adapt accordingly (Figure 6.3c) (Rasouli et al. 2012).
The case of Lake Athabasca shows how short-term records can skew interpretations of envi-
ronmental change. People's perceptions of changing lake levels and flood frequency were
based on societal memories, reflecting twentieth century conditions, which were revealed to
be highly unusual when viewed in the longer-term history of the lake. Furthermore, preoccu-
pation with local water management issues, specifically the construction of the Bennett Dam,
deflected attention away from regional warming and drying trends; similar trends of hydro-
logical variability were found in the Slave River Delta in the Northwest Territories (Wolfe et al.
2007). This co-occurrence of falling lake levels across the region suggested that regional rather
than local drivers might be in play. Tree ring studies from across the Rocky Mountains con-
firm that the twentieth century was regionally wetter compared with other centuries in the
past one thousand years, and droughts of greater severity were formerly much more common
(Jackson et al. 2009b). In the coming decades, warming temperatures and reduced high eleva-
tion precipitation and runoff from the Canadian Rocky Mountains will be associated with less
ice jam flooding, and future flooding patterns are expected to resemble the MWP, with flashy
spring floods (Figure 6.3c). As ice-jam floods are essential to replenishing perched basins in
the Peace-Athabasca Delta, these havens for wildlife may disappear in as little as 20 years,
with massive impacts on biodiversity and water resources (Wolfe et  al. 2012). Furthermore,
reduced discharge associated with lower rainfall and runoff will be exacerbated by increased
extraction by Alberta oil sands industry and other social demands (Wolfe et al. 2012).
At a time of increasing water demand, driven by local social and economic factors, there
are also global climatic drivers in play that will reduce water supply, suggesting future water
scarcity at an unprecedented scale. The palaeoecological work revealed how a short-term
focus was obscuring opportunities for adaptation that are needed in the coming decades.
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