Uncertainty in the impacts of projected climate change on the hydrology of a subarctic environment: Liard River Basin

Abstract

Abstract. Like many high latitude areas, the mountainous region of subarctic Canada has experienced recent warming and is an area of large inter-annual temperature variations, most notably during the winter. Quantifying how climate tendencies affect streamflow, especially in the spring melt season, is critical not only to regional water resource management, but to understanding the influence of freshwater on the Arctic sea-ice cover and global climate system. The impact of projected atmospheric warming on the discharge of the Liard River is unclear. Here, uncertainty in climate projections associated with GCM structure (2 • C prescribed warming) and magnitude of increases in global mean air temperature (1 to 6 • C) on the river discharge are assessed using a well-tested, semi-distributed hydrological model. Analyses have shown that the hydrological impacts are highly dependant on the GCM scenario. Uncertainties between the GCM scenarios are driven by the inconsistencies in projected spatial variability and magnitude of precipitation, rather than warming temperatures. Despite these uncertainties, the entire scenario simulations project that the subarctic nival regime will be preserved in the future, but the magnitude of change in river discharge is highly uncertain. Generally, spring freshet will arrive earlier, autumn to spring discharge will increase whereas summer flow will decrease, leading to an overall increase in annual discharge.

The fate of lake ice in the North American Arctic

“…Zhang et al, 2007;Kaufmann et al, 2009) and those trends are predicted to continue with future climate scenarios (e.g., ACIA, 2005;Bonsal and Kochtubajda, 2009). From a hydrological perspective little work has been done for this region examining future changes, however, GCMs have been used in combination with hydrological models to predict changes within a small headwater basin (Pohl et al, 2007) and the larger Liard Basin (Woo et al, 2008;Thorne, 2011). River ice duration by 2050 for most of Canada is estimated to be approximately 20 days shorter than , based on projected changes to the 0 • isotherm (Prowse et al, 2007).…”

Improving pan-European hydrological simulation of extreme events through statistical bias correction of RCM-driven climate simulations

“…Particularly, small-scale patterns of precipitation are highly dependent on climate model resolution and parametrization. At the same time, some RCMs show systematic biases with a clear tendency to enhance these biases in more extreme cold or warm conditions (van der Linden and Mitchell, 2009). In a pan-European context, it has been noticed that climate models tend to overestimate warm summers in south-eastern Europe whereas precipitation in winter is too abundant in northern Europe Christensen et al, 2008).…”

“…Shabalova et al, 2003;Lenderink et al, 2007;van Pelt et al, 2009;Hurkmans et al, 2010). As a result, several techniques to correct potential bias in precipitation and temperature have been developed.…”

“…In recent years, several studies have appeared that implement this technique to assess the impacts of climate change on hydrological extremes, either at the local (e.g. Middelkoop et al, 2001;Etchevers et al, 2002;Prudhomme et al, 2003;Kleinn et al, 2005;Wilby et al, 2006;Steele-Dunne et al, 2008;Thorne, 2011), regional (e.g. Graham et al, 2007) or continental (e.g.…”

“…Wood et al, 2004) and it can result in unwanted uncertainty regarding projected climate change (van der Linden and Mitchell, 2009). More specifically, RCM outputs not corrected for biases tend to produce inaccurate probabilities for extreme events, thus rendering the extreme value analysis less reliable (Durman et al, 2001).…”