Climate Change in the Champlain Basin - The Nature Conservancy

Climate Change in the Champlain BasinIn the Adirondack uplands,which mark the westernborder of the ChamplainBasin, mean annual temperaturesrose by 1.5°F(0.8°C) between 1975 and2005, at a rate similar tothat of the Northeast as awhole (Stager et al., 2009).Statistically significantwarming occurred in June(+2.8°F, 1.6°C) and September(+4.7°F, 2.6°C), butno significant linear trendswere found in the othermonths. December diddisplay a prominent warmingtendency, but it wasstatistically indistinguishablefrom random variability inthat analysis.In this study, we find that the Champlain Basin has alsowarmed since the mid-1970s. A statistically significant riseof 2.1°F (1.2°C) occurred between 1976 and 2005 (Figure2), which suggests that the basin is warming even fasterthan the Adirondack uplands and the rest of the Northeast.In summer and autumn, respectively, significant warmingof 2.0 and 3.6°F (ca. 1 and 2°C) occurred here, but springtemperatures displayed no reliable trend. Winter displayeda large increase (3.7°F, 2.1°C) but the linear trend wasnot statistically significant at the 5% level (though it wassignificant at the 10% level). This is in apparent contrast tothe aforementioned strong winter warming that NECIA hasreported for the northeastern states, but it is consistent withother recent analyses of weather records in northern NewYork and northwestern Vermont (Dello, 2007; Stager et al.,2009). These differences between local patterns and thosefound regionally and globally, as well as the variability of thetrends over time, again illustrate the need for current, placebasedanalyses such as those presented here.Figure 2. Temperatures averaged from eight USHCNweather stations in the Champlain Basin, arranged byseason, 1976–2005. The only statistically significantlinear warming trends were in the annual, summer andautumn records.Sixteen AOGCMs were available to us for advancedwatershed-scale analysis through Climate Wizard, whichincluded the smaller set of models used previously byNECIA for their regional analysis of the Northeast (fulldescriptions of all models are archived on the ClimateWizard Web site). Differences in their design cause thesemodels to produce a diversity of projections, especiallyfor precipitation and for variations among seasons, butthe general direction of temperature change is consistentamong all of them. Table 3 summarizes the predictionsfor 21st century warming in the Champlain Basin producedby each of the models for low (B1) and high (A2)emissions scenarios.10