Climate trends of the North American prairie pothole region 1906–2000

Abstract

The Prairie Pothole Region (PPR) is unique to North America. Its millions of wetlands and abundant ecosystem goods and services are highly sensitive to wide variations of temperature and precipitation in time and space characteristic of a strongly continental climate. Precipitation and temperature gradients across the PPR are orthogonal to each other. Precipitation nearly triples from west to east from approximately 300 mm/year to 900 mm/year, while mean annual temperature ranges from approximately 1 • C in the north to nearly 10 • C in the south. Twentieth-century weather records for 18 PPR weather stations representing 6 ecoregions revealed several trends. The climate generally has been getting warmer and wetter and the diurnal temperature range has decreased. Minimum daily temperatures warmed by 1.0 • C, while maximum daily temperatures cooled by 0.15 • C. Minimum temperature warmed more in winter than in summer, while maximum temperature cooled in summer and warmed in winter. Average annual precipitation increased by 49 mm or 9%. Palmer Drought Severity Index (PDSI) trends reflected increasing moisture availability for most weather stations; however, several stations in the western Canadian Prairies recorded effectively drier conditions. The east-west moisture gradient steepened during the twentieth century with stations in the west becoming drier and stations in the east becoming wetter. If the moisture gradient continues to steepen, B. Millett (B)

Wetlands inform how climate extremes influence surface water expansion and contraction

“…Previous research found lakes within the PPR to be important features that commonly experience extensive surface water expansion, subsuming adjacent wetlands during wet periods . These findings suggest that if climate conditions within the US portion of the PPR continue to get wetter, as predicted (e.g., Millett et al, 2009;McKenna et al, 2017), then both small wetland depressions and larger features, such as lakes and floodplains, will both serve critical roles in storing increased inputs of surface water, which could prevent downstream flooding.…”

“…This is particularly relevant when we consider the need for communities and local agencies to plan ahead for expected changes in the precipitation regime associated with climate change (Dore, 2005;Johnson et al, 2005;Millett et al, 2009;McKenna et al, 2017).…”

“…The drainage network across the PPR is increasingly modified with the expansion of ditch networks and tile drainage in association with agricultural activities (McCauley et al, 2015). These changes have accompanied extensive human-induced wetland loss across the region (Millett et al, 2009;Van Meter and Basu, 2015). Ditches, pipes and field tiles on the glacial till can hasten the speed with which water leaves a location and lower the water table through increased water withdrawal (De Laney, 1995;Blann et al, 2009;McCauley et al, 2015).…”

Recent climatic, cryospheric, and hydrological changes over the interior of western Canada: a review and synthesis

“…This led to widespread forest fires, low water levels in streams, lakes, and reservoirs and low soil moisture levels, and it was unusual in that it stretched over a vast area from Mexico to Alaska. Since the beginning of the 20th century there has been decadal-scale variability in drought occurrence as indicated by various precipitation and soil moisture indices, but there has been no consistent long-term trend in drought frequency or magnitude (Millett et al, 2009;Qian et al, 2010;Bonsal et al, 2013). This variability has tended to coincide primarily with precipitation variations modulated by largescale modes of oceanic-atmospheric circulation Shabbar and Skinner, 2004;Bonsal and Shabbar, 2008).…”

Midcontinent Prairie-Pothole Wetlands and Climate Change: an Introduction to the Supplemental Issue

“…Warming of Earth's climate is real (IPCC 2014), and there is strong scientific consensus of an anthropogenic cause (Cook et al 2013) with resultant changes already having widespread impacts on natural systems (IPCC 2014). During the past century, the average minimum daily temperature in the PPR has increased by 1°C and precipitation across the region has increased by about 9 % (Millett et al 2009). Global surface temperatures are projected to continue to rise throughout the 21st century (IPCC 2014), influencing water losses from wetlands as evapotranspiration rates change in response to warmer temperatures.…”