Abstract (from ScienceDirect): Paleohydrologic records can provide unique, long-term perspectives on streamflow variability and hydroclimate for use in water resource planning. Such long-term records can also play a key role in placing both present day events and projected future conditions into a broader context than that offered by instrumental observations. However, relative to other major river basins across the western United States, a paucity of streamflow reconstructions has to date prevented the full application of such paleohydrologic information in the Upper Missouri River Basin. Here we utilize a set of naturalized streamflow records for the Upper Missouri and an expanded network of tree-ring records to reconstruct streamflow at thirty-one gaging locations across the major headwaters of the basin. The reconstructions explain an average of 68% of the variability in the observed streamflow records and extend available records of streamflow back to 886 CE on average. Basin-wide analyses suggest unprecedented hydroclimatic variability over the region during the Medieval period, similar to that observed in the Upper Colorado River Basin, and show considerable synchrony of persistent wet-dry phasing with the Colorado River over the last 1200 years. Streamflow estimates in individual sub-basins of the Upper Missouri demonstrate increased spatial variability in discharge during the Little Ice Age (∼1400–1850 CE) compared with the Medieval Climate Anomaly (∼800–1400 CE). The network of streamflow reconstructions presented here fills a major geographical void in paleohydrologic understanding and now allows for a long-term assessment of hydrological variability over the majority of the western U.S.

From Summary: "The North American Prairie Pothole Region (PPR) is an expansive region that covers parts of five Midwestern states and three Canadian provinces. The region contains millions of wetlands that produce between 50–80% of the continent’s waterfowl population each year. Previous modeling efforts indicated that climate change would result in a shift of suitable waterfowl breeding habitat from the central PPR to the southeast portion of the region where over half of wetlands have been drained. The implications of adopting these projections would require a massive investment in wetland restoration in the southeastern PPR to sustain migratory waterfowl populations at harvestable levels. We revisited these projections using a newly developed model for simulating prairie-pothole wetland hydrology in combination with the most up-to-date climate model projections to estimate how future climate may impact the distribution of waterfowl-breeding habitat. We also presented our findings in changes to wet May ponds, which is a metric that is used by managers at the US Fish and Wildlife Service to estimate waterfowl breeding populations to establish harvest regulations. Based on the output of 32 climate models and 2 emission scenarios we found a projected change in wet May pond numbers from -23% to +.02% when comparing the most recent climate period (1989–2018) to the end of the 21st century (2070–2099). We also found no evidence that the distribution of wet May ponds will shift in the future. These results suggest that management and conservation strategies for wetlands in the PPR that focus on areas with the high densities of intact wetland basins support large numbers of breeding duck pairs and will likely be the most successful in maintaining habitats critical to continental waterfowl populations."

Abstract (from PNAS): Recent decades have seen droughts across multiple US river basins that are unprecedented over the last century and potentially longer. Understanding the drivers of drought in a long-term context requires extending instrumental data with paleoclimatic data. Here, a network of new millennial-length streamflow reconstructions and a regional temperature reconstruction from tree rings place 20th and early 21st century drought severity in the Upper Missouri River basin into a long-term context. Across the headwaters of the United States’ largest river basin, we estimated region-wide, decadal-scale drought severity during the “turn-of-the-century drought” ca. 2000 to 2010 was potentially unprecedented over the last millennium. Warming temperatures have likely increasingly influenced streamflow by decreasing runoff efficiency since at least the late 20th century.