scholarly journals Mid-twenty-first century climate change in the Central United States. Part II: Climate change processes

2012 ◽  
Vol 40 (3-4) ◽  
pp. 569-583 ◽  
Author(s):  
C. M. Patricola ◽  
K. H. Cook
Keyword(s):  
Climate Change ◽  
United States ◽  
First Century ◽  
Change Processes ◽  
Central United States ◽  
Twenty First Century

scholarly journals Watershed-Scale Response to Climate Change through the Twenty-First Century for Selected Basins across the United States

2011 ◽  
Vol 15 (17) ◽  
pp. 1-37 ◽  
Author(s):  
Lauren E. Hay ◽  
Steven L. Markstrom ◽  
Christian Ward-Garrison
Keyword(s):  
Climate Change ◽  
United States ◽  
Coupled Model ◽  
The United States ◽  
Lessons Learned ◽  
First Century ◽  
Emission Scenarios ◽  
Watershed Model ◽  
Geographical Regions ◽  
Twenty First Century

Abstract The hydrologic response of different climate-change emission scenarios for the twenty-first century were evaluated in 14 basins from different hydroclimatic regions across the United States using the Precipitation-Runoff Modeling System (PRMS), a process-based, distributed-parameter watershed model. This study involves four major steps: 1) setup and calibration of the PRMS model in 14 basins across the United States by local U.S. Geological Survey personnel; 2) statistical downscaling of the World Climate Research Programme’s Coupled Model Intercomparison Project phase 3 climate-change emission scenarios to create PRMS input files that reflect these emission scenarios; 3) run PRMS for the climate-change emission scenarios for the 14 basins; and 4) evaluation of the PRMS output. This paper presents an overview of this project, details of the methodology, results from the 14 basin simulations, and interpretation of these results. A key finding is that the hydrological response of the different geographical regions of the United States to potential climate change may be very different, depending on the dominant physical processes of that particular region. Also considered is the tremendous amount of uncertainty present in the climate emission scenarios and how this uncertainty propagates through the hydrologic simulations. This paper concludes with a discussion of the lessons learned and potential for future work.

scholarly journals Using Tree Rings to Predict the Response of Tree Growth to Climate Change in the Continental United States during the Twenty-First Century

2010 ◽  
Vol 14 (19) ◽  
pp. 1-20 ◽  
Author(s):  
A. Park Williams ◽  
Joel Michaelsen ◽  
Steven W. Leavitt ◽  
Christopher J. Still
Keyword(s):  
Climate Change ◽  
United States ◽  
Tree Ring ◽  
Tree Growth ◽  
Ring Width ◽  
First Century ◽  
Annual Growth ◽  
Climate Variations ◽  
Tree Ring Data ◽  
Twenty First Century

Abstract In the early 1900s, tree-ring scientists began analyzing the relative widths of annual growth rings preserved in the cross sections of trees to infer past climate variations. Now, many ring-width index (RWI) chronologies, each representing a specific site and species, are archived online within the International Tree-Ring Data Bank (ITRDB). Comparing annual tree-ring-width data from 1097 sites in the continental United States to climate data, the authors quantitatively evaluated how trees at each site have historically responded to interannual climate variations. For each site, they developed a climate-driven statistical growth equation that uses regional climate variables to model RWI values. The authors applied these growth models to predict how tree growth will respond to twenty-first-century climate change, considering four climate projections. Although caution should be taken when extrapolating past relationships with climate into the future, the authors observed several clear and interesting patterns in the growth projections that seem likely if warming continues. Most notably, the models project that productivity of dominant tree species in the southwestern United States will decrease substantially during this century, especially in warmer and drier areas. In the northwest, nonlinear growth relationships with temperature may lead to warming-induced declines in growth for many trees that historically responded positively to warmer temperatures. This work takes advantage of the unmatched temporal length and spatial breath of annual growth data available within the ITRDB and exemplifies the potential of this ever-growing archive of tree-ring data to serve in meta-analyses of large-scale forest ecology.

scholarly journals Statistical Comparisons of Watershed-Scale Response to Climate Change in Selected Basins across the United States

2011 ◽  
Vol 15 (14) ◽  
pp. 1-26 ◽  
Author(s):  
John Risley ◽  
Hamid Moradkhani ◽  
Lauren Hay ◽  
Steve Markstrom
Keyword(s):  
Climate Change ◽  
United States ◽  
The United States ◽  
First Century ◽  
Energy Output ◽  
Daily Streamflow ◽  
Watershed Models ◽  
Monthly Streamflow ◽  
Twenty First Century ◽  
The Impact

Abstract In an earlier global climate-change study, air temperature and precipitation data for the entire twenty-first century simulated from five general circulation models were used as input to precalibrated watershed models for 14 selected basins across the United States. Simulated daily streamflow and energy output from the watershed models were used to compute a range of statistics. With a side-by-side comparison of the statistical analyses for the 14 basins, regional climatic and hydrologic trends over the twenty-first century could be qualitatively identified. Low-flow statistics (95% exceedance, 7-day mean annual minimum, and summer mean monthly streamflow) decreased for almost all basins. Annual maximum daily streamflow also decreased in all the basins, except for all four basins in California and the Pacific Northwest. An analysis of the supply of available energy and water for the basins indicated that ratios of evaporation to precipitation and potential evapotranspiration to precipitation for most of the basins will increase. Probability density functions (PDFs) were developed to assess the uncertainty and multimodality in the impact of climate change on mean annual streamflow variability. Kolmogorov–Smirnov tests showed significant differences between the beginning and ending twenty-first-century PDFs for most of the basins, with the exception of four basins that are located in the western United States. Almost none of the basin PDFs were normally distributed, and two basins in the upper Midwest had PDFs that were extremely dispersed and skewed.

Characterizing Climate-Change Impacts on the 1.5-yr Flood Flow in Selected Basins across the United States: A Probabilistic Approach

2011 ◽  
Vol 15 (18) ◽  
pp. 1-16 ◽  
Author(s):  
John F. Walker ◽  
Lauren E. Hay ◽  
Steven L. Markstrom ◽  
Michael D. Dettinger
Keyword(s):  
Climate Change ◽  
United States ◽  
Probabilistic Approach ◽  
The United States ◽  
Empirical Orthogonal Functions ◽  
First Century ◽  
Climate Projections ◽  
Climate Change Scenarios ◽  
Twenty First Century ◽  
Temporal Shifts

Abstract The U.S. Geological Survey Precipitation-Runoff Modeling System (PRMS) model was applied to basins in 14 different hydroclimatic regions to determine the sensitivity and variability of the freshwater resources of the United States in the face of current climate-change projections. Rather than attempting to choose a most likely scenario from the results of the Intergovernmental Panel on Climate Change, an ensemble of climate simulations from five models under three emissions scenarios each was used to drive the basin models. Climate-change scenarios were generated for PRMS by modifying historical precipitation and temperature inputs; mean monthly climate change was derived by calculating changes in mean climates from current to various future decades in the ensemble of climate projections. Empirical orthogonal functions (EOFs) were fitted to the PRMS model output driven by the ensemble of climate projections and provided a basis for randomly (but representatively) generating realizations of hydrologic response to future climates. For each realization, the 1.5-yr flood was calculated to represent a flow important for sediment transport and channel geomorphology. The empirical probability density function (pdf) of the 1.5-yr flood was estimated using the results across the realizations for each basin. Of the 14 basins studied, 9 showed clear temporal shifts in the pdfs of the 1.5-yr flood projected into the twenty-first century. In the western United States, where the annual peak discharges are heavily influenced by snowmelt, three basins show at least a 10% increase in the 1.5-yr flood in the twenty-first century; the remaining two basins demonstrate increases in the 1.5-yr flood, but the temporal shifts in the pdfs and the percent changes are not as distinct. Four basins in the eastern Rockies/central United States show at least a 10% decrease in the 1.5-yr flood; the remaining two basins demonstrate decreases in the 1.5-yr flood, but the temporal shifts in the pdfs and the percent changes are not as distinct. Two basins in the eastern United States show at least a 10% decrease in the 1.5-yr flood; the remaining basin shows little or no change in the 1.5-yr flood.

Great Plains Precipitation and Its SST Links in Twentieth-Century Climate Simulations, and Twenty-First- and Twenty-Second-Century Climate Projections

2010 ◽  
Vol 23 (23) ◽  
pp. 6409-6429 ◽  
Author(s):  
Alfredo Ruiz-Barradas ◽  
Sumant Nigam
Keyword(s):  
United States ◽  
Twentieth Century ◽  
Great Plains ◽  
Summer Precipitation ◽  
Precipitation Variability ◽  
Second Century ◽  
First Century ◽  
Climate Simulations ◽  
Central United States ◽  
Twenty First Century

Abstract The present work assesses spring and summer precipitation over North America as well as summer precipitation variability over the central United States and its SST links in simulations of the twentieth-century climate and projections of the twenty-first- and twenty-second-century climates for the A1B scenario. The observed spatial structure of spring and summer precipitation poses a challenge for models, particularly over the western and central United States. Tendencies in spring precipitation in the twenty-first century agree with the observed ones at the end of the twentieth century over a wetter north-central and a drier southwestern United States, and a drier southeastern Mexico. Projected wetter springs over the Great Plains in the twenty-first and twenty-second centuries are associated with an increase in the number of extreme springs. In contrast, projected summer tendencies have demonstrated little consistency. The associated observed changes in SSTs bear the global warming footprint, which is not well captured in the twentieth-century climate simulations. Precipitation variability over the Great Plains presents a coherent picture in spring but not in summer. Models project an increase in springtime precipitation variability owing to an increased number of extreme springs. The number of extreme droughty (pluvial) events during the spring–fall part of the year is under(over)estimated in the twentieth century without consistent projections. Summer precipitation variability over the Great Plains is linked to SSTs over the Pacific and Atlantic Oceans, with no apparent ENSO link in spite of the exaggerated variability in the equatorial Pacific in climate simulations; this has been identified already in observations and atmospheric models forced with historical SSTs. This link is concealed due to the increased warming in the twenty-first century. Deficiencies in land surface–atmosphere interactions and global teleconnections in the climate models prevent them from a better portrayal of summer precipitation variability in the central United States.

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