This Title All WIREs
How to cite this WIREs title:
WIREs Clim Change
Impact Factor: 7.385

North American megadroughts in the Common Era: reconstructions and simulations

Full article on Wiley Online Library:   HTML PDF

Can't access this content? Tell your librarian.

During the Medieval Climate Anomaly (MCA), Western North America experienced episodes of intense aridity that persisted for multiple decades or longer. These megadroughts are well documented in many proxy records, but the causal mechanisms are poorly understood. General circulation models (GCMs) simulate megadroughts, but do not reproduce the temporal clustering of events during the MCA, suggesting they are not caused by the time history of volcanic or solar forcing. Instead, GCMs generate megadroughts through (1) internal atmospheric variability, (2) sea‐surface temperatures, and (3) land surface and dust aerosol feedbacks. While no hypothesis has been definitively rejected, and no GCM has accurately reproduced all features (e.g., timing, duration, and extent) of any specific megadrought, their persistence suggests a role for processes that impart memory to the climate system (land surface and ocean dynamics). Over the 21st century, GCMs project an increase in the risk of megadrought occurrence through greenhouse gas forced reductions in precipitation and increases in evaporative demand. This drying is robust across models and multiple drought indicators, but major uncertainties still need to be resolved. These include the potential moderation of vegetation evaporative losses at higher atmospheric [CO2], variations in land surface model complexity, and decadal to multidecadal modes of natural climate variability that could delay or advance onset of aridification over the the next several decades. Because future droughts will arise from both natural variability and greenhouse gas forced trends in hydroclimate, improving our understanding of the natural drivers of persistent multidecadal megadroughts should be a major research priority. WIREs Clim Change 2016, 7:411–432. doi: 10.1002/wcc.394 This article is categorized under: Paleoclimates and Current Trends > Paleoclimate Climate Models and Modeling > Knowledge Generation with Models
Regional average PDSI time series from the updated version of the North American Drought Atlas: California–Nevada (32°N–41°N, 126°W–114°W), the Southwest (28°N–38°N, 114°W–103°W), and the Central Plains (33°N–45°N, 103°W–90°W). Gray line is a smoothed version of the PDSI time series, using a 10‐year loess smooth.
[ Normal View | Magnified View ]
Tree‐ring chronology network for various years in the updated version of the North American Drought Atlas. The new network uses 1,936 chronologies.
[ Normal View | Magnified View ]
As Figure , but highlighting other major megadrought periods.
[ Normal View | Magnified View ]
As Figure , but for the periods coinciding with the abandonment of the Ancestral Puebloan (a) and Cahokia (b) Native American settlements.
[ Normal View | Magnified View ]
Multiyear average PDSI from the updated drought atlas for the first (a) and second (b) of the centennial scale Stine megadroughts.
[ Normal View | Magnified View ]

Browse by Topic

Paleoclimates and Current Trends > Paleoclimate
Climate Models and Modeling > Knowledge Generation with Models

Access to this WIREs title is by subscription only.

Recommend to Your
Librarian Now!

The latest WIREs articles in your inbox

Sign Up for Article Alerts