The 2014/15 Snowpack Drought in Washington State and its Climate Forcing

• Published in: Bulletin of the American Meteorological Society
• Main Authors: Fosu, Boniface O., Wang, S.-Y. Simon, Yoon, Jin-Ho
• Other Authors: American Meteorological Society
• Format: Text
• Language: unknown
• Published: Hosted by Utah State University Libraries 2017
• Subjects: earth atmosphere; meterology; anthropogenic warming; climate forcings; high temperature; nocvl; washinton state; drought; Plant Sciences; Arctic; Pacific; Climate change; Sea ice; Alaska
• Online Access: https://digitalcommons.usu.edu/psc_stures/2; https://doi.org/10.1175/BAMS-D-16-0154.1

This fifth edition of explaining extreme events of the previous year (2015) from a climate perspective continues to provide evidence that climate change is altering some extreme event risk. Without exception, all the heat-related events studied in this year’s report were found to have been made more intense or likely due to human-induced climate change, and this was discernible even for those events strongly influenced by the 2015 El Niño. Furthermore, many papers in this year’s report demonstrate that attribution science is capable of separating the effects of natural drivers including the strong 2015 El Niño from the influences of long-term human-induced climate change. Other event types investigated include cold winters, tropical cyclone activity, extreme sunshine in the United Kingdom, tidal flooding, precipitation, drought, reduced snowpack in the U.S. mountain west, arctic sea ice extent, and wildfires in Alaska. Two studies investigated extreme cold waves and monthly-mean cold conditions over eastern North America during 2015, and find these not to have been symptomatic of human-induced climate change. Instead, they find the cold conditions were caused primarily by internally generated natural variability. One of these studies shows winters are becoming warmer, less variable, with no increase in daily temperature extremes over the eastern United States. Tropical cyclone activity was extreme in 2015 in the western North Pacific (WNP) as measured by accumulated cyclone energy (ACE). In this report, a study finds that human-caused climate change largely increased the odds of this extreme cyclone activity season. The 2015 Alaska fire season burned the second largest number of acres since records began in 1940. Investigators find that human-induced climate change has increased the likelihood of a fire season of this severity. Confidence in results and ability to quickly do an attribution analysis depend on the “three pillars” of event attribution: the quality of the observational record, the ability of models ...