West Coast Drought
The scientific community investigating climate change does not debate its existence but rather the nuances of how our climate is transitioning to accommodate the anthropogenic emissions of greenhouse gasses. A particularly deliberated topic within the overall climate change discussion is how the occurrence and duration of droughts are being influence. Some climatologists predict that droughts will occur more frequently and for longer durations as the climate continues its warming trend, while others argue that data collection on climate conditions has become more precise and therefore better captures extremes. The latter theory argued that the extremes in the newer data (from the more precise equipment) paints a more turbulent climate than in previous recordings where the extremes would have been missed or averaged into the mean by the older sensors lack of precision.
Regardless of the scientific debate, turbulent weather has become a common theme across the country. After a historically dry spring and summer drought in 2012, the Midwest recorded one of the wettest springs in 2013. As I write this blog from my office in a typically rainy Seattle, we have received only half of the rainfall that on average falls from October to January and I have the possibility of a sunny afternoon to enjoy. The dry climate in Seattle is indicative of the larger drought currently afflicting the entire western U.S. The image below indicates the severity of the drought currently impacting the west, particularly California.
Winter droughts have strong repercussions on the western U.S. water supplies because reservoirs in the region are prrimarily recharged by winter snowpack melting from the mountains in the spring. With the current drought, winter snowpack across the West is dramatically below the year-to-date averages. The image below shows the disparity in Western snowpack by January 17 from last year and this year.
The Sierra Mountains have 20-25% of the winter snowpack that is typically present by this time of year. There is, however, still time to make up for the lack of snow in western ranges and avert the threat of lowered reservoirs and dry forests. The current high-pressure ridge sits off the Pacific coast will continue to push the moisture packed low pressure fronts that would typically hit the Sierra and Cascade Mountain ranges are being pushed north towards Alaska Northern British Columbia. In the coming days, the high-pressure system that is further instigating the drought will eventually move on, and the typical moisture that falls this time of year should return. The test will be whether the shortfall in snow can be made up by the time the spring thaw hits. And, the question that the current drought forces us to ask is can we put some blame on climate change for the severity of the current drought in the west, or is this drought relatively typical that better instrumentation precieves as more extreme?