The Drought of 2013-14 and Climate Change as of February 2014
By Stellar Snow
Running up the hillside, nearing the crest of the ridge, it was clear that it was very dry- more like summer or early autumn than January. The last time such unseasonable dryness was observed in the Rogue Valley was 1977- 37 years ago. Prior to the 1976-77 wet season, such persistent dryness in the wet season (calculated from October 1st onward) had only been recorded in Ashland in 1960 and never before in Medford and Grants Pass, going back to the 1910s. International Airport the month of September ranked 2nd wettest on record. This helped fire crews gain the upper hand on fires in the area, diminishing the smoke and improving the air quality across the region. Spring through autumn of 2013 had the most lightning ever recorded by the Northwest Interagency Coordination Center (NWCC), with records going back through the year 2000. In fact, the number of lightning strikes recorded in 2013 were double the annual average from 2000-2012.
2013 was truly a remarkable year for weather, which comprises climate, in our region and elsewhere on Earth. Climate records clearly indicate that the Earth has generally been warming as CO2 has continued to increase. This warming has accelerated since the late 1970s, as has global CO2 output from anthropogenic sources. Our local extremes in 2013 are clearly consistent with predictions from climate change scientists and climate models, as can be read in the IPCC’s Fifth Assessment. Extreme weather such as has been observed in 2013 puts increasing stress on our biota, to include humans, as we and other species are forced to adapt to survive and thrive. This stress can diminish survivability of some species and favor others, some of which may be invasive. Thus, as we move forward and our climate continues to react to the build-up of CO2 in our atmosphere, we are going to need to do increasingly more to adapt.
In our next post: December 2013’s record cold in portions of the Rogue Valley was also, indeed, exceptional. This will be discussed along with our ongoing snow drought and “Arctic Amplification”.
Fire potential and fire spread potential were high as temperatures climbed into the 60s and southeast winds gusted. Little did we know that the very next morning a 20 acre fire would be found and extinguished by fire crews in the Ashland watershed along the 2060 Road. This was one of a handful of unusual January fires that flared up and spread across portions of western Oregon that January 23rd day. Meanwhile, the Mount Ashland Ski Area, with its base area at 6,338 feet, still did not have enough snow to operate and Mount Shasta, with its peak at 14,162 feet, had little more than its glaciers for snowpack. These conditions, observed in the latter part of January 2013, are just part of a recent trend toward more extreme weather that has been predicted by climate change scientists. Let’s take a closer look at 2013.
2013 was the driest year on record for much of southern Oregon and northern and central California:
Reliable climate records go back to the 1890s to 1910s. Comparing current years to those in the historic climate record gives us a good idea of how years rank in reference to others and can provide clues as to how climate is changing. For some more northern locations such as Ashland, 2013 ranked second driest to 1959. As depicted in the graphic, below, the 2013 drought conditions were both more widespread and more severe than in 1959:
Extreme dryness, however, was not the only remarkable weather and climate fact of 2013. The summer of 2013 had the warmest overnight low temperatures on record at the Medford Airport in the Rogue Valley with an average summer low of 58.9F. Grants Pass also broke the same record. This broke the old record for warmest summer low temperatures in Medford, last set in 2004, by 1.2F. It was so warm at night, on average, that the average of all the highs and the lows for the summer tied for the warmest average summer temperature on record even though the highs were not actually remarkably hot relative to other years. The average high of 90.6F in the summer of 2013 was still well above the long term average of 88.2F in Medford. The average temperature in Medford ended up as 74.8F, tying the old record of 74.8F, previously set in 1967.
Related to the record highest low temperatures for the summer, according to official records taken at the Rogue Valley International Airport in Medford, the 2013 growing season was the longest on record at 241 days. This was computed by counting the number of days from the last 32F or lower temperature of the spring and the first 32F or lower temperature of the autumn. The previous record was set the preceding year, in 2012 at 230 days. This is indeed remarkable- the two longest stretches with temperatures not hitting 32F or lower have now occurred in consecutive years at the Medford Airport. It should be noted that, in Medford, this record could be partially due to urban heat island effects because, while growing seasons have been trending longer in Grants Pass and Ashland, they have not done so as extremely as they have in Medford. For now, these warmer nights have helped increase crop yields and have lengthened the period of harvest for many crops. Conversely, a longer growing season generally results in more water usage. This could become a negative factor in a drought such as the one we are in should we run into water shortages in the later summer and fall.
The cool nights we are used to in the summer in the Rogue Valley allow us to cool our homes during heat waves by strategically opening our windows at night and closing them in the morning after sunrise. Studies have indicated that heat related illnesses and deaths usually result from prolonged exposure to heat, when people cannot cool themselves off. See for details. While it still has generally been cool enough at night for us to do this, warmer overnights this past summer caused many to use air conditioners and fans more often than usual at night in order to catch a break from the heat. This increased use of air conditioners and fans was also driven by severe wildfire smoke.
Wildfires are no stranger to this region. Conditions that cause them to be problematic for firefighting efforts often mount over the course of many days, months, and even years. The steep, complex topography and summer dry season play a major part in most problematic wildfires in our region. This, in combination with sufficient vegetative fuel load and dryness, are the primary preexisting conditions that lead to large fires. For the 2013 fire season, vegetative fuel load was especially high and dry for two reasons: 1) 2012 ranked 7th wettest on record per records at the Medford Airport and, 2) When unusual dryness set in early in 2013 this led to an early snowmelt and early green-up. This early green-up then caused vegetation to dry out faster. The 2012 wetness, along with widespread fire suppression efforts of the last several decades, have collectively caused fuels to build up in our forests. This set the stage for problematic lightning fires for the Oregon Department of Forestry in May and for multiple land management entities in July and August 2013. For more information on the 2013 fire season in Oregon, see:
The wildfire smoke of July to early August 2013 was so severe across most of southern Oregon and neighboring counties of northern California that it was recommended that people stay indoors only where air was sufficiently filtered of particulates for a period of 1-2 weeks. Outdoor events such as the Britt and Shakespeare Festivals were cancelled because of the officially “Unhealthy” air quality. Some even left the area altogether to escape the harmful air. This wildfire smoke was the culmination of the preceding extreme weather.
Luckily, a very unusually wet September followed an increasingly wet August. At the Medford Rogue Valley