Fact Checking the Third Assessment Report from the CA Climate Change Center, Part I
08/03/2012 3 Comments
In Part I of this fact checking project, I will start with the section titled California’s Changing Climate. The first sentence set off my alarm bells right away, as I have been studying the climate change in the Sierra since 2004.
Observed changes over the last several decades across the western United States reveal clear signals of climate change. Statewide average temperatures increased by about 1.7°F from 1895 to 2011, and warming has been greatest in the Sierra Nevada.
I have not see any great changes in the Sierra temperatures over the last several decades except at one Lake Tahoe Surface Station. This station neighbors include a tennis court, and for a while a trash burn barrel. More on this site later in the analysis.
There was no indication in the report where the Sierra temperatures were measured. But in previous reports there was a high dependence on the COOP station at Lake Tahoe, as it had the longest record in the basin.
As you can see there was a significant jump in temperature starting around 1980. A jump that is not evident in other sites around Lake Tahoe and the Sierra. Some investigation revealed that 1980 was about the time a concrete tennis court was installed next to the surface station. According to the condo property manager that an investigator spoke to said the court was installed in the “early 80’s”, though she was not there at the time. This tennis court heats up during the day and gives up energy at night, warming the area. According the grounds keeper, he picked up trash during the day and burned it at the end of the shift, leaving a warm burn barrel to increase the night time temperatures.
Starting in the late 1980s the Forest Service started installing remote automated weather stations (RAWS) well way from built up areas with potential heat sources like the Tahoe tennis court. These remote rural sites do not show any significant Sierra warming.
Owens Camp, El Dorado National Forest, near Kyburz was one of this RAWS sites.
There is a modest increase in the night time temperatures and a decline in the day time temperatures, which average out to no average change.
Quincy Ranger Station, Tahoe National Forest, is another RAWS station
As you can see the temperatures vary from year to year, but according to the regression analysis the temperatures are essentially flat for the 19 years examined. It appears that from about 2002 to 2010 the temperatures have been in declining year over year.
There is also a COOP station in Truckee with recored that goes back several decades that is only 15 miles from the Tahoe station.
As you can see there is no significant warming just 15 miles away from the COOP site at Lake Tahoe. No significant jump in 1980.
There you have it, three Sierra sites that do not show any significant warming. So, where did the scientist at the Climate Change Center find the Sierra warming data? If they only used the Tahoe Site, they were fooled by a poorly sited weather station. Real scientist would not use a single site, but look at the whole Sierra. This report appears to be more the work of political hacks than scientists. Here is the lead authors web site: http://www.susannemoser.com/ You decide?