High-elevation data showing warming trends in the Western United States over a period beginning in the mid-1990s are likely inaccurate, according to the Daily Inter Lake. A study looking into temperature sensors used to take the measurements has found the devices to be biased by about 1.5 degrees Celsius.
The sensors were installed as part of the U.S. Department of Agriculture’s SNOTEL monitoring system, also known as the Snowpack Telemetry station network. They were integrated into more than 700 weather stations that constitute the system.
“What happened was the new sensor was biased relative to the old one, causing an apparent increase in temperatures across the whole network,” said Jared Oyler, a researcher at Montana State University’s Climate Office who uncovered the discrepancy, to the Daily Inter Lake. “It was a really big error … (that) showed about a degree celsius rise per decade, which is very large concerning trends.”
The problem of faulty sensors is isolated to the SNOTEL network, Oyler says, and only affects the period during which they were installed. Oyler has revised the temperature data to remove the sensor bias, and they show that temperatures still rose but not by as much as had been reported before. Data on snowpack levels aren’t impacted by the biased temperature sensors because they rely on different measuring devices.
Top image: Temperature data from high-altitude sensors found to be inaccurate. (Credit: Jaix Chaix, via Wikimedia Commons/CC BY 2.0)