Snowfall on a major summit in North America’s highest mountain range has more than doubled since the beginning of the Industrial Age, according to a study from Dartmouth College, the University of Maine and the University of New Hampshire.
“Everywhere we look in the North Pacific, we’re seeing this same fingerprint from warming tropical oceans. One result is that wintertime climate in the North Pacific is very different than it was 200 years ago. This doesn’t just affect Alaska, but Hawaii and the entire Pacific Northwest are impacted as well,” said Dominic Winski, a research assistant at Dartmouth and the lead author of the report.
The research not only finds a dramatic increase in snowfall, it further explains connections in the global climate system by attributing the record accumulation to warmer waters thousands of miles away in the tropical Pacific and Indian Oceans.
The research demonstrates that modern snowfall in the iconic Alaska Range is unprecedented for at least the past 1200 years and far exceeds normal variability.
“We were shocked when we first saw how much snowfall has increased,” said Erich Osterberg, an assistant professor of earth sciences at Dartmouth College and principal investigator for the research. “We had to check and double-check our results to make sure of the findings. Dramatic increases in temperature and air pollution in modern times have been well established in science, but now we’re also seeing dramatic increases in regional precipitation with climate change.”
According to the research, wintertime snowfall has increased 117 percent since the mid-19th century in south-central Alaska. Summer snows also showed a significant increase of 49 percent in the short period ranging less than 200 years.
The researchers note that the findings imply that regions that are sensitive to warming tropical ocean waters may continue to experience rain and snowfall variability well outside the natural range of the past millennium.
The research is based on analysis of two ice cores collected at 13,000 feet from Mount Hunter in Denali National Park. According to the authors, accumulation records in the separate samples taken from just below the summit of the mountain known as “Denali’s Child” are in nearly complete agreement.
“Climate change can impact specific regions in much more extreme ways than global averages indicate because of unexpected responses from features like the Aleutian Low,” Osterberg said. “The Mount Hunter record captures the dramatic changes that can occur when you get a double whammy from climate change — warming air combined with more storms from warming ocean temperatures.”
“It is now glaringly clear from our ice core record that modern snowfall rates in Alaska are much higher than natural rates before the Industrial Revolution,” Winski said. “This increase in precipitation is also apparent in weather station data from the past 50 years, but ice cores show the scale of the change well above natural conditions.”