00:49 Snowfall Doubles at Alaska's Tallest Peaks Meteorologist Danielle Banks talks about a new study that's reveals snow accumulation rates are more than doubling at some of Alaksa's tallest peaks.

At a Glance Snowfall in the winter has more than doubled in south-central Alaska since the mid-19th century.

Research suggests that warmer ocean water in the tropics have caused the Aleutian Low to strengthen.

This stronger low pressure has substantially increased snow accumulation in portions of Alaska.

Winter snowfall has more than doubled since the mid-1800s at some of south-central Alaska's highest peaks, according to a new study from Dartmouth College, the University of Maine and the University of New Hampshire.

Since 1840, winter snowfall has increased by 117 percent in south-central Alaska. In addition, snowfall during the summer was also found to have increased by 49 percent during this time period. Winter and summer snowfall was separated by examining markers in ice cores, such as ammonium.

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This increase in snowfall was found by analyzing a 1,200-year ice core record of snow accumulation from Mount Hunter, the third-highest major peak in Alaska Range, located in Denali National Park in south-central Alaska. Mount Hunter's elevation reaches just over 14,500 feet. This analysis used four separate equations to account for ice-thinning in the samples.

This study, published in Scientific Reports , also found that snow accumulation rates from 1950 through 2013 were "the highest of the last 1,200 years " and "far exceeds normal variability."

Erich Osterberg, Assistant Professor of Earth Sciences at Dartmouth College and one of the researchers, noted: "We were shocked when we first saw how much snowfall has increased. 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."

<img class="styles__noscript__2rw2y" src="https://dsx.weather.com/util/image/w/alaska_snow_double_graph.jpg?v=at&w=485&h=273&api=7db9fe61-7414-47b5-9871-e17d87b8b6a0" srcset="https://dsx.weather.com/util/image/w/alaska_snow_double_graph.jpg?v=at&w=485&h=273&api=7db9fe61-7414-47b5-9871-e17d87b8b6a0 400w, https://dsx.weather.com/util/image/w/alaska_snow_double_graph.jpg?v=ap&w=980&h=551&api=7db9fe61-7414-47b5-9871-e17d87b8b6a0 800w" > Time series shows the dramatic doubling of snowfall around North America's highest peaks since the beginning of the Industrial Age. Inset shows summer (red) and winter (blue) snowfall since 1870. (Figure provided by Dominic Winski) (Figure provided by Dominic Winski)

Given these surprising findings, the next step was to determine why this was observed.

Although temperatures in central Alaska have increased since the mid-20th century, which would likely bring an increase in precipitation since warmer air can hold more moisture, it does not account for the amount of snowfall increase found.

The researchers did find that the change in snowfall coincides with the increase in sea-surface water temperatures that has been taking place in the western tropical Pacific Ocean and the Indian Ocean, which has been linked to higher greenhouse gas concentrations.

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More specifically, the study found that the observed increases in winter and summer snowfall were due to a long-term strengthening of the Aleutian Low. Earlier research found that the most likely way to intensify the Aleutian Low is with warmer tropical sea-surface temperatures.

Precipitation in the northern Pacific is strongly influenced by the strength of the Aleutian Low , named for its proximity to the Aleutian Islands in the Gulf of Alaska from late fall to late spring. When the Aleutian Low is strong, the result is more precipitation along the southern Alaska coast , according to a study published in the Journal of Geophysical Research in 2004.

This new study builds on recent research that showed "an intensification of winter storm activity in Alaska and Northwestern Canada, driven by the strengthening Aleutian Low, started in 1740 and is unprecedented in magnitude and duration over the past millennium."

<img class="styles__noscript__2rw2y" src="https://dsx.weather.com/util/image/w/ice-core-photo.jpg?v=at&w=485&h=273&api=7db9fe61-7414-47b5-9871-e17d87b8b6a0" srcset="https://dsx.weather.com/util/image/w/ice-core-photo.jpg?v=at&w=485&h=273&api=7db9fe61-7414-47b5-9871-e17d87b8b6a0 400w, https://dsx.weather.com/util/image/w/ice-core-photo.jpg?v=ap&w=980&h=551&api=7db9fe61-7414-47b5-9871-e17d87b8b6a0 800w" > Earth's climate history is in our hands. Ice core segments like this from Mount Hunter in Alaska's Denali National Park were used to discover a doubling of snowfall in south-central Alaska. This photo is actually the very bottom of an ice core segment, just above bedrock. The ice used in the study is from higher up in the core because the ice at the base of the glacier is very difficult to interpret. (Bradley Markle) (Bradley Markle)

The study notes that with a deeper Aleutian Low, the largest precipitation increases would be expected to occur where southerly flow on the eastern side of the low encounters the Alaskan coastline and mountain ranges.

The results of this new research correspond with this expectation.

"This is exactly the pattern we observe , with increasing precipitation at coastal Alaskan weather stations including Kodiak, Juneau and Valdez, and the strongest precipitation increases at orographic barriers such as Mount Hunter and Aurora Peak," the study said.

In addition, the increase in water temperature in the tropical Pacific and Indian Oceans and the corresponding response from the atmosphere would also suggest a reduction in precipitation in Hawaii, due to the anomalously high pressure in the subtropical North Pacific, which is the case.

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This study is also an example of how climate change can impact the circulation in the atmosphere, which can bring significant changes in regional precipitation.

This doubling of snowfall on Mount Hunter demonstrates how warmer temperatures can have significant regional impacts. Osterberg commented that "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. 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."

One other note from the researchers: changes to climate models are needed to improve rainfall and snowfall predictions due to the current underestimation of the sensitivity of the North Pacific atmospheric connections to the warming sea surface temperatures.