07-04-2023

Study reveals a widespread decline of snow cover in the Northern Hemisphere

Earth.com staff writer

To clarify the magnitude of the ongoing climate crisis, scientists from a variety of fields have recently examined how different climate systems have changed and will continue to change as our planet warms. For instance, by using rigorous mathematical models and statistical methods, a team of researchers led by the University of California Santa Cruz has analyzed snow cover trends in the Northern Hemisphere over the last half a century, and found evidence of declining snow cover in many regions.

Snow plays a major role in the global energy balance, with its high albedo (capacity to reflect light) and insulating characteristics affecting surface temperatures on a regional scale and thermal stability on a larger, continent-wide scale.

Widespread decline in snow cover

To better understand snow cover trends, the experts analyzed data collected from weekly satellite flyovers between 1967 and 2021, which was divided into grid sections. The investigation revealed that snow cover is currently declining in nearly twice as many grids as it is advancing.

“In the Arctic regions, snow is going away more often than not – I think climatologists sort of suspected this,” said study co-author Robert Lund, a professor of Statistics at UC Santa Cruz. “But it’s also going away at the southern boundaries of the continents.”

In an analysis that took nearly four years to complete, the experts found that snow presence in the Arctic and southern latitudes of the Northern Hemisphere is generally decreasing.

Snow cover has increased in some places

However, some regions such as Eastern Canada are experiencing an increase in snow cover, most likely due to rising temperatures in areas that are usually very cold. If temperatures remain below freezing, this phenomenon allows the atmosphere to hold more water, which then falls as snow.

As the researchers stress though, some of the satellite data gathered in mountainous regions proved to be unreliable, showing no snow in the winter. This was probably due to a flow in the algorithm processing satellite data to determine if snow was present or not.

“The reason this study took a lot of work is because the satellite data is so doggone poor,” Lund said. “Whatever the meteorologists did to estimate snow from the pictures in some of the mountainous regions just didn’t work, so we had to take all the grids in the Northern Hemisphere, and figure out whether the data was even trustworthy or not.”

By employing rigorous mathematical and statistical methods to analyze this frequently unreliable data, this study is among the first truly dependable analyses of snow cover trends in the Northern Hemisphere, and could serve as a valuable resource to scientists interested in the effects of climate change on snow cover trends in different areas or time-frames.

The study is published in the Journal of Hydrometeorology.

Why is snow cover important?

Snow cover plays a crucial role in various aspects of the environment and climate. Here are a few reasons why it is important:

Temperature regulation

Snow acts as an insulator, keeping the ground beneath it warmer than it otherwise would be in winter. This insulation is beneficial for plants, insects, and other organisms that overwinter in the soil.

Hydrological cycle

Snow is an essential part of the world’s water supply. As snow melts in the spring, it recharges rivers, reservoirs, and groundwater supplies, providing essential water for drinking, irrigation, and energy production.

Climate impact

Snow’s high albedo (its reflectivity to sunlight) helps regulate Earth’s climate. It reflects most of the sunlight back to space, thereby cooling the planet. When snow cover decreases, the Earth absorbs more sunlight, which can accelerate global warming.

Habitat

Many animals depend on snow cover for survival. For instance, certain species hibernate beneath the snow, which offers them protection from predators and harsh winter temperatures.

Nutrient cycling

Snow can absorb chemicals and other atmospheric particles as it falls, then slowly release them into the soil as it melts, contributing to nutrient cycling and soil fertility.