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Disappearing Glaciers | Earth Wise

February 20, 2023 By EarthWise Leave a Comment

Glaciers are massive bodies of slowly moving ice. Glaciers form on land, and represent the snows of centuries compressed over time. They move slowly downward under the influence of their own weight and gravity.

Most of the glaciers on the planet are found in the polar regions, including Antarctica, the Canadian Arctic, and Greenland. Glaciers can also be found closer to the equator in mountain ranges, such as the Andes Mountain range in South America. Glaciers are always changing, accumulating snow in the winter and losing ice to melting in the summer. But in recent times, the melting has been outpacing the accumulation.

A new international study led by researchers at Carnegie Mellon University’s College of Engineering has produced new projections of glacier loss through the century under different emissions scenarios. According to the projections, the world could lose as much as 41% of its total glacier mass this century – or as little as 26% – depending on climate change mitigation efforts.

In a future with continued investments in fossil fuels (sometimes referred to as the “business as usual” scenario), more than 40% of the glacial mass will be gone by 2100, and more than 80% of glaciers by number could disappear. Even in a best case scenario where the increase in global mean temperature is limited to 1.5° degrees Celsius relative to pre-industrial levels, more than 25% of glacial mass will be gone, and nearly 50% of glaciers by number will disappear.

Glaciers take a long time to respond to changes in climate. A complete halt to emissions today would take anywhere from 30 to 100 years to be reflected in glacier mass loss rates.

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Team projects two out of three glaciers could be lost by 2100

Ice, Snow, and Glaciers and the Water Cycle

Photo, posted August 13, 2010, courtesy of Kimberly Vardeman via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Fire And Ice | Earth Wise

January 17, 2022 By EarthWise Leave a Comment

In recent years, there have been countless stories about the effects of the changing climate. Many of those stories have been about the dwindling sea ice in the Arctic and many others have been about the worsening wildfires in the western United States. According to a recent study published by the Pacific Northwest National Laboratory, those two things are very much related.

As sea ice in the Arctic melts from July to October, sunlight warms the surrounding land and sea surfaces. The resulting differences in air pressure create and strengthens a vortex in the atmosphere above the heated area which spins counterclockwise like a cyclone.

The powerful vortex pushes the polar jet stream out of its typical pattern and diverts moist air away from the western United States. With the jet stream moved off its usual course, a second vortex, this time spinning clockwise, forms under the ridge of the polar jet stream above the Western U.S. This second vortex brings with it clear skies and dry conditions: fire-favorable weather.

Arctic sea ice has continually declined at least since the late 1970s. It is predicted that there will be periods of entirely iceless Arctic waters before the 2050s. In turn, conditions in the already fire-ravaged West are likely to be further exacerbated. More than three million acres have burned across California alone during the 2021 wildfire season.

Climate conditions in one part of the world can, over time, influence climate outcomes thousands of miles away. The research at Pacific Northwest Laboratory reveals how regional land and sea surface warming caused by Arctic ice melting can trigger hotter and drier conditions in the West later in the year.

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Fire and Ice: The Puzzling Link Between Western Wildfires and Arctic Sea Ice

Photo, posted July 28, 2018, courtesy of Bob Dass via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

More Carbon Dioxide From Thawing Permafrost | Earth Wise

July 30, 2020 By EarthWise Leave a Comment

The Arctic is warming much faster than the rest of the planet. Stories about the loss of polar ice and hundred-degree temperatures in Siberia have become commonplace. One of the most troubling aspects of the warming Arctic is the thawing of permafrost. Permafrost is ground that remains frozen for at least two years; some of it has been frozen for tens or hundreds or even thousands of years. Found under a layer of soil, permafrost is composed of rock, soil, sediments, and varying amounts of ice. It stores the carbon-based remains of plants and animals that froze before they could decompose. Permafrost covers almost a quarter of North America, but it is starting to thaw.

Scientists estimate that there are more than 16,000 billion tons of carbon locked away in Arctic permafrost, which is almost double the amount of carbon that is currently in the atmosphere. Climate models predict that the warming of the Arctic could lead to 5 to 15% of that carbon to be emitted as carbon dioxide by the year 2,100, which would be enough to raise global temperatures by 0.3 to 0.4 degrees Celsius.

New research has increased this estimate because it includes a key pathway for CO2 to enter the atmosphere that earlier models ignored. When carbon from thawing permafrost escapes into Arctic lakes and rivers, it is oxidized by ultraviolet and visible light and it then escapes into the atmosphere as CO2. This process is known as photomineralization and is estimated to raise permafrost-related CO2 emissions by 14%.

Recent studies project that with every 1-degree Celsius increase in temperature, 1.5 million square miles of permafrost could be lost through thawing.

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Climate Models Underestimate CO2 Emissions from Permafrost by 14 Percent, Study Finds

Photo, posted July 7, 2014, courtesy of NPS Climate Change via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

An Ecological Trap For Polar Bears | Earth Wise

March 17, 2020 By EarthWise Leave a Comment

Climate change has been shrinking Arctic sea ice and this is causing changes in the behavior of polar bears. The Southern Beaufort Sea, located where the northern edges of Alaska and Canada meet, is home to one of the 19 population groups of polar bears. Historically, the polar bears in this region remained on sea ice year-round. But in recent decades, about a quarter of them have chosen to come on land instead of staying on the shrinking summer ice platform.

A recent study by San Diego Zoo Global, the U.S. Geological Survey, and Polar Bears International looked at the energetic consequences of the bears’ behavior. The decision of each individual bear to stay on the ice or move to land appears to be linked to the energetic cost or benefit of the choice.

Bears who moved to land expended more energy during the summer than bears that remained on the sea ice. In late summer, as the ice became even more restricted, a greater amount of energy was expended by bears swimming to land. So, the immediate energy cost of moving to land is much greater than remaining on the receding pack ice.

On the other hand, bears on land in this region have access to whale carcasses in the summer while bears on the sea ice appear to be fasting. As a result, it may be the case that the declining population of bears in this region is in part caused by the ecological trap of bears staying on the ice to avoid expending all the energy needed to move to land. The shrinking polar ice is a real problem for polar bears.

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