Earth just experienced the warmest winter on record. Temperatures for December–February beat the previous winter record in 2007 by 0.05 degrees, NOAA's National Climatic Data Center reported. Global temperature records go back to 1880. The State of Oregon, where Mount Hood's Sandy Glacier, experienced it's second warmest winter in 2014 and 2015.
The Sandy Glacier on Mount Hood has a system of glacial ice caves that have responded to this unprecedented heat. Ice caves are temporary, but the Snow Dragon cave's roof collapsed highlighting the rapid melting process that can be seen from below the glacier.
Glacier Hub reports:
This was always a fate for the ice cave that could have been anticipated. For years, many climbers have said Snow Dragon and other cave systems like it would melt before long. Ice thawing from within the glaciers forms the caves. As that thawing continues and expands outwards, it begins to breach the surface. Once tunnels open to the surface, the glaciers continue to melt in an increasing positive feedback: warm surface air travels down the tunnels to the glacier’s core, increasing the rate of melt and creating new surface openings.
Brent McGregor and Eddy Cartaya have been documenting the caves since 2011. Check out their
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Moulins and caves are normal features in glaciers. They compose the drainage system for rivers of ice. Outdoor Project elaborates:
Glaciologists have found that large glacial caves such as these only occur in thin, dying glaciers, whereas caves that form in larger and thicker glaciers quickly collapse under their own weight. Because the peaks of the Cascade Range lie in relatively warm climates (as opposed to Alaska, for instance), surface friction alone is often enough to introduce some melting. Once a channel of water is formed, its size will only increase over time as more water passes through. Additionally, the caves allow warm air to enter deep into the glacier, ensuring an even quicker melting process.
The process is not without precedent: The Paradise Glacier Caves on Mount Rainier's south side were once a major attraction to the national park. By the 1970s, however, the ceiling began to collapse. Today, the caves are long gone, and the lower portion of the glacier no longer exists.
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