observation

The Threat From Thwaites | Earth Wise

January 20, 2022 By EarthWise Leave a Comment

The Thwaites Glacier in Antarctica is the widest glacier in the world. It is about 80 miles across and in places extends to a depth of about 2,600 to 3,900 feet. The glacier is roughly the size of Florida, and it currently contributes 4% of annual global sea level rise as it continues to retreat from a warming ocean.

The International Thwaites Glacier Collaboration is a team of nearly 100 scientists dedicated to studying the glacier. According to the scientists, Thwaites has doubled its outflow speed within the last 30 years. The glacier in its entirety holds enough water to raise global sea levels by over two feet, which would be catastrophic.

A third of the glacier flows more slowly than the rest because it is braced by a floating ice shelf that is held in place by an underwater mountain. The concern is that the brace of ice slowing the glacier may not last for long.

Beneath the surface, warmer ocean water is attacking the glacier from all angles. The water is melting the ice directly beneath the glacier causing it to lose its grip on the underwater mountain. Massive fractures have formed and are growing.

Warm water is also a threat for what is called the grounding zone, which is the area where the glacier lifts off the seabed. There are many possible scenarios under which there could be a major ice loss from the glacier. It is unclear how quickly it could occur. It might take decades, or it could be centuries. The threat is large enough and real enough that continued observation and research is essential.

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The Threat from Thwaites: The Retreat of Antarctica’s Riskiest Glacier

Photo, posted October 16, 2012, courtesy of J. Yungel / NASA Ice via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Shrinking Ice In The Bering Sea | Earth Wise

October 19, 2020 By EarthWise Leave a Comment

The Bering Sea forms the divide between the two largest landmasses on Earth: Eurasia and the Americas. Recent analysis of vegetation from a Bering Sea island has determined that the extent of sea ice in the region is the lowest it has been for over 5,000 years.

St. Matthew Island, a small island in the middle of the Bering Sea, has essentially been recording what is happening in the ocean and atmosphere around it, in the form of the composition of peat layers on the island. By analyzing the chemical composition of peat core samples, scientists can estimate how sea ice in the region has changed over the course of time.

Changes in the relative amounts of two oxygen isotopes in the sediment and plant debris trapped in the peat on the island reflect the nature of precipitation during the period when the peat layers formed. That ratio is correlated with the amount of sea ice in the region. Satellite data acquired over the past 40 years confirms this correlation.

Analysis of the data shows that the current ice levels are unprecedented in the last 5,500 years. These long-term findings affirm that reductions in Bering Sea ice are due to more than recent higher temperatures associated with global warming. Atmospheric and ocean currents, which have also been altered by climate change, play a large role in the presence of sea ice.

Summertime sea ice in the Arctic was expected to reach its second-lowest extent in September in 40 years of observation. Sea ice typically builds up again each winter, but the changes in ice extents actually lag behind changes in greenhouse gas level by decades. Future ice loss is already built into the system.

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Bering Sea ice extent is at most reduced state in last 5,500 years

Photo, posted December 2, 2012, courtesy of Bering Land Bridge National Preserve via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Permanent Time Observation | Earth Wise

September 25, 2020 By EarthWise Leave a Comment

Americans have debated the value of daylight savings time going all the way back to Benjamin Franklin. As a country, we adopted the practice of changing our clocks twice a year in 1918.

Since the energy crisis of the 1970s, there have been a number of initiatives aimed at making daylight savings time permanent. However, there is also a growing movement to eliminate the practice entirely.

In August, the American Academy of Sleep Medicine published a position statement calling for the abolishing of daylight savings time in favor of fixed, national, year-round standard time.

The statement describes the adverse effects of the annual abrupt switch to daylight savings time, which range from increased risk of stroke and hospital admissions to sleep loss and increased production of inflammatory markers, which are one of the body’s responses to stress. It also cites studies that show that traffic fatalities increase by as much as six percent in the first few days following the change to daylight savings time. Other research shows that there is an 18% increase in adverse medical events related to human error in the week after switching to daylight savings time.

In July, a survey by the academy of more than 2,000 U.S. adults found that 63% support the elimination of seasonal time changes in favor of a national, fixed year-round time, and only 11% oppose the idea, but many of those in favor of the idea actually want permanent daylight savings time.

The sleep academy contends that permanent standard time is the best choice to most closely match our circadian sleep-wake cycle while daylight saving time results in more darkness in the morning and more light in the evening, disrupting the body’s natural rhythm.

Residents of Arizona and Hawaii get to sit out this debate since they don’t change their clocks.

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American Academy of Sleep Medicine calls for elimination of daylight saving time

Photo, posted May 28, 2018, courtesy of Kis Akos via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.