Scientists Link Melting Sea Ice and Ice Shelf Calving to Climate Change
Plus Zebra Mussels, Women Cyclists, Bird Conservation, the Greater Sage-Grouse, the Middle Huron River, ESA Listings, Colorado Fracking, and Clearcutting Near Yellowstone
This week we turn our attention to the poles and some of the new scientific findings at the ends of the earth.
Hurricanes and cyclones are associated with subtropical regions of the world, whipping against Florida or crashing through the South China Sea. Cyclones form in polar regions as well, and scientists have noted that they have increased in frequency over the last 50 years. This increase in the number of polar cyclones has been predicted by scientists, with ramifications for the Arctic, Antarctic, and the rest of the world as well.
Due to global warming, polar sea ice has retreated over the last 50 years, which has accelerated in the last decade. The common assumption has been that warmer air over the sea and ice melts the ice, but some recent research finds other factors are at play.
Polar cyclones reduce sea ice
In August of 2016, a South Korean icebreaker got caught in an Arctic cyclone. Though the experience must have been nerve-wracking, scientists on the ship took the unique opportunity to gather data from inside the storm.
A team of researchers examined the data and found that sea ice receded 5.7 times faster than normal during the storm. The team published their findings in Geophysical Research Letters, a peer-reviewed journal of the American Geophysical Union.
Warm air was less a factor in the sea ice melt than the strong winds that pushed water away from the cyclone, causing upwelling of warmer water from below. The cyclone also mixed the warmer and colder water. The mixing and upwelling warmed the entire upper level of ocean water, thus melting the sea ice.
The melting sets up a feedback loop. The cyclones clear large areas of water from around the ice. The water has a higher albedo than the sea ice, which means that it absorbs more solar radiation and warms more than the ice. And that warmer water melts even more sea ice. More warming = more cyclones = more open water free of sea ice = more absorbed solar radiation = more warming, etc.
Ice shelf calving linked to global warming
In 2019, a very large section of the Amery Ice Shelf calved, the largest calving since 1963, when an even larger iceberg broke away from the shelf. Though calving of polar ice shelves is a natural occurrence and happens all the time, this calving surprised scientists, who did not expect this portion of ice to break off from the shelf for another ten years.
Several Antarctic ice shelves have collapsed in recent years, leading scientists to take an increased interest in them. A scientific team whose academic affiliations spread across the world, from the United Arab Emirates, the Netherlands, the U.S., and Australia, has linked the 2019 calving event with global warming.
In this case, a series of powerful twin polar cyclones over seas adjacent to the Amery Ice Shelf created tides and upwelling of water levels, which led to the weakening of a pre-existing rift and the subsequent calving. As mentioned above, the increasing number of these cyclones has been linked to climate change, and still more of these intense storms are expected.
Ice shelves develop when polar glaciers meet the sea. Glaciers push the ice out into the sea, where it floats on the water. Ice shelves are usually from 300 to 3000 feet thick and are only found in Antarctica, Greenland, Canada, and northern Russia.
The Amery Ice Shelf is the third largest in Antarctica. Although it takes up a small portion of the Antarctic coastline, the Amery drains about 16 percent of the East Antarctic Ice Sheet. The calved section of the shelf was 632 square miles, about half the size of Long Island.
Ice shelves are constantly accumulating mass as the glaciers push their ice seaward. The accumulation is balanced by calving, when large chunks of the shelf break off and drift into the sea. Many ice shelves may be shrinking due to increased calving caused by global warming.
Because sea ice floats, increased calving, in and of itself, will not lead to sea level rise. But just as a clog in a garden hose decreases the flow of water from the nozzle, ice shelves slow the flow of glaciers to the sea. Shrinking ice shelves mean more glacial ice moves from land to ocean, thus raising sea levels.
Explosive cyclones are more intense and last longer than ordinary cyclones. They are more prevalent in the Southern Hemisphere than in the Northern Hemisphere. A study of these more powerful cyclones found that they increased in both hemispheres from 1979 through 1999. Another study, over a longer period of time, found similar results. Additionally, these cyclones are shifting poleward, resulting in an increase in the number and intensity of explosive cyclones around the Antarctic.
An extreme situation is the formation of twin cyclones, which feed off each other, making each one twice as strong. The scientists note that explosive twin cyclones have only been observed in the tropics, mid-latitudes, and Arctic. The scientists believe that the two twin cyclones described in their study may be the first to be studied in the Antarctic.
In this case, the first explosive cyclone developed on September 18, 2019, and further developed into two stationary twin polar cyclones that sat to the west of the Amery Ice Shelf on September 19-22. On September 23, the second explosive cyclone developed, turning into twin polar cyclones on September 24-25. These cyclones were positioned to the east of the ice shelf.
Both of the events brought in warm moist air from the north, as well as storm surges and other ocean and weather conditions that put a strain on the ice shelf, which led to the calving. More explosive cyclones and the formation of twin cyclones may be expected to lead to additional large calving of the Antarctic ice shelves.
Invasive zebra mussels found in pet stores
A nationwide alert has found zebra mussels in pet stores in 21 states. A citizen’s report prompted the search for the invasive and destructive shellfish. Ornamental moss balls, sold in pet stores for aquariums, have been found to be the culprit. Many of the moss balls contain the mussels and may have inadvertently spread them to states where they have not been found before. The pet stores are cooperating with state and federal agencies to remove the moss balls from their shelves. (USGS)
From the Obviously Obvious Department: More women on bikes = more people on bikes
In a travel survey of 11 countries, researchers found that cities that catered to the needs of women cyclists have a higher rate of cycling overall. (Streetsblog USA)
New study of bird conservation and climate change in the Americas
Although many bird species are migrating to new territories, this study found that conservation of these species is still possible. (Audubon)
The Biden Administration resumes help for the greater sage-grouse
The Trump administration had sidelined efforts to conserve habitat and populations of the greater sage-grouse. The Bureau of Land Management (BLM), under Joe Biden, has restored plans for the conservation of this North American bird. (Audubon)
Huron River Watershed Council and stakeholders compile best management practices for the Middle Huron River
The recommendations are to be incorporated into the greater water management plan to mitigate impairments to the section of the Huron River that is adjacent to and flows through Ann Arbor, Michigan. (Huron River Watershed Council)
U.S. Fish and Wildlife Service announces Endangered Species Act assessments for three species
On the eleventh of this month, the USFS announced 90-day findings on petitions to list three species under the Endangered Species Act:
Aztec gilia (Aliciella formosa): A member of the phlox family that is only found in the northwest corner of New Mexico, this small perennial with pink flowers is threatened by oil and gas drilling, off-road vehicles, livestock grazing, and climate change.
Clover's cactus (Sclerocactus cloverae): The same human activities, along with poaching, threaten this New Mexican cactus.
Suckley's cuckoo bumblebee (Bombus suckleyi): This bee is found from New York State through much of Canada and Alaska. It is also found in the Great Plains and western states. Habitat loss, disease, loss of hosts, pesticides, climate change, and loss of genetic diversity are thought to be factors in the insect’s decline.
To perform the status reviews, the agency is requesting scientific and commercial information on the three species. (U.S. Fish and Wildlife Service)
Lawsuit from conservation groups challenges BLM approval of fracking on Colorado’s Western Slope
The BLM approved a plan allowing for 35 new fracking wells across 35,000 acres of three National Forests. The lawsuit, from the Western Environmental Law Center, the Center for Biological Diversity, Citizens for a Healthy Community, and others, claims that federal agencies violated the National Environmental Policy Act by not fully assessing the potential for water pollution and greenhouse gas emissions when they approved the plan. (Center for Biological Diversity)
Forest Service halts planned clearcutting next to Yellowstone
This week the Forest Service halted plans to clearcut more than 4,600 acres of pine forest, log an additional 9,000 acres, and create up to 56 miles of roads on lands adjacent to Yellowstone National Park.
In court, the Center for Biological Diversity and other environmental organizations challenged the plans, citing the destruction of habitat for grizzly bears, wolverines, lynx, and pine martens. The plans also did not accurately describe where or when the bulldozing of the roads or clearcutting would occur, violating the National Environmental Policy Act. (Center for Biological Diversity)
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