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Shrinking polar ice

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Arctic sea ice has shrunk to near-historic lows during this Northern Hemisphere summer.  The minimum extent for the year occurred on September 11th.  Ice cover in the Arctic Ocean has been shrinking and thinning for more than 40 years.  The amount of frozen seawater in the Arctic goes up and down during the year as sea ice thaws and regrows between seasons.

This year, the minimal extent of sea ice shrank to 1.65 million square miles.  That’s about 750,000 square miles less than the average for late summer over the years between 1981 and 2010, representing a decrease of more than 30%.  The all-time low of 1.31 million square miles was actually set in 2012.  Sea ice coverage can fluctuate from year to year, but it has trended downward since it has started being tracked in the late 1970s.  The loss of sea ice has averaged about 30,000 square miles per year.

Sea ice extent has not only been shrinking; the ice has been getting younger and thinner.  Presently, the overwhelming majority of ice in the Arctic Ocean is first-year ice, which is thinner and less able to survive the warmer months.  There is far less ice that is three years or older.

Meanwhile, sea ice in the southern polar regions was also low this year.  In the sea around Antarctica, scientists are tracking near record-low sea ice at a time when it should have been growing extensively during the darkest and coldest months in the Southern Hemisphere.

Polar ice loss compounds polar ice loss.  The loss of sea ice increases heat in the polar regions, where temperatures have risen about four times more than the global average.

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Arctic Sea Ice Near Historic Low; Antarctic Ice Continues Decline

Photo, posted September 15, 2016, courtesy of Mario Hoppmann via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Record low Antarctic sea ice

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Antarctica’s winter came to a close in September and during that month, the continent reaches its maximum amount of sea ice that grows during the darkest and coldest months.  This year, that maximum occurred on September 10th and turned out to be the lowest on record.

The sea ice around Antarctica reached a maximum extent of 6.5 million square miles according to NASA researchers.  That was nearly 400,000 square miles below the previous record low set in 1986. 

There are several possible causes for the meager growth of Antarctic sea ice this year.  It may be a combination of several factors including El Niño, wind patterns, and warming ocean temperatures.  Recent research indicates that ocean heat is most likely playing an important role in slowing ice growth in the cold season and enhancing ice melting in the warm season.

The record-low ice extent so far this year is a continuation of a downward trend in Antarctic sea ice that has gone on since the ice reached a record high in 2014.  Prior to that year, the ice surrounding the southern continent was actually increasing slightly by about 1% every decade.

Meanwhile, Arctic sea ice reached its minimum extent in September and it was the sixth-lowest level in the satellite record.  Scientists track the seasonal and annual fluctuations of polar sea ice because they shape polar ecosystems and play a significant role in global climate.  Sea ice melting at both poles reinforces global warming because bright sea ice reflects most of the Sun’s energy back to space while open ocean water absorbs 90% of it.

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Antarctic Sea Ice Sees Record Low Growth  

Photo, posted June 30, 2023, courtesy of Pedro Szekely via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Finding Homes For Rhinos | Earth Wise

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Northern White Rhinos are virtually extinct; only two female individuals survive in Kenya.  Southern White Rhinos also nearly vanished early in the 20th century, mostly because of excessive hunting.   A surviving group of fewer than 100 animals was identified in South Africa, and ongoing conservation efforts led to the existing population of southern white rhinos, which now numbers more than 16,000.

Among the most successful conservation efforts took place at a 30-square-mile farm, Platinum Rhino, that was set up in 2009 about 100 miles southwest of Johannesburg.  The owner of the farm did a great job of maintaining genetic diversity of the herd and protecting it from poachers.  Eventually, it was costing $175,000 a month just for security against illegal hunters seeking rhino horns.

Faced with unsustainable expenses, the farm put the herd of 2,000 rhinos up for auction in April with a starting price of $10 million.  No bidders came forward. 

Fortunately, in September, the conservation group African Parks announced that it had reached a deal to take over the herd.  African Parks partners with 12 countries in Africa to manage 77,000 square miles of protected areas.

The plan is to start moving the rhinos into a series of new sites in the wild starting next year.  Moving the 5,000-pound animals to new locations will be complicated and expensive, costing anywhere from $1,500 to move a single rhino by land within South Africa to $50,000 for far afield air transport.  African Parks is now raising funds to relocate the animals.

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Now Available: 2,000 Rhinos, Free to Good Homes With Plenty of Space

Photo, posted September 4, 2023, courtesy of Eric Huybrechts via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

California Flooding | Earth Wise

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Starting in December, a series of “atmospheric rivers” brought record storms to California producing as much rain in three weeks in some areas as they normally have in an entire year.  The historic levels of rain (and snow in the mountains) have swollen rivers, flooded roads and homes, forced evacuations, knocked out electric power for millions of people, and resulted in more than 20 deaths.

Atmospheric rivers are air currents that carry large amounts of water vapor through the sky.  They are not unusual for California but recurrent waves of them like those that have happened recently are very infrequent.  Studies by the U.S. Geological Survey have shown that such a phenomenon recurs in California every 250 years.  There were a series of storms causing disastrous floods in California in 1861-62.

The atmospheric rivers are born in the warm waters of the tropical Pacific.  During La Nina phases, the atmospheric rivers typically make landfall on the northern West Coast. During El Nino phases, atmospheric rivers are more likely to end up in Southern and Central California. During transitions between the phases, as is happening now, the storms can cover large parts of the state.

Modern forecasting is pretty good at predicting the forthcoming occurrence of these storms and has led to some helpful actions, such as reservoir operators preventing dams from overflowing or bursting.  But there is a gap between science and decision-making.  It is pretty clear what needs to be done when tornados or hurricanes are on the way.  It is less clear what actions are appropriate when there are going to be repeated heavy rainstorms.

These storms will have an effect on California’s megadrought, but just how much of an effect remains to be seen.

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Flooding in California: What Went Wrong, and What Comes Next

Photo, posted January 5, 2023, courtesy of Sarah Stierch via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Wildlife And The Border Wall

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The border between the United States and Mexico is nearly 2,000 miles long, stretching from San Ysidro, California to Brownsville, Texas.  Discontinuous barriers currently cover approximately 650 miles of our southern border. As the particulars of how to better secure the remaining 1,350 miles of border are worked out, one thing is abundantly clear: extending physical barriers would negatively impact wildlife and the environment.

The Trump Administration has called for a 1,000-mile wall, which would cut across land that includes important habitats for wildlife.  According to an article signed by nearly 3,000 scientists, this plan would “threaten some of the continent’s most biologically diverse regions” by inhibiting species movement and triggering flooding. The paper, which was published in the journal Bioscience, highlights how more than 1,500 native animal and plant species would be affected by the wall, including 62 that are listed as endangered or vulnerable.

An extended border wall would not only impede movement of many wildlife species but it would also put pressure on creatures already in peril, such as the Mexican gray wolf and the Sonoran pronghorn.  Other at risk animals include the ocelot, black bear, and desert bighorn sheep. 

According to researchers, extending the border wall could cause problems for low-flying birds and insects. Even plants, including the endangered wildflower Zapata bladderpod and the threatened whiskerbush cactus, are particularly at risk.

According to a 2011 study, bird-watching and other forms of ecotourism in the Lower Rio Grande Valley brought in more than $344 million in economic activity and approximately 4,400 jobs. 

Preserving our natural heritage must be part of this national security discussion. 

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Nature Divided, Scientists United: US–Mexico Border Wall Threatens Biodiversity and Binational Conservation

Photo, posted December 14, 2014, courtesy of Tony Webster via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

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