expands

Sea levels are rising and ocean warming is responsible for the bulk of that rise. As water heats up, it expands, which drives up sea levels. But on top of that, global warming is melting the polar ice sheets, and that is leading to about a quarter of the world’s sea level rise. So far, polar melting has fueled about an inch of sea level rise, two-thirds from Greenland and one third from Antarctica. According to scientists, by the end of this century, melting polar ice caps could raise sea levels between 6 and 10 inches.

The seven worst years for polar ice sheet melting have occurred during the past decade. The worst year on record was 2019. The loss in 2019 was driven by an Arctic summer heatwave, which resulted in record melting from Greenland, amounting to nearly 500 billion tons melted that year. Antarctica lost 180 billion tons of ice that year, mostly due to melting glaciers and record melting from the Antarctic Peninsula.

Ice losses from Greenland and Antarctica can now be reliably measured by satellites in space. A team of researchers led by Northumbria University in the UK has combined 50 satellite surveys taken between 1992 and 2020.

They have found that the Earth’s polar ice sheets have lost over 8,000 billion tons of ice over that time period. That much ice corresponds to an ice cube roughly 12 miles high.

The satellite technology is now at the stage where the ice sheet status can be continuously updated. Such monitoring is critical to predict the future behavior of the ice sheets and provide risk warnings of the dangers that coastal communities around the world will face.

**********

Web Links

Polar ice sheet melting records have toppled during the past decade

Photo, posted December 19, 2017, courtesy of Jasmine Nears via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Global sea level rose by about 6 inches during the 20th century. It is currently rising more than twice as fast and accelerating. The rate of rise was 2.5 times faster from 2006 to 2016 than it was for nearly all of the 20th century.

Sea level rise occurs when glaciers and ice sheets lose mass. Much of that meltwater comes from Greenland and Antarctica. But levels also rise because, as water warms, it expands. Added to that are the effects of human activities such as groundwater depletion and a geological phenomenon called isostatic adjustment that is going on in parts of the East Coast where the land is actually sinking.

In Atlantic Canada, sea level rise is outpacing the global average and has already led to boardwalks swamped by swelling tides, drowned forests, submerged wharfs, and threatened historic shoreline buildings.

Recent research suggests that globally, land now occupied by 300 million people could be affected by floods at least once a year by 2050 unless carbon emissions are significantly reduced, and coastal defenses strengthened. (This new figure is more than three times higher than earlier estimates).

Researchers at Dalhousie University in Nova Scotia are studying nature-based strategies for mitigating the effects of the rising seas. These include conserving or restoring coastal ecosystems like dunes, wetlands, and reefs which could provide protection at a lower cost than building seawalls and other man-made obstacles. Wetlands, for example, can reduce the force of waves and act as obstacles to storm surges, while also trapping sediment and stemming erosion. Wetlands also serve as important carbon stores, but it is estimated that roughly half of the world’s coastal wetlands have been lost over the past 100 years to human activity and extreme weather events.

**********

Web Links

The Looming Threat of Rising Sea Levels – And What We Can Do About it

Photo, posted February 14, 2015, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Record Polar Ice Melting | Earth Wise

Web Links

The Rising Threat Of Rising Seas | Earth Wise

Global sea level rose by about 6 inches during the 20th century. It is currently rising more than twice as fast and accelerating. The rate of rise was 2.5 times faster from 2006 to 2016 than it was for nearly all of the 20th century.

Web Links