Polar ice caps like Greenland and Antarctica are releasing six times more ice than throughout the 1990s, contributing to a higher sea level that could produce annual flooding by 2100 in areas in which now 400 million people live, experts have warned.
The ice sheets with kilometers in thickness on top of the landmasses at the planet’s poles shed 6.4 trillion tons of mass from 1992 all the way to 2017, adding about two centimeters to the global watermark, as per a study led by a group of 89 researchers, the most detailed so far.
The heat the Arctic endured last summer will probably top the 2011 record for polar ice layer loss of 552 billion tons, the researchers reported in two separate studies published in the Nature journal on Wednesday, March 11th.
Although the rising sea levels are not as visible as other nature-led and climate-driven forces like hurricanes, they eventually prove the most harmful of global warming impacts. It is the added amounts that make storms from climate-aided tropical cyclones more devastating, according to the specialists.
“Every centimeter of sea-level rise leads to coastal flooding and coastal erosion, disrupting lives around the planet,” said University of Leeds professor Andrew Shepherd, who led the research together with Erik Ivins from NASA’s Jet Propulsion Laboratory. “If Antarctica and Greenland continue to track worst-case climate warming scenarios, they will cause an extra 17 centimeters of sea-level rise by the end of the century.”
This is approximately a third of the rise prediction for 2100 by the U.N.’s climate science advisory panel according to a scenario midway between a quick drawdown of worldwide greenhouse gases, and the insane expansion of fossil fuel use, seen as unlikely.
Thawing glaciers and the increase of ocean water as it warms contributed to the majority of the rise in sea level during the 20th century, but the ice sheets melting has become a main culprit over the last ten years.
Sea Level Increase
Almost all the ice shedding from Antarctica, as well as half of that from Greenland, have been caused by warming ocean water accelerating the movement of glaciers toward the sea. Oceans absorb more than 90 percent of the surplus heat from global warming. The rest of Greenland’s ice losses is triggered by the rising air temperatures, which produces flows of ocean-bound meltwater in summer.
The merged rate of mass loss from both ice caps increased by six times from 81 billion to 476 billion tons per year throughout less than three decades, the studies said. The assessments are based on decades of satellite data, site measurements, and computer modeling.
“Satellite measurements provide prima facie, irrefutable evidence,” said Ivins.
The IPCC predicts about half a meter of sea rise by 2100 under the midway emissions scenario, known as RCP4.5. If humanity beats the odds and attains carbon neutrality by the middle of the century, the rise in sea level will probably be covered at 43 centimeters.
Earth‘s overall surface temperature has warmed one degree Celsius (1.8 degrees Fahrenheit) during pre-industrial levels, but polar areas have heated up twice as much. Greenland and West Antarctica both have sufficient water to raise the oceans by about 13 meters.
The remaining regions of Antarctica, which is a bit more stable, supports over 50 meters of possible sea-level increase.