Global warming: Antarctic ice shelves have thinned 18 percent in the past two decades

Troubling signs of a major meltdown continue

It's not clear when the waters around Antarctica will no longer be able to support production of phytoplankton.

 Global warming is nibbling away at Antarctica’s ice sheets, which show declines of up to 18 percent in a new analysis of satellite data. bberwyn photo.

Staff Report

*More Summit Voice stories on global warming changes in Antarctica.

FRISCO — In the dry language of science, researchers this week said that some of Antarctica’s floating ice shelves have thinned by as much as 18 percent in just a couple of decades — a finding that provides “new insights on how the Antarctic ice sheet is responding to climate change.”

After analyzing 20 years of satellite data, the new NASA-supported study shows the ice volume decline is accelerating under a thickening blanket of greenhouse gases. Merging data from three overlapping missions, the study was able to show the trend over time rather than just offering a snapshot view of the ice.

“Eighteen percent over the course of 18 years is really a substantial change,” said Paolo. “Overall, we show not only the total ice shelf volume is decreasing, but we see an acceleration in the last decade.” said Scripps graduate student Fernando Paolo. Continue reading

Rising sea level to take big bite from Hawaii beaches

Study projects increasing rate of coastal erosion

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The Hawaiian Islands via NASA Earth Observatory.

Staff Report

FRISCO — As sea level rises, Hawaii’s beaches are on track to shrink by 20 to 40 feet during the next few decades, scientists announced in a new study.

“When we modeled future shoreline change with the increased rates of sea level rise projected under the IPCC’s “business as usual” scenario, we found that increased SLR causes an average 16 – 20 feet of additional shoreline retreat by 2050,” said lead author Tiffany Anderson, a post-doctoral researcher at the UHM School of Ocean and Earth Science and Technology. Continue reading

Climate: More melting ahead for East Antarctica glaciers

Seafloor channels sluicing warm ocean water toward base of East Antarctica’s Totten Glacier

Increasing concentrations of CO2 could turn this Antarctic beach into a tropical zone. Photo by Bob Berwyn.

Are Antarctica’s ice sheets near a global warming tipping point? bberwyn photo.

Staff Report

FRISCO — Scientists say they’re a step closer to understanding the extreme thinning of East Antarctica’s largest glacier, which contains enough ice to raise global sea level by about 11 feet.

Ocean gateways are sluicing warm water toward the base of the Totten Glacier near the shoreline, undercutting the icy anchors that slow the advance of the ice toward the sea, according to researchers with the University of Texas at Austin’s Institute for Geophysics, who outline their findings in the March 16 edition of the journal Nature Geoscience.

Similar findings from the region were reported by Australian scientists just a few weeks ago, and another study showed widespread thinning of ice in East Antarctica. Continue reading

How do Antarctica snowfall rates affect sea level rise?

New ice core analysis shows less of an ‘offset’ than most models currently project

Antarctica permafrost

Increasing snowfall in Antarctica will moderate the rate of global sea level rise — but not as much as previously thought. bberwyn photo.

Staff Report

FRISCO — Detailed ice core records from Antarctica show that snowfall over the frozen continent increased about 5 percent for each degree (Celsius) of warming as Earth emerged from the last ice age.

The findings confirm that the increased snowfall will slightly offset sea level rise, as suggested by other research — but not as much as previously thought. That means that some computer models may be underestimating the amount and rate of future sea level rise if they’re based on inaccurate assumptions. Continue reading

Climate: Study shows that just a little bit of warming could destabilize West Antarctic ice sheets

Meeting in Uruguay, an Antarctic science committe advocated for the 2012 establishment of marine reserves in the Southern Ocean and the Ross Sea. PHOTO BY BOB BERWYN.

Will the West Antarctic Ice Sheet slip-slide away as the Southern Ocean warms up? bberwyn photo

A delicate balance

Staff Report

FRISCO — West Antarctica ice sheets are delicately anchored in place along a narrow sliver called the grounding zone, and new research shows that even slight increases in regional ocean and air temperatures are likely to destabilize the ice. The grounding zone is a sloping rock bed that lies below sea level.

In the new study, published this month in the Journal of Glaciology, Caltech scientists said future estimates of sea level rise need to take into account that the ice sheets are more sensitive to temperature perturbations driven by climate change than previously thought.

“Our results show that the stability of the whole ice sheet and our ability to predict its future melting is extremely sensitive to what happens in a very small region right at the grounding line. It is crucial to accurately represent the physics here in numerical models,” said study coauthor Andrew Thompson, an assistant professor of environmental science and engineering at Caltech. Continue reading

Study explores Greenland Ice Sheet plumbing

A meltwater lake on the surface of the Greenland Ice Sheet. Now researchers are tracking where that water goes, and how it may affect ice sheet movement. Photo courtesy Thomas Nylen, NSF.

A meltwater lake on the surface of the Greenland Ice Sheet. Now researchers are tracking where that water goes, and how it may affect ice sheet movement. Photo courtesy Thomas Nylen, National Science Foundation.

Surface meltwater feeds subglacial lakes

Staff Report

FRISCO — Scientists who recently took a close look at the “plumbing” of the Greenland Ice Sheet say that meltwater from the surface is building up lakes beneath the ice and transporting heat to the bottom of the ice sheet.

The research, led by Cornell University Earth and Atmospheric Sciences researcher Michael Willis, includes groundbreaking findings that give new information about atmospheric warming and its affect on the critical zone at the base of the ice. The warmth provided by the water could make the ice sheet move faster and alter how it responds to the changing climate. The research is detailed in a new paper published online by the journal Nature on Jan. 21. Continue reading

Study: Florida’s beach-hardening strategy threatens green sea turtle nesting areas

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A green sea turtle. Photo courtesy NOAA.

‘Smart’ adaptation plans needed to protect critical beach nesting habitat

Staff Report

FRISCO — Florida’s strategy of trying to “harden” beaches to prevent erosion poses a serious threat to sea turtles, university scientists said this week, outlining results of a study that tracked reproduction for 30 years.

Hardening beaches puts up barriers to wildlife and impacts sea turtles’ ability to nest,” the researchers said. Continue reading

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