‘Extreme' Changes Underway in Some of Antarctica’s Biggest Glaciers

A new analysis of satellite data has found "extreme" changes underway at eight of Antarctica's major glaciers, as unusually warm ocean water slips in under their ice shelves.

Antarctica's glaciers carry ice from the interior of the
continent to the ocean. This NASA illustration shows
where the ice is moving fastest; areas in red have the
fastest flow, followed by those in pink and purple. 

The warmer water is eating away at the glaciers' icy grasp on the seafloor. As a result, the grounding line—where the ice last touches bedrock—has been receding by as much as 600 feet per year, a new study shows. Behind the grounding line, the land-based ice then speeds up, increasing the rate of sea level rise.

The new continent-wide measurements of grounding lines suggests a widespread pattern of melting all around Antarctica, said University of Leeds climate researcher Hannes Konrad, lead author of the analysis published today in the scientific journal Nature Geoscience.

Read the Inside Climate News story Bob Berwyn - “‘Extreme' Changes Underway in Some of Antarctica’s Biggest Glaciers.”

Major correction to satellite data shows 140% faster warming since 1998.

A new paper published in the Journal of Climate reveals that the lower part of the Earth’s atmosphere has warmed much faster since 1979 than scientists relying on satellite data had previously thought.

Researchers from Remote Sensing Systems (RSS), based in California, have released a substantially revised version of their lower tropospheric temperature record.

After correcting for problems caused by the decaying orbit of satellites, as well as other factors, they have produced a new record showing 36% faster warming since 1979 and nearly 140% faster (i.e. 2.4 times larger) warming since 1998. This is in comparison to the previous version 3 of the lower tropospheric temperature (TLT) data published in 2009.

Climate sceptics have long claimed that satellite data shows global warming to be less pronounced than observational data collected on the Earth’s surface. This new correction to the RSS data substantially undermines that argument. The new data actually shows more warming than has been observed on the surface, though still slightly less than projected in most climate models.

Read the Carbon Brief story - “Major correction to satellite data shows 140% faster warming since 1998.”

2016 Climate Trends Continue to Break Records

The first six months of 2016 were the warmest
 six-month period in NASA's modern temperature
 record, which dates to 1880.

Two key climate change indicators -- global surface temperatures and Arctic sea ice extent -- have broken numerous records through the first half of 2016, according to NASA analyses of ground-based observations and satellite data.

Each of the first six months of 2016 set a record as the warmest respective month globally in the modern temperature record, which dates to 1880, according to scientists at NASA's Goddard Institute for Space Studies (GISS) in New York. The six-month period from January to June was also the planet's warmest half-year on record, with an average temperature 1.3 degrees Celsius (2.4 degrees Fahrenheit) warmer than the late nineteenth century.

Five of the first six months of 2016 also set records for the smallest respective monthly Arctic sea ice extent since consistent satellite records began in 1979, according to analyses developed by scientists at NASA's Goddard Space Flight Center, in Greenbelt, Maryland. The one exception, March, recorded the second smallest extent for that month.

While these two key climate indicators have broken records in 2016, NASA scientists said it is more significant that global temperature and Arctic sea ice are continuing their decades-long trends of change. Both trends are ultimately driven by rising concentrations of heat-trapping carbon dioxide and other greenhouse gases in the atmosphere.

Read the NASA story - “2016 Climate Trends Continue to Break Records.”

Unseasonable warm spring melts Iceland ice sheet

Last month in Greenland, more than a tenth of the ice sheet’s surface was

Nicola Jones.

melting in the unseasonably warm spring sun, smashing 2010’s record for a thaw so early in the year. In the Antarctic, warm water licking at the base of the continent’s western ice sheet is, in effect, dissolving the cork that holds back the flow of glaciers into the sea; ice is now seeping like wine from a toppled bottle.

The planet’s polar ice is melting fast, and recent satellite data, models, and fieldwork have left scientists sobered by the speed of the sea level rise we should expect over the coming decades. Although researchers have long projected that the planet’s biggest ice sheets and glaciers will wilt in the face of rising temperatures, estimates of the rate of that change keep going up. When the Intergovernmental Panel on Climate Change (IPCC) put out its last report in 2013, the consensus was for under a meter (3.3 feet) of sea level rise by 2100. In just the last few years, at least one modeling study suggests we might need to double that.

Read the environment360 story by Nicola Jones - “Abrupt Sea Level Rise Looms As Increasingly Realistic Threat.”

Antarctic snow accumulation outweighing ice losses - NASA

A

new NASA study says that an increase in Antarctic snow accumulation that began 10,000 years ago is currently adding enough ice to the continent to outweigh the increased losses from its thinning glaciers.

The research challenges the conclusions of other studies, including the Intergovernmental Panel on Climate Change's (IPCC) 2013 report, which says that Antarctica is overall losing land ice.

According to the new analysis of satellite data, the Antarctic ice sheet showed a net gain of 112 billion tons of ice a year from 1992 to 2001. That net gain slowed to 82 billion tons of ice per year between 2003 and 2008.

Read the story at phys.org -“Mass gains of Antarctic Ice Sheet greater than losses, NASA study reports.”

'Jammed' ice sheets threaten extra sea level rise

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elting of floating ice shelves around the continent is accelerating, potentially unlocking extra sea level rise from larger ice sheets jammed behind them The Guardian reports.

Its story, “Antarctic ice shelves are melting dramatically, study finds”, says, “The ice around the edge of Antarctica is melting faster than previously thought, potentially unlocking metres of sea-level rise in the long-term, researchers have warned.

“A team of US scientists looked at 18 years’ worth of satellite data and found the floating ice shelves that skirt the continent are losing 310km3 of ice every year. One shelf lost 18% of its thickness during the period,” is continues.