Earth Ice Free?

[lathe_biosas]

Merely for the shock factor, I give you the cheapest way to turn down Earth's thermostat: sulfuric aerosol clouds (i.e. imitating a volcanic eruption).

 

Robock et al. 2009. Benefits, risks and costs of geoengineering. Geophysical Research Letters.

http://onlinelibrary.wiley.com/doi/10.1029/2009GL039209/pdf

 

Note that the risks include: ozone depletion, reduced solar power, ruining terrestrial astronomy, military or rogue abuse, commercial profiteering and an overall blow to humanity's drive to prevent the problem in the first place (moral hazard). Something of a Pyrrhic victory.

 

Other geoengineering options include giant solar mirrors and seeding the ocean with micronutrients to encourage biological carbon sequestration. I agree with the researchers that (surprise!) more research is required. Wouldn`t hurt to know how to do this in a pinch.

 

In the meantime, reducing greenhouse gas emissions and shifting to more sustainable technologies would be much safer.

[hh5]

Antarctica is Melting from the Bottom Up

As much as 90 percent of the ice loss in some parts of Antarctica happens beneath the water, according to researchers who report that much more ice is melting from the undersides of submerged ice shelves than previously thought.

Every year 2,800 cubic kilometers leave the Antarctic ice sheet, but for decades the general consensus among scientists was that calving -- where huge chunks of ice break off from glaciers and float out to sea -- was the main source of Antarctic ice loss.

 

Using satellite and climate modeling data, a team of scientists from three universities contend that the sub-shelf melting impacts ice levels in Antarctica have a large impact on overall ice loss just as much as iceberg calving, if not more.

How much ice specific shelves lose to melting versus calving varies dramatically, the researchers report, saying that as much as 90 percent of ice loss can be attributed to sub-shelf melting in some areas, while sub-shelf melting elsewhere on the continent only accounts for 10 percent of ice loss.

"Understanding how the largest ice mass on the planet loses ice to the oceans is one of the most fundamental things we need to know for Antarctica. Until recently, we assumed that most of the ice was lost through icebergs," said Jonathan Bamber from the University of Bristol's School of Geographical Sciences. Bamber conducted the study with researchers from University of California and Utrecht University

"Now we realize that melting underneath the ice shelves by the ocean is equally important and for some places, far more important," Bamber said. "This knowledge is crucial for understanding how the ice sheets interact now, and in the future, to changes in climate."

The research measured the flow of ice, its elevation and its thickness and combined that data with the output of a climate model for snowfall over the ice sheet. By comparing how much snow was falling on the surface and accumulating versus how much ice was leaving the continent, entering the ocean and calving, the scientists were able to determine the percentage of ice that was lost as a function of ice melt and calving.

The paper "Calving fluxes and basal melt rates of Antarctic ice shelves," is published in the journal Nature.

 

 

[mickey1952]

At my age, I can't get too concerned.  Any other comment from me is likely to be considered political. 

I'm with you MikeL. I'm also at the age that by the time that happens my ashes will have been scattered and recycled numerous times.

[hh5]

'Tiger stripes' under Antarctic glaciers slow their flow to the ocean

PRINCETON, N.J., Nov. 8 (UPI) -- Narrow stripes of dirt and rock beneath massive Antarctic glaciers act like no-slip strips on a floor to slow the flow of ice toward the sea, scientists say.

Researchers at Princeton University and the British Antarctic Survey said understanding how the high-friction regions form could help increase understanding of how the glaciers' flow responds to a warming climate.

 

The massive, moving ice sheets can contribute substantially to sea-level rise when they flow into the ocean.

 

Dubbed "tiger stripes" after Princeton's tiger mascot, the formations provide friction that hinders the glaciers from slipping along the underlying bed of rock and sediment, the scientists said.

 

Studying the bottom of mile-and-a-half-thick Antarctic glaciers is next to impossible due to the inability to see through the ice, so the researchers used satellite measurements of the ice velocity and ground-penetrating radar collected from airplane flyovers to detect bedrock and surface topography.

 

The tiger stripes, which the researchers also call ribs, due to their slightly curved structure, lie at roughly 30-degree angles to the direction of the glacier's movement, and arise and decay in response to natural processes over roughly 50 to 100 years, the scientists calculated.

 

The process is strongly affected by how water, melted from the ice by inherent heat trapped inside Earth, infiltrates the space between the ice sheet and the bedrock, they said.

 

"The ribs may play an important role in buffering the effects of a warming climate, since they slow the movement of ice that reaches the ocean and contributes to sea-level rise," Princeton researcher Olga Sergienko said. "These changes can happen independently of climate change, too."

 

 

 

[hh5]

Don't we already know that there is a volcano in the south pole that sometimes plays in the part of melting?

Active volcano discovered under Antarctic ice sheet

Earthquakes deep below West Antarctica reveal an active volcano hidden beneath the massive ice sheet, researchers said in a study published in the journal Nature Geoscience.

 

The discovery finally confirms long-held suspicions of volcanic activity concealed by the vast West Antarctic Ice Sheet. Several volcanoes poke up along the Antarctic coast and its offshore islands, such as Mount Erebus, but this is the first time anyone has caught magma in action far from the coast.

 

"This is really the golden age of discovery of the Antarctic continent," said Richard Aster, a co-author of the study and a seismologist at Colorado State University. "I think there's no question that there are more volcanic surprises beneath the ice."

 

The volcano was a lucky find. The research project, called POLENET, was intended to reveal the structure of Earth's mantle, the layer beneath the crust. In 2010, a team led by scientists from Washington University in St. Louis spent weeks slogging across the snow, pulling sleds laden with earthquake-monitoring equipment.

 

A geologic puzzle

Signs of active and extinct volcanoes pop up all over Antarctica. Ash layers and lava indicate volcanoes spouted while the continent froze during the past 20 million years or more. (An 8,000-year-old ash layer sits above the newly found volcano, but it comes from Mount Waesche, a nearby peak.)

 

"The [West] coast of Antarctica is like a ring of fire," Corr said.

 

The earthquake swarms line up with older volcanoes in the Executive Committee Range, suggesting the volcanic activity there is slowly migrating south by 6 miles (9.6 km) every million years. This migration is perpendicular to the motion of Antarctica's tectonic plate, so a hotspot or mantle plume is not feeding the volcanoes, Lough said. (A mantle plume should make volcanoes that line up parallel to plate motion, like those of the Hawaiian Islands.)

 

The big mystery is figuring out why the volcano and its forerunners even exist. "Antarctica is certainly one of the most fascinating and enigmatic of all of Earth's continents," Aster said. [Video - Antarctica: Solving Geologic Mysteries]

 

Let's set the scene. Antarctica is split by an incredible mountain range. Imagine if Utah's spectacularly steep Wasatch Mountains cleaved North America from Texas all the way to Canada. That's what the Transantarctic Mountains are like. In the West, the land dives off into a deep rift valley, where the crust has been tearing apart for about 100 million years. The newly found volcano sits on the other side of this rift, in a higher-elevation region called Marie Byrd Land.

 

While the torn crust may seem like the best explanation for Antarctica's many volcanoes, many of the peaks fit no obvious pattern. Rifting and volcanism in Antarctica could be like nowhere else on Earth. "What is going on with the crust in Antarctica is still puzzling," Lough said.

 

 

Edited November 18, 2013 by hh5