Meltdown in the Arctic is speeding up

Ice at the North Pole melted at an unprecedented rate last week, with leading scientists warning that the Arctic could be ice-free in summer by 2013.

Satellite images show that ice caps started to disintegrate dramatically several days ago as storms over Alaska's Beaufort Sea began sucking streams of warm air into the Arctic.

As a result, scientists say that the disappearance of sea ice at the North Pole could exceed last year's record loss. More than a million square kilometres melted over the summer of 2007 as global warming tightened its grip on the Arctic. But such destruction could now be matched, or even topped, this year.

'It is a neck-and-neck race between 2007 and this year over the issue of ice loss,' said Mark Serreze, of the US National Snow and Ice Data Centre in Boulder, Colorado. 'We thought Arctic ice cover might recover after last year's unprecedented melting - and indeed the picture didn't look too bad last month. Cover was significantly below normal, but at least it was up on last year.

'But the Beaufort Sea storms triggered steep ice losses and it now looks as if it will be a very close call indeed whether 2007 or 2008 is the worst year on record for ice cover over the Arctic. We will only find out when the cover reaches its minimum in mid-September.'

This startling loss of Arctic sea ice has major meteorological, environmental and ecological implications. The region acts like a giant refrigerator that has a strong effect on the northern hemisphere's meteorology. Without its cooling influence, weather patterns will be badly disrupted, including storms set to sweep over Britain.

At the same time, creatures such as polar bears and seals - which use sea ice for hunting and resting - face major threats. Similarly, coastlines will no longer be insulated by ice from wave damage and will suffer erosion, as is already happening in Alaska.

Other environmental changes are likely to follow. Without sea ice to bolster them, land ice - including glaciers - could topple into the ocean and raise global sea levels, threatening many low-lying areas, including Bangladesh and scores of Pacific islands. In addition, the disappearance of reflective ice over the Arctic means that solar radiation would no longer be bounced back into space, thus heating the planet even further.

On top of these issues, there are fears that water released by the melting caps will disrupt the Gulf Stream, while an ice-free Arctic in summer offers new opportunities for oil and gas drilling there - and for political disputes over territorial rights.

What really unsettles scientists, however, is their inability to forecast precisely what is happening in the Arctic, the part of the world most vulnerable to the effects of global warming. 'When we did the first climate change computer models, we thought the Arctic's summer ice cover would last until around 2070,' said Professor Peter Wadhams of Cambridge University. 'It is now clear we did not understand how thin the ice cap had already become - for Arctic ice cover has since been disappearing at ever increasing rates. Every few years we have to revise our estimates downwards. Now the most detailed computer models suggest the Arctic's summer ice is going to last for only a few more years - and given what we have seen happen last week, I think they are probably correct.'

The most important of these computer studies of ice cover was carried out a few months ago by Professor Wieslaw Maslowski of the Naval Postgraduate School in Monterey, California. Using US navy supercomputers, his team produced a forecast which indicated that by 2013 there will be no ice in the Arctic - other than a few outcrops on islands near Greenland and Canada - between mid-July and mid-September.

'It does not really matter whether 2007 or 2008 is the worst year on record for Arctic ice,' Maslowski said. 'The crucial point is that ice is clearly not building up enough over winter to restore cover and that when you combine current estimates of ice thickness with the extent of the ice cap, you get a very clear indication that the Arctic is going to be ice-free in summer in five years. And when that happens, there will be consequences.'

This point was backed by Serreze. 'The trouble is that sea ice is now disappearing from the Arctic faster than our ability to develop new computer models and to understand what is happening there. We always knew it would be the first region on Earth to feel the impact of climate change, but not at anything like this speed. What is happening now indicates that global warming is occurring far earlier than any of us expected.'

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Soil Studies Continue at Site of Phoenix Mars Lander

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This false-color image shows a soil sample after being delivered to a gap between partially opened doors on the lander's Thermal and Evolved-Gas Analyzer. Image credit: NASA/JPL-Caltech/University of Arizona/Texas A&M University

TUCSON, Ariz. -- NASA's Phoenix Mars Lander has continued studies of its landing site by widening a trench, making overnight measurements of conductivity in the Martian soil and depositing a sample of surface soil into a gap between partially opened doors to an analytical oven on the lander.

Phoenix's robotic arm delivered soil Thursday from a trench informally named "Rosy Red" through a narrow opening to a screen above the No. 5 oven on the lander's Thermal and Evolved-Gas Analyzer (TEGA). A few particles of the sample passed through the screen on Thursday, but not enough to fill the oven and allow analysis of the sample to begin. The Phoenix team sent commands for TEGA to vibrate the screen again on Friday, and more material reached the oven, though still not enough to proceed with analysis.

"There appear to be clumps blocking the opening," said Doug Ming of NASA Johnson Space Center, Houston, the Phoenix team's science lead on Friday. "However, we have seen in the past that when this soil sits for a while, it disperses. We intend to fill an oven with this material, either by additional vibration of the same screen or by opening doors to one of the other TEGA cells."

The conductivity measurements completed Wednesday ran from the afternoon of Phoenix's 70th Martian day, or sol, to the morning of Sol 71. A fork-like probe inserted into the soil checks how well heat and electricity move through the soil from one prong to another.

Friday's activities by the spacecraft included extending the width of an exploratory trench informally named "Neverland," which extends between two rocks on the surface of the ground.

The Phoenix mission is led by Peter Smith of The University of Arizona with project management at the Jet Propulsion Laboratory and development partnership at Lockheed Martin, located in Denver. International contributions come from the Canadian Space Agency; the University of Neuchatel; the universities of Copenhagen and Aarhus, Denmark; Max Planck Institute, Germany; and the Finnish Meteorological Institute.

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Is Mars Between Ice Ages?

"Mars is not a dead planet -it undergoes climate changes that are even more pronounced than on Earth."

James Head, planetary geologist, Brown University

The prevailing thinking is that Mars is a planet whose active climate has been confined to the distant past. About 3.5 billion years ago, the Red Planet had extensive flowing water and then fell quiet - deadly quiet. It didn't seem the climate had changed much since. Now, recent studies by scientists at Brown University show that Mars' climate has been much more dynamic than previously believed.

After examining stunning high-resolution images taken last year by the Reconnaissance Orbiter, researchers have documented for the first time that ice packs at least 1 kilometer (0.6 miles) thick and perhaps 2.5 kilometers (1.6 miles) thick existed along Mars' mid-latitude belt as recently as 100 million years ago. In addition, the team believes other images tell them that glaciers flowed in localized areas in the last 10 to 100 million years - a blink of the eye in Mars's geological timeline.

This evidence of recent activity means the Martian climate may change again and could bolster speculation about whether the Red Planet can, or did, support life.

"We've gone from seeing as a dead planet for three-plus billion years to one that has been alive in recent times," said Jay Dickson, a research analyst in the Department of Geological Sciences at Brown and lead author. "[The finding] has changed our perspective from a planet that has been dry and dead to one that is icy and active."

In fact, Dickson and his co-authors, James Head, and David Marchant, a associate professor at Boston University, believe the images show that has gone through multiple Ice Ages - episodes in its recent past in which the planet's mid-latitudes were covered by glaciers that disappeared with changes in the Red Planet's obliquity, which changes the climate by altering the amount of sunlight falling on different areas.

NASA's Global Surveyor and Odyssey missions have provided evidence of a relatively recent ice age on Mars. In contrast to Earth's ice ages, a Martian ice age expands when the poles warm, and water vapor is transported toward lower latitudes. Martian ice ages wane when the poles cool and lock water into polar icecaps.

The catalysts of ice ages on appear to be much more extreme than the comparable drivers of climate change on Earth. Variations in the planet's orbit and tilt produce remarkable changes in the distribution of water ice from Polar Regions down to latitudes equivalent to Houston or Egypt. Researchers, using NASA spacecraft data and analogies to Earth's Antarctic Dry Valleys, reported their findings in the journal Nature.

"Of all the solar system planets, has the climate most like that of Earth. Both are sensitive to small changes in orbital parameters," said Head. "Now we're seeing that Mars, like Earth, is in a period between ice ages," he said. This evidence of recent activity means the Martian climate may change again and could bolster speculation about whether the Red Planet can, or did, support life.

Head and his team examined global patterns of landscape shapes and near-surface water ice Nasa's orbiters mapped. They concluded a covering of water ice mixed with dust mantled the surface of to latitudes as low as 30 degrees, and is degrading and retreating. By observing the small number of impact craters in those features and by backtracking the known patterns of changes in Mars' orbit and tilt, they estimated the most recent ice age occurred just 400 thousand to 2.1 million years ago.

Marchant, a glacial geologist who spent 17 field seasons in the Mars-like Antarctic Dry Valleys, said, "These extreme changes on Mars provide perspective for interpreting what we see on Earth. Landforms on that appear to be related to climate changes help us calibrate and understand similar landforms on Earth. Furthermore, the range of microenvironments in the Antarctic Dry Valleys helps us read the Mars record."

According to the researchers, during a Martian ice age, polar warming drives water vapor from polar ice into the atmosphere. The water comes back to ground at lower latitudes as deposits of frost or snow mixed generously with dust. This ice-rich mantle, a few meters thick, smooths the contours of the land. It locally develops a bumpy texture at human scales, resembling the surface of a basketball, and also seen in some Antarctic icy terrains. When ice at the top of the mantling layer sublimes back into the atmosphere, it leaves behind dust, which forms an insulating layer over remaining ice. On Earth, by contrast, ice ages are periods of polar cooling. The buildup of ice sheets draws water from liquid-water oceans, which lacks.

Dickson and the other researchers focused on an area called Protonilus Mensae-Coloe Fossae. The region is located in Mars's mid-latitude and is marked by splotches of mesas, massifs and steep-walled valleys that separate the lowlands in the north from the highlands in the south.

The team looked in particular at a box canyon set in a low-lying plain. Images show the canyon has moraines - deposits of rocks that mark the limits of a glacier's advance or the path of its retreat. The rock deposit lines appear to show a glacier that flowed up the box canyon, which "physically cannot happen," Dickson said.

Instead, the team deduced the ice in the surrounding plain grew higher than the canyon's walls and then flowed downward onto the top of the canyon, which had become the lowest point on the ice-laden terrain. The team calculated the ice pack must have been one kilometer thick by past measurements of height between the plain and the lip of the canyon. Based on the ice flow patterns, the ice pack could have reached 2.5 kilometers at peak thickness during a period known as the late Amazonian, the authors said.

The finding could have implications for the life-on-argument by strengthening the case for liquid water. Ice can melt two ways: by temperature or by pressure. As currently understood, the Martian climate is dominated by sublimation, the process by which solid substances are transformed directly to vapor. But ice packs can exert such strong pressure at the base to produce liquid water, which makes the thickness of past glaciers on its surface so intriguing.

Dickson also looked at a lobe across the valley from the box canyon site. There, he saw a clear, semi-circular moraine that had spilled from an ancient tributary on to the surrounding plain. The lobe is superimposed on a past ice deposit and appears to be evidence of more recent glaciation. Although geologists can't date either event, the landscape appears to show at least two periods in which glaciation occurred, bolstering their theory that the Martian climate has undergone past Ice Ages.

Posted by Casey Kazan.

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