Climate Science: High levels of molecular Chlorine found in Arctic atmosphere

The researchers directly measured molecular chlorine levels in the Arctic in the spring of 2009 over a six-week period using chemical ionization mass spectrometry.

Scientists studying the atmosphere above Barrow, Alaska, have discovered unprecedented levels of molecular chlorine in the air, a new study reports.

Molecular chlorine, from sea salt released by melting sea ice, reacts with sunlight to produce chlorine atoms.

These chlorine atoms are highly reactive and can oxidize many constituents of the atmosphere including methane and elemental mercury, as well activate bromine chemistry, which is an even stronger oxidant of elemental mercury.

Oxidized mercury is more reactive and can be deposited to the Arctic ecosystem.

The study is the first time that molecular chlorine has been measured in the Arctic, and the first time that scientists have documented such high levels of molecular chlorine in the atmosphere.

"No one expected there to be this level of chlorine in Barrow or in polar regions," said Greg Huey, a professor in the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology in Atlanta.

The study was published January 12 in the journal Nature Geoscience and was supported by the National Science Foundation (NSF), part of the international multidisciplinary OASIS program.

The researchers directly measured molecular chlorine levels in the Arctic in the spring of 2009 over a six-week period using chemical ionization mass spectrometry.

At first the scientists were skeptical of their data, so they spent several years running other experiments to ensure their findings were accurate.

The level of molecular chlorine above Barrow was measured as high as 400 parts per trillion, which is a high concentration considering that chlorine atoms are short -lived in the atmosphere because they are strong oxidants and are highly reactive with other atmospheric chemicals.

Molecular chlorine concentrations peaked in the early morning and late afternoon, and fell to near-zero levels at night.

Average daytime molecular chlorine levels were correlated with ozone concentrations, suggesting that sunlight and ozone may be required for molecular chlorine formation.

Previous Arctic studies have documented high levels of oxidized mercury in Barrow and other polar regions.

The major source of elemental mercury in the Arctic regions is coal-burning plants around the world. In the spring in Barrow, ozone and elemental mercury are often depleted from the atmosphere when halogens - chlorine and bromine - are released into the air from melting sea ice.

"Molecular chlorine is so reactive that it's going to have a very strong influence on atmospheric chemistry," Huey said.

More Information: "High Levels of Molecular Chlorine in Arctic Atmosphere" doi:10.1038/ngeo2046

MODIS Image: Pine Island Glacier 2013

This MODIS image taken by NASA’s Aqua satellite on Nov. 10, 2013, shows an iceberg that was part of the Pine Island Glacier and is now separating from the Antarctica continent.

What appears to be a connection point on the top left portion of the iceberg is actually ice debris floating in the water.

The original rift that formed the iceberg was first observed in October 2011 but as the disconnection was not complete, the “birth” of the iceberg had not yet happened.

It is believed the physical separation took place on or about July 10, 2013, however the iceberg persisted in the region, adjacent to the front of the glacier.

The iceberg is estimated to be 21 miles by 12 miles (35 km by 20 km) in size, roughly the size of Singapore. 

A team of scientists from UK's Sheffield and Southampton universities will track it and try to predict its path using satellite data.

Image credit: NASA

Antarctic Peninsula climate reconstruction: Ice Melt intensified ten-fold

Credit: British Antarctic Survey 

A new 1000-year Antarctic Peninsula climate reconstruction shows that summer ice melting has intensified almost ten-fold, and mostly since the mid 20th Century. Summer ice melt affects the stability of Antarctic ice shelves and glaciers. 

The research, published this week in the journal Nature Geoscience, adds new knowledge to the international effort that is required to understand the causes of environmental change in Antarctica and to make more accurate projections about the direct and indirect contribution of Antarctica's ice shelves and glaciers to global sea level rise.

In 2008 a UK-French science team drilled a 364-metre long ice core from James Ross Island, near the northern tip of the Antarctic Peninsula, to measure past temperatures in the area.

They discovered that this ice core could also give a unique and unexpected insight into ice melt in the region.

Visible layers in the ice core indicated periods when summer snow on the ice cap thawed and then refroze.

By measuring the thickness of these melt layers the scientists were able to examine how the history of melting compared with changes in temperature at the ice core site over the last 1000-years.

Dr Nerilie Abram

Lead author Dr Nerilie Abram of The Australian National University and British Antarctic Survey (BAS) says, "We found that the coolest conditions on the Antarctic Peninsula and the lowest amount of summer melt occurred around 600 years ago. "

"At that time temperatures were around 1.6°C lower than those recorded in the late 20th Century and the amount of annual snowfall that melted and refroze was about 0.5%. "

"Today, we see almost ten times as much (5%) of the annual snowfall melting each year. "

"Summer melting at the ice core site today is now at a level that is higher than at any other time over the last 1000 years, and whilst temperatures at this site increased gradually in phases over many hundreds of years, most of the intensification of melting has happened since the mid-20th century."

This is the first time it has been demonstrated that levels of ice melt on the Antarctic Peninsula have been particularly sensitive to increasing temperature during the 20th Century.

Dr Abram explains, "What that means is that the Antarctic Peninsula has warmed to a level where even small increases in temperature can now lead to a big increase in summer ice melt." 

2012 Greenland Ice Melt Strongest On Record, More to Come

New data shows that melting of the vast ice sheet that covers more than three-quarters of Greenland is the strongest ever seen -- and there are still four weeks to go in the melting season.

Marco Tedesco, a researcher at the City College of New York, says the melting that scientists have observed in 2012 has already outstripped the melt in 2010. The melting season typically lasts from June to early September.

"With more yet to come in August, this year's overall melting will fall way above the old records," Tedesco said in a statement Monday.

"That's a goliath year, the greatest melt since satellite recording began in 1979."

This latest observation has not yet been published in a peer-reviewed journal, but Tedesco and his colleagues have a forthcoming paper looking at models projecting gains and losses to the ice sheet throughout the rest of this century.

NASA announced in July that its Earth Observation satellites (Modis, Aqua, Terra) had found that about 97 percent of the ice sheet's 660,000 square-mile surface had undergone melting.

This latest data from Tedesco and his colleagues jives with that finding. They used data from microwave satellite sensors in order to calculate the cumulative melting index, which gauges the "strength" of the melting season.

The index is generated by multiplying the number of days the ice sheet has melted by the total area of the ice sheet that has melted.

Rutgers University in Greenland

Åsa Rennermalm, a Rutgers University Hydrologist and researcher unaffiliated with the current project, studies the streams and rivers both on the ice sheet and those that are fed by meltwater.

She says the residents of Kangerlussauq, a town near her research site, confirm that this season's melt is the biggest they remember.

Kangerlussauq, which contains Greenland's major airport, was directly impacted by the higher melt on July 11, when a major bridge was destroyed by rising river, fed by melt-water.

"It was pretty dramatic," Rennermalm said.

Byrd Polar Research centre

Tedesco's colleague Jason Box, a researcher at Ohio State University's Byrd Polar Research Center, says there's a positive feedback mechanism at play in the ice sheet's melting; as the surface melts, it gets darker, which absorbs more heat from the sun.

In a downward spiraling action, the melted surfaces absorb more heat and this encourages further melting.

NASA Terra Satellite Image: Arctic Ice Melt in Northwest Passage

This image, taken on Aug. 3, 2012, shows that most of the ice in the Parry Channel, part of the Northwest Passage, has melted away.

CREDIT: NASA Earth Observatory

Sea ice has melted and part of the Arctic's Northwest Passage has opened, images captured by NASA's Terra satellite show.

An image taken on July 17 shows ice filled Parry Channel, part of the Passage, at that point. The second photo, taken two weeks later on Aug. 3, shows that most of the ice has melted away.

The Canadian Ice Service reported that ice cover in Parry Channel began to fall below the 30-year median level in mid-July, and the melting sped up in the following two weeks. At the end of July, there was only an ice cover of 30 percent, compared to a median of 79 percent.

While the Parry Channel appears almost entirely free of ice, it's not necessarily open for ships to pass through, according to a NASA release. Sea ice can be thin enough to avoid detection by satellite sensors yet still thick enough to impede ships.

Whether or not ships can easily pass, recent studies have suggested that certain organisms have begun to take advantage of the open water. When the Northwest Passage opened in 2007, a study found that a type of plankton usually found in the Pacific had turned up in the North Atlantic.

Another study found that Pacific and Atlantic populations of Bowhead whale began to overlap in the Northwest Passage in 2010, according to the release.

The search for a shortcut between Europe and Asia though the Arctic dates back to Columbus's journey to the Americas. For centuries, attempts failed due to unfamiliar geography and unforgiving ice.

The passage was first successfully navigated by Norwegian explorer Roald Amundsen in 1906. He used the southern route through the Northwest Passage; Parry Channel is part of the northern, shorter route.

NASA Earth Observation Satellites reveal sudden Greenland ice melt

Image Credit: Reuters

Greenland's massive ice sheet has melted this month over an unusually large area, Nasa has said.

Scientists said the "unprecedented" melting took place over a larger area than has been detected in three decades of satellite observation.

Melting even occurred at Greenland's coldest and highest place, Summit station.

The thawed ice area jumped from 40% of the ice sheet to 97% in just four days from 8 July.

Although about half of Greenland's ice sheet normally melts over the summer months, the speed and scale of this year's melting surprised scientists, who described the phenomenon as "extraordinary".

Nasa said that nearly the entire ice cover of Greenland, from its thin, low-lying coastal edges to its centre, which is 3km (two miles) thick, experienced some degree of melting at its surface.

"When we see melt in places that we haven't seen before, at least in a long period of time, it makes you sit up and ask what's happening," Nasa chief scientist Waleed Abdalati said.

"It's a big signal, the meaning of which we're going to sort out for years to come."

He said that, because this Greenland-wide melting has happened before, Nasa is not yet able to determine whether this is a natural but rare event, or if it has been sparked by man-made global warming.

Scientists said they believed that much of Greenland's ice was already freezing again.

Until now, the most extensive melting seen by satellites in the past three decades was about 55% of the area.

Ice last melted at Summit station in 1889, ice core records show.

The news comes just days after Nasa satellite imagery revealed that a massive iceberg, twice the size of Manhattan, had broken off a glacier in Greenland.

"This event, combined with other natural but uncommon phenomena, such as the large calving event last week on Petermann Glacier, are part of a complex story," said Nasa's Tom Wagner.

NASA Leads Study of Unprecedented Arctic Ozone Loss

Left: Ozone in Earth's stratosphere at an altitude of approximately 12 miles (20 kilometers) in mid-March 2011, near the peak of the 2011 Arctic ozone loss. 

Right: chlorine monoxide – the primary agent of chemical ozone destruction in the cold polar lower stratosphere – for the same day and altitude.

Image credit: NASA/JPL-Caltech

A NASA-led study has documented an unprecedented depletion of Earth's protective ozone layer above the Arctic last winter and spring caused by an unusually prolonged period of extremely low temperatures in the stratosphere.

The study, published online Sunday, Oct. 2, in the journal Nature, finds the amount of ozone destroyed in the Arctic in 2011 was comparable to that seen in some years in the Antarctic, where an ozone "hole" has formed each spring since the mid-1980s.

The stratospheric ozone layer, extending from about 10 to 20 miles (15 to 35 kilometers) above the surface, protects life on Earth from the sun's harmful ultraviolet rays.

The Antarctic ozone hole forms when extremely cold conditions, common in the winter Antarctic stratosphere, trigger reactions that convert atmospheric chlorine from human-produced chemicals into forms that destroy ozone.

The same ozone-loss processes occur each winter in the Arctic. However, the generally warmer stratospheric conditions there limit the area affected and the time frame during which the chemical reactions occur, resulting in far less ozone loss in most years in the Arctic than in the Antarctic.



To investigate the 2011 Arctic ozone loss, scientists from 19 institutions in nine countries (United States, Germany, The Netherlands, Canada, Russia, Finland, Denmark, Japan and Spain) analyzed a comprehensive set of measurements.

These included daily global observations of trace gases and clouds from NASA's Aura and CALIPSO spacecraft; ozone measured by instrumented balloons; meteorological data and atmospheric models.

The scientists found that at some altitudes, the cold period in the Arctic lasted more than 30 days longer in 2011 than in any previously studied Arctic winter, leading to the unprecedented ozone loss. Further studies are needed to determine what factors caused the cold period to last so long.

"Day-to-day temperatures in the 2010-11 Arctic winter did not reach lower values than in previous cold Arctic winters," said lead author Gloria Manney of NASA's Jet Propulsion Laboratory in Pasadena, Calif., and the New Mexico Institute of Mining and Technology in Socorro.

"The difference from previous winters is that temperatures were low enough to produce ozone-destroying forms of chlorine for a much longer time. This implies that if winter Arctic stratospheric temperatures drop just slightly in the future, for example as a result of climate change, then severe Arctic ozone loss may occur more frequently."

Antarctica rising as ice caps melt

ANTARCTICA is rising like a cheese soufflé: slowly but surely. 

Lost ice due to climate change and left-over momentum from the end of the last big ice age mean the buoyant continent is heaven-bound.

Donald Argus of NASA's Jet Propulsion Laboratory in Pasadena, California, and colleagues used 15 years of GPS data to show that parts of the Ellsworth mountains in west Antarctica are rising by around 5 millimetres a year (Geophysical Research Letters, DOI: 10.1029/2011gl048025). 

Elsewhere on the continent, the rise is slower.

A faster rise has been seen in Greenland, which is thought to be popping up by 4 centimetres a year.

Ongoing climate change could be partly to blame: Antarctica is losing about 200 gigatonnes of ice per year, and for Greenland the figure is 300 gigatonnes. Earth's continents sit on viscous magma, so the effect of this loss is like taking a load off a dense foam mattress.

But there is another possible contributor. "The Earth has a very long memory," says Argus. As a result, "there is also a viscous response to ice loss from around 5000 to 10,000 years ago going on".

Despite this effect, the known ice loss at both poles suggests that embedded in the local rises is a signal of current climate change - researchers just have to tease it out.

NASA Terra's MODIS: Sunny Skies over Arctic Sea Ice

Clear skies allowed the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite a largely unobstructed view of the Arctic in early July 2011.

This scene is a mosaic of observations acquired by MODIS on July 11, 2011. This natural-colour mosaic shows Arctic sea ice and the brilliant white ice cap on Greenland.

High-pressure weather systems tend to bring sunny skies and high temperatures. The National Snow and Ice Data Center (NSIDC) reported that a high-pressure system occurred over the central Arctic and the Beaufort Sea in June, and high-pressure conditions persisted over the Beaufort Sea in the first half of July.

Over the North Pole, and the Laptev and East Siberian Seas, temperatures were higher than normal in the first half of July, although they were lower than normal over the Kara Sea.

The same tilt in Earth’s axis that brings about seasonal changes also brings the Arctic maximum sunlight around late June and early July. When clear skies persist over the region at the same time, this can reinforce summertime sea ice melt.

In parts of the Arctic, spring sea ice melt began earlier than usual, NSIDC stated.

On July 18, 2011, NSIDC reported that Arctic sea ice had declined at a rapid pace during the first half of July, and is currently tracking below the trend line for 2007. In September 2007, Arctic sea ice set a record low. Whether 2011 will set a new record, however, is yet to be seen.

The large version of this image has a resolution of 1 kilometer.

ESA ERS-2: Satellite’s final images focus on changing glaciers

Time-lapse animation of images of the Kangerdlugssuaq ice stream taken from March to May 2011. The animation shows the ice stream advancing steadily at a speed of about 35 m per day, until a 9 sq km piece of the glacier broke into icebergs during 19–22 May.

Credits: ESA

Some of the last images from ESA’s ERS-2 satellite have revealed rapidly changing glacial features in Greenland. In its final days, the veteran satellite gave us frequent views of the Kangerdlugssuaq glacier and its advancing ice stream.

Before it retired on 6 July, ESA’s ERS-2 Earth observation satellite entered an orbit to capture radar images of the same area on the ground every three days, rather than its previous 35-day cycle.

Images of the Kangerdlugssuaq glacier in eastern Greenland taken from March to May 2011 show that the ice stream was advancing steadily at about 35 m per day.

Then, between 19 and 22 May, a 9 sq km piece of the glacier broke up into icebergs.

Information from this ERS-2 ‘Ice Phase’ is helpful for studying rapid changes such as landslides, tectonics movements, sea ice and growing crops.

Baffin Island: Seasonal Ice Melt

In the depths of winter, ice hugs the coastline of Canada’s Baffin Island. Summertime sunlight, however, dramatically melts the ice away from the coastline.

Seasonal sea ice retreat was well underway when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired this natural-color (photo-like) image on July 11, 2009.

Clouds often hover over the Arctic during the Northern Hemisphere summer, making cloud-free images such as this one relatively rare.

Although a few wispy clouds appear in the upper right and lower left corners of this image, the delicate swirls of white running along the eastern edge of Baffin Island are sea ice.

Eddies along Baffin Island’s coast have fashioned the ice into interlocking swirls, especially near Cumberland Sound. Farther north, a long band of ice holds fast to the shore east of Barnes Icecap.

Although less inclined to move with the currents, this ice also shows signs of weakening, as its edges splinter, and pieces float away.

The sea ice retreat captured in this image appears typical of seasonal melt. Since the turn of the twenty-first century, however, Arctic sea ice extent has declined sharply, experiencing a series of low summertime extents and poor wintertime recoveries.

Arctic sea ice extent set a record low in September 2007. As of July 22, 2009, the National Snow and Ice Data Center reported that, in the first half of July 2009, sea ice declined faster than it did in 2008, but not as fast as it did in 2007.