Flikr Photostream

www.flickr.com
Groat's Leadership photoset Groat's Leadership photoset

Wednesday, June 5, 2013

Arctic Climate Change : The Big Melt



2012 Arctic Sea Ice Minimum
Climate change in the Arctic happens faster than anywhere on the planet, a scientific fact that finds little dispute from any interest group.  For many years, it has been described as the canary in the coal mine (Michaels, 2004).  As circumpolar leaders and experts met at the Arctic Imperative Summit in the Summer of 2012, the recession of Arctic ice, a.k.a. the ice melt, had exceeded 2007 levels (NSIDC, 2012), the previous record Arctic sea ice area recorded since 1979.

While the Arctic shows evidence of global climate change at a faster rate than other areas, it would present a very attractive subject for research and study.  There is room to expand the interdisciplinary aspect of the many scientific fields studying climate change impacts in the high Arctic, but this is offset by the difficulty and expense of reaching Arctic areas and then conducting research (Hinzmon, 2005).


The challenges are real, the Arctic is changing quickly, and projections of increased economic activity in the Circumpolar World are inevitable.  Recognition of the consequences of accelerating climate change for Arctic environments will aid the voices advocating for more research funding on the part of all the Circumpolar World.


Swedish researchers note a generalized loss of cold winters and cool summers while noting more extreme precipitation events.  Their understanding of the rate of climate change has led them to focus on adaptation strategy.  Like many entities, the circumpolar governments and regional stakeholders are turning more and more energy to the adaptation process (Callaghan, et al., 2010).  In the eyes of all the circumpolar nations, the debate as to if the climate is changing is long gone.  The conversation is now about how best to adapt since their part of the planet will be impacted fastest.

Reduction of Arctic Ice

The reduction of Arctic Ice creates a variety of issues and opportunities.  The issue from the standpoint of ice melting is that polar ice reflects light (and heat).  As the ice melts, the dark water surface absorbs more heat, this creates faster temperature rise which, in turn, causes the ice melt to occur at a faster rate.  This kind of feedback system, referred to as a positive feedback loop, is one of many components that impact global climate change. Water on top of the ice pack also creates more rapid heat absorption because it creates a dark area on the ice surface, absorbing more heat.  While melting Arctic ice does not cause sea levels to rise, much like a melting ice cube in a glass of water does not cause the level of liquid in the glass to rise; it does create warmer temperatures which cause other circumpolar ice to melt.  As large amounts of land based ice melt, like the Greenland Ice Shelf, that does introduce more water into the ocean, which does raise sea level. 

As Arctic ice minimums continue to advance, creating more dark water, the ramifications impact not only the acceleration of temperature change, but it also creates young ice areas which require less energy to melt.  The National Snow and Ice Data Center tracks daily changes in the Arctic ice cover.  The Arctic ice recedes yearly and melts during the warm months, typically stopping their recession around the end of September when it becomes cold enough for the ice coverage to begin extending again.  In 2012, the Arctic ice minimum was found to be at the lowest levels since this data has been tracked by satellite (NSIDC, 2012).

The Greenland Ice Sheet

The Greenland Ice Sheet is a massive land based circumpolar ice deposit.  This vast area of ice is starting to undergo rapid melting cycles.  While this has been noted by scientists for many years, the rapid acceleration of Greenland’s ice combined with additional complicating factors, are only recently emerging as an environmental issue that is starting to command global interest.

Unusual weather patterns noted in 2012 include the U.S. drought, and a sudden widespread surface melt event impacting the Greenland Ice Sheet.  This set of circumstances, known as a heat dome, occurs when the jet stream patterns keep cooler air to the north which, in turn, allows warmer air from the Gulf stream to rise up to Greenland.  The phenomena this year, in July, caused a rapid spread of surface melt in Greenland, extending the area from about 40% of Greenland’s surface to nearly complete coverage over the course of four days.

Typically, the maximum surface melt area in Greenland during the hottest point of the summer is around 50%.  The scope of these phenomena is certainly attention getting but there is also evidence this may be part of a cyclical event.  While there is not enough evidence to suggest this predicts an impending catastrophic ice loss and resultant accelerated rates of sea level rise, it certainly warrants further investigation and attention.

If instability and accelerating melting takes place on the Greenland Ice Sheet and the Antarctic, the level of sea rise could be far faster than was originally thought.  It seems like scientists continue to be surprised each year as the rate of change exceeds the predictive components of their models.

If there is a tipping point and the largest of the land based glaciers melt into the ocean, we would have sea levels that are several meters higher than they are now.  Under the most prepared scenario, it is hard to imagine to what extent such an incident would damage global trading patterns and to what extent that would impact weather.


Greenland Ice Sheet Melt July 2012

Satellite Data from NASA’s Gravity Recovery and Climate Experiment satellite taken between 2002 and 2008; demonstrate that Greenland has been losing approximately 195 cubic kilometers of ice per year.  A large section of the Pederson glacier, some 130 square kilometers, broke off due to the high temperatures, but since this section was already floating on the ocean, it will not contribute to rising sea levels.  That said, as similar weather patterns repeat in conjunction with rising average air temperatures, the rate of melt on land is likely to grow. 

Pederson Glacier Ice Melt

Ice melt rate is also affected by other factors, including airborne particulates raining out over the ice sheet causing dark spots.  Images of these dark spots evoke an interest in knowing if they are hydrologically isolated from sub surface water.  The dark holes appear to be bore holes.  These holes initially absorb solar energy at a higher rate causing an increases the rate of melt in the holes.

Black Holes on Greenland Ice Shelf
As the holes get deeper, the rate of deepening begins to rescind as the exposure angle to the sun decreases, and at some point the rate of melt equalizes with surrounding ice.  As these holes create a matrix of higher melt points, they become subject to interrelationships with under surface fissures and fractures of the major ice sheets.  To the extent these many drain into large ice sheet fractures, the rate of progression to land based ice and land contact points tends to create an opportunity for ice to shift and move, probably a lot sooner than it otherwise would have.

Particulates that absorb heat like black carbon, vanillic acid, and sulphur that fall on the Greenland ice shelf create the aforementioned dark areas creating bore holes that melt faster than the surrounding reflective white ice.  This functions like drilling holes in the ice sheet which facilitates gravity dependent water flow migration towards the bottom of the sheet, creating subsurface conditions that encourage a more rapid rate of ice migration towards the sea.

Particulate driven cryoconite holes that look like bore holes have also been widely reported by glaciologists, especially those who study the Greenland ice shelf.  It is thought, based on the chemical composition of the soot that much of it comes from coal burning plants in Asia; this is based on assumptions of wind conditions and observable fallout patterns.

Rivers of water are also noted with massive drop offs into large crevasse structures.  It’s the combination of rising surface temperatures, particulate fallout from high emission industrial output that creates what appears to be a causing accelerated migration of surface water to the ice bedrock interface (Zwally, et al., 2002).  It may also be presumed these holes contribute integrity challenges to the ice sheet, probably creating larger areas that break off as the ice sheet approaches the ocean.  Other chemical compositions suggest some of the soot is due to massive forest fires in other parts of the globe, another by-product of climate change as large forested areas undergo significant drought during the summer months, hence creating ideal conditions for large forest fires.

Ice core samples reveal coal soot particulate content in the Arctic can be correlated to the maximum effect of the industrialization of the period from 1906 to 1910 (McConnell, 2007) and note thermal temperature rises eight times larger than pre-industrialization.  Much of that, by the way, is thought to have derived from the United States and Canada.

Ice Core Samples

Ice core samples, through trapped air pockets, can be analyzed to reveal carbon dioxide in the atmosphere during previous eras.  There is ample evidence that CO2 levels in the atmosphere correlate with average mean surface temperatures due to the heat trapping ability of the material in the Earth’s atmosphere.  The projections of CO2 emissions through the remainder of the 21st century are substantial.  Even with efforts to mitigate emissions, the ramifications imply increased temperatures which mean the planet will continue to shed ice.

Ice Core CO2 Analysis & Predictions

Eastern Siberian Arctic Shelf Carbon Deposits and Methane

Eastern Siberian Arctic Shelf Carbon Deposits of Methane and carboniferous materials on Arctic coastal areas also represent a considerable store of materials that have potential to release greenhouse gas emissions that will accelerate the rate of climate change.  The Eastern Siberian Arctic Shelf (ESAS) covers approximately 7,000 kilometers with significant outcroppings of complex ancient ice deposits rich in carboniferous materials in addition to shallow sub-sea permafrost.  This exists throughout the entire Arctic region to some extent, but the ESAS is by far the most proliferous.

Eastern Siberian Arctic Shelf
As climate change creates larger open water areas in the Arctic for longer periods of time, erosion of these shelves increase releasing carboniferous materials into the ocean.  Microbial consumption of these materials produces carbon dioxide and methane.  The release of carbon dioxide and methane vent to the atmosphere.  Massive deposits of methane hydrates are also known to exist in the form of methane hydrates in a frozen state trapped beneath the Arctic tundra.

Coastal erosion due to increased tidal activity combined with warming will bring these coastline and seafloor deposits to the mix.  Since methane has approximately 20-23 times greater impact on warming, meaning it traps much more heat, the ramifications of large scale emissions of methane into the atmosphere further exacerbate the positive feedback loop.  Because methane dissipates relatively quickly, the overall impact of methane release may not have enormous impact on overall global average temperatures (Kvenvolden, 1988) in and of itself, taken together with other components of a positive feedback loop, the impact could be magnified.

If technology existed to easily capture methane from the Arctic tundra, the sheer quantity of deposits might help to accelerate the economic viability of methane production.  Because it is a very efficient fuel, there is little doubt that an economic model to capture methane would be of serious interest to the Arctic and to stakeholders in the Arctic, especially those who would be in a position to benefit from resource development. 

Capturing the methane before it escapes into the atmosphere would prevent a GHG some 20+ times as potent as CO2 from contributing to climate change, but the climate ramifications of getting to the resource and how it would be combusted would still have an impact, so it would be at a net cost to the environment, but that net would be somewhat less than simple emission.

Works Cited

Michaels, P., 2004. The Economist; A canary in the coal mine. [Online] 
Available at: http://www.economist.com/node/3375415
[Accessed 19 01 2013]
NSIDC, 2012. Arctic Sea Ice News and Analysis. [Online] 
Available at: http://nsidc.org/arcticseaicenews/
[Accessed 02 09 2012]
Hinzmon, L. D., 2005. Evidence and Implications of Recent Climate Change in Northern Alaska and Other Arctic Regions. [Online] 
Available at: http://link.springer.com/article/10.1007%2Fs10584-005-5352-2?LI=true
[Accessed 28 12 2012]
Callaghan, T. V. et al., 2010. A new climate era in the sub-Arctic: Accelerating climate changes and multiple impacts. Geophysical Research Letters, 37(14)
Zwally, H. J. et al., 2002. Surface Melt-Induced Acceleration of Greenland Ice-Sheet Flow. Science, pp. 218-222
McConnell, J. R. e. a., 2007. 20th-Century Industrial Black Carbon Emissions Altered Arctic Climate Forcing. Science, 317(7 September 2007), pp. 1381-1384
Kvenvolden, K. A., 1988. Methane hydrate — A major reservoir of carbon in the shallow geosphere?. Chemical Geology, 71(1-3), pp. 41-51

No comments:

Post a Comment