Warming in the Arctic

Originally written by Sam Carana in December 2011 (updated January 2012) as a post at knol. When knol became discontinued, the post was preserved at the Arctic-news blog as a page, for archival and reference purposes, with a slight update in March 2012. Some of the images are described that also featured in the poster displayed at AGI 2011.  

Pollutants in the atmosphere and oceans have reached such proportions that a confluence of events is now threatening to dramatically aggravate the situation and result in catastrophe at a scale unprecedented in human history.

One event is the warming in the Arctic as a result from emissions. A second event is the disappearing sea ice. The associated albedo change means that much more sunlight will instead be absorbed in the Arctic, accelerating the warming that is already now occurring at much faster rates than elsewhere in the world. A third event is an increase in the release of methane in the Arctic. These three events are pictured below:

1. Emissions are causing climate changes around the globe, and the Arctic is particularly vulnerable. Ocean currents and rivers feed warm water into the Arctic Ocean. On land, thawing permafrost threatens to release additional greenhouse gases at rates not foreseen by the IPCC. Droughts and heatwaves threaten to trigger wildfires that can rage fiercely in peatlands and tundras at higher latitudes, with little or no prospect of recovery of such ecosystem in the near future.

2. In addition, the Arctic is particularly vulnerable to soot that is emitted globally and can settle down on Arctic ice, causing albedo changes. This contributes to the accelerated warming in the Arctic that causes sea ice loss, which creates a feedback that causes further albedo changes, in a vicious cycle further accelerating warming in the Arctic.

Above chart, by Wipneus based on PIOMAS data, shows the dramatic loss of Arctic sea ice. Without sea ice, less sunlight will be reflected back into space (albedo change). As the sea ice disappears, it no longer acts as a buffer that holds the energy that previously went into melting the ice.

As the sea ice heats up, 2.06 J/g of heat goes into every degree Celsius that the temperature of the ice rises. While the ice is melting, all energy (at 334J/g) goes into changing ice into water and the temperature remains at 0°C (273.15K, 32°F). Once all ice has turned into water, all subsequent heat goes into heating up the water, at 4.18 J/g for every degree Celsius that the temperature of water rises.
As the image shows, the amount of energy absorbed by melting ice is as much as it takes to heat an equivalent mass of water from zero to 80°C. As the ice disappears, this energy will cause temperatures to rise in the Arctic.
3. A third kind of warming comes from methane releases from melting permafrost and submarine hydrates. This adds a further feedback contributing to accelerated warming in the Arctic. Altogether, these three kinds of warming combine to cause the Arctic to warm up much more vigorously than elsewhere on Earth. Due to oxygen depletion in the shallow waters of the Arctic and the lack of hydroxyl in the Arctic atmosphere, this methane, with its high initial warming potential, now threatens to escalate into runaway global warming.

The chart on the left, based on historic NASA land-surface air temperature anomaly data (see interactive map at the bottom of this page), shows that the average temperature anomaly rise in the Arctic (latitude 64 and higher) looks set to reach 10 degrees Celsius within decades.

These anomalies are based on annual averages that are also averaged over a huge area.
The NASA image of the globe on the left shows temperature anomalies of over 10 degrees Celsius for December 2011.

Over December 2011, an average temperature anomaly of 12.8933 degrees Celsius was recorded in an area in the Kara Sea (latitudes 79 - 81 and longitudes 73 - 89).

The animated image below, based on NOAA data for the period December 7, 2011 - January 21, 2012, shows that specific areas can already experience anomalies of over 20 degrees Celsius for specific days. (Note: this is a 3MB file that may take some time to fully load.)

For individual days and locations, the anomaly can be even more striking. On January 6, 2011, the minimum temperature in Coral Harbour, located at the northwest corner of Hudson Bay in the province of Nunavut, Canada, was –3.7°C (25.3°F), i.e. 30°C (54°F) above average.
The danger is that very high peak temperature anomalies can be expected in methane hotspot areas. Above temperature anomalies have yet to incorporate the full impact of the various feedback effects. 

As an example of such feedbacks, as the sea ice retreats, sunlight that was previously reflected back into space will get absorbed in the Arctic. Furthermore, various studies have found an accelerating frequency and intensity of storms in the Arctic, attributed to progressively warmer waters. As the sea ice decreases, the larger area of open water allows for even larger storms to develop, which could erode coastal soils, cause landslides and destabilize methane hydrates, resulting in large abrupt methane releases with a high warming potential.

Methane is predominantly broken down by hydroxyl. The IPCC gives methane a lifetime of twelve years. However, more methane causes hydroxyl depletion and methane levels in the atmosphere are already such that they have caused a 26% decrease in hydroxyl. In the Arctic, where hydroxyl levels are already very low, this situation looks set to deteriorate even further. 

At the moment, the sea ice reflects light, helping formation of hydroxyl through tropospheric photolysis. Once the sea ice is gone, more light will instead get absorbed in the Arctic. One study projects that this can cause late-summer hydroxyl concentrations to decrease by up to 60% in an ice-free Arctic.

The danger is that if relatively large amounts of methane are released abruptly into the atmosphere in the Arctic, they will persist for decades, triggering yet further temperature rises and methane releases, in a vicious cycle leading to runaway global warming, even if the world did manage to take the necessary steps to dramatically reduce emissions.

Above image illustrates how much organic carbon is present in the melting permafrost. The recent firestorms in Russia provide a gloomy preview of what could happen as temperatures keep rising in the Arctic. Much of the soot from firestorms in Siberia could settle on the ice in the Himalaya Tibetan plateau, melting the glaciers there and causing short-term flooding followed by rapid decrease of the flow of ten of Asia’s largest river systems that originate there, with more than a billion people’s livelihoods depending on the continued flow of this water.

All this calls for a comprehensive plan of action that includes geo-engineering.

- Three kinds of warming. Image created by Sam Carana (2011), based on earlier version that was part of a poster displayed at AGU 2011:  
http://eposters.agu.org/files/2011/12/Poster-2.pdf  (link meanwhile discontinued)

- NASA Study Finds Rising Arctic Storm Activity Sways Sea Ice, Climate Gretchen Cook-Anderson, NASA (2008) 

- Graph with Exponential Trend added by Wipneus to PIOMAS data: 
Yearly Minimum Arctic Sea Ice Volume Data, from Polar Science Center | Applied Physics Laboratory | University of Washington (2011) http://psc.apl.washington.edu/wordpress/research/projects/arctic-sea-ice-volume-anomaly/

- Interactions with Aerosols Boost Warming Potential of Some Gases Leslie McCarthy, NASA (2009) 

- How different would tropospheric oxidation be over an ice-free Arctic? Voulgarakis et al. (2009) http://www.agu.org/pubs/crossref/2009/2009GL040541.shtml  

- Arctic temperature rise, image created by Sam Carana (2011), based on NASA data (see interactive map below) and part of a poster displayed at AGU 2011:  
http://eposters.agu.org/files/2011/12/Poster-2.pdf  (link meanwhile discontinued)

- Global Warming Potential, IPCC (2007)

- EUR 21855 EN - soil organic carbon European Commission (2011) http://ies.jrc.ec.europa.eu/uploads/fileadmin/Documentation/JRC-CC-COP17.pdf.pdf

1 comment:

  1. Fascinating post. You might be interested in the albedo feedbacks related to supraglacial microbial activity, which are fast becoming recognised as potential climate amplifiers.

    Thanks for keeping the great blog, this is a really useful resource!