Like what you've read?

On Line Opinion is the only Australian site where you get all sides of the story. We don't
charge, but we need your support. Here�s how you can help.

  • Advertise

    We have a monthly audience of 70,000 and advertising packages from $200 a month.

  • Volunteer

    We always need commissioning editors and sub-editors.

  • Contribute

    Got something to say? Submit an essay.


 The National Forum   Donate   Your Account   On Line Opinion   Forum   Blogs   Polling   About   
On Line Opinion logo ON LINE OPINION - Australia's e-journal of social and political debate

Subscribe!
Subscribe





On Line Opinion is a not-for-profit publication and relies on the generosity of its sponsors, editors and contributors. If you would like to help, contact us.
___________

Syndicate
RSS/XML


RSS 2.0

It ain't necessarily so on sea rise

By Mike Pope - posted Tuesday, 16 August 2016


3. As surface permafrost melts it produces a landscape which is largely waterlogged since lower, intact permafrost inhibits drainage resulting in formation of thermokast lakes. This creates anoxic conditions essential for methanogens to produce CH4 from biota but inhibit oxidation by methanotrophs. Release of carbon from waterlogged land surfaces is likely to be in the form of CH4 rather than >95% CO2 predicted by some.

Fig. 2. Comparison between atmospheric concentration of CH4 and CO2 over the last 400,000 years and their effects on average global temperature to 2013. While most CH4 emissions result from human activity, mining and animal husbandry, emissions associated with permafrost degradation are increasing. Source: R.Morrison, Wikipedia

Advertisement

Analysis of foraminifera and Antarctic ice cores show that globally, CH4 concentration in the atmosphere is now at its highest level in over 800,000 years. What makes present levels so dangerous is that studies by Reisinger et al (2011) show that over a 20 year period, CH4 now has radiative forcing properties 84 times greater than CO2, a finding accepted by 5AR. Yet the 5AR dismisses the notion that CH4 emissions from Arctic continental shelves and adjacent onshore areas contribute to Arctic amplification or that this contribution can, let alone will, rapidly accelerate permafrost degradation and larger CH4 releases this century.

The result of underestimating CH4 emissions in the Arctic and their GWP makes it likely that the 5AR significantly underestimates Arctic amplification, loss of ice mass from the GIS, consequent sea level rise this century and the speed with which sea ice covering the Arctic Ocean reduces.

Albedo Loss

The 5AR defines an ice-free Arctic Ocean as sea ice extent less than 1 × 106km2for at least 5 consecutive years (5AR Ch. 11.3.4.1)and asserts that these conditions could pertain by summer 2050 (5AR Ch. 2, Fig. 2.1.b) and that consequential loss of albedo will have an important (though unquantified) effect on ocean warming, accelerating ice loss, coastal erosion and permafrost degradation. Most scientists would agree, though many are of the view that the Arctic Ocean will be ice free in summer long before 2050, possibly as soon as 2030. The 5AR is seen by many as underestimating Arctic Ocean warming, loss of sea ice and albedo.

Relatively rapid loss of sea ice, combined with ingress of warmer water from the Pacific and Atlantic will reduce formation of multi-year sea ice, making the Arctic coastline vulnerable to erosion, exposing carbon bearing ice and biota to a warming atmosphere. This is likely to result in greater release of CH4 as sub-surface ice containing biota are exposed to methanogens.

Advertisement

Fig. 3 Soot and aerosols produced by human activity and from natural sources contribute to atmospheric warming and when they settle on ice in the Arctic, absorb solar energy which accelerates melting. Source: Arctic News/Dark Snow Project.

Aerosol soot in the Arctic originates in human activity and, as the climate warms, a rising incidence of forest burning. It falls over a vast area of the Arctic covering large areas of sea ice and the GIS. This reduces albedo and increases absorption of solar radiation, thereby accelerating seasonal melting, increasing mass ice loss

since 2000. In the case of the GIS, surface melting produces lakes which ultimately flow to the ice sheet base, lubricating the land surface on which its rests before flowing to the ocean, enhancing ice sheet mobility.

  1. Pages:
  2. 1
  3. 2
  4. Page 3
  5. 4
  6. 5
  7. All


Discuss in our Forums

See what other readers are saying about this article!

Click here to read & post comments.

27 posts so far.

Share this:
reddit this reddit thisbookmark with del.icio.us Del.icio.usdigg thisseed newsvineSeed NewsvineStumbleUpon StumbleUponsubmit to propellerkwoff it

About the Author

Mike Pope trained as an economist (Cambridge and UPNG) worked as a business planner (1966-2006), prepared and maintained business plan for the Olympic Coordinating Authority 1997-2000. He is now semi-retired with an interest in ways of ameliorating and dealing with climate change.

Other articles by this Author

All articles by Mike Pope

Creative Commons LicenseThis work is licensed under a Creative Commons License.

Article Tools
Comment 27 comments
Print Printable version
Subscribe Subscribe
Email Email a friend
Advertisement

About Us Search Discuss Feedback Legals Privacy