1Watson, R. T. and A. H. Zakri, co-chairs. 2005. Living Beyond Our Means: Natural Assets and Human Well-Being. Statement from the Millennium Ecosystem Assessment Board, p. 5. http://www.maweb.org/documents/document.429.aspx.pdf.

2Philpott, T. 2010. New research: synthetic nitrogen destroys soil carbon, undermines soil health. Grist 23Feb http://www.grist.org/article/2010-02-23-new-research-synthetic-nitrogen-destroys-soil-carbon-undermines-/.

3Gardner, T. 2010. Arctic melt to cost up to $24 trillion by 2050; report. Reuters 5Feb http://www.reuters.com/article/idUSTRE6145M520100205.

4Goodstein, B. 2010. As quoted in Gardner, T. 2010. Arctic melt to cost up to $24 trillion by 2050; report. Reuters 5Feb http://www.reuters.com/article/idUSTRE6145M520100205.

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