Balancing the New Zealand Carbon Budget

unfccc copyTwenty three years ago today, the UN framework Convention on Climate Change was completed for signing.  In those last twenty three years, New Zealand has spent its carbon budget like a drunken sailor.  In just two years, New Zealand will have exceeded the lower limit for our share of the global CO2e emissions we cannot exceed if we are to have a 2 in 3 chance of avoiding 2 degrees of global warming.   Kiwis have both the major parties- National and Labour to thank.

Anyone can confirm whether this is true or false by doing the arithmetic using the figures from the IPCC.  According to the IPCC’s Fifth Assessment report published in 2014, to achieve a “likely” (66% or better) probability of avoiding 2 degrees of global warming,  global cumulative emissions must not exceed 550 to 1300 Gt CO2e  by the agreed on date of 2050. [IPCC2014]

Characteristics of modelled scenarios assessed for IPCC Fifth assessment Report, 2014.

Characteristics of modelled scenarios assessed for IPCC Fifth assessment Report, 2014.

What is New Zealand’s carbon budget for this period, and what is necessary to stay within that budget?
1) With our population representing .06% of the global population [NZStats01], our share of the remaining of the two degree global CO2 equivalent budget is .06% of 550 to 1300 Gt = 348,364 to 823,405 gigagrams CO2e.  For a two out of 3 chance of avoiding 4 degrees of global warming, the limit is 994,420 to 1,228,774 gigagrams.

2) Assume NZ achieves the Green policy target of zero net CO2e emissions by 2050. According to the Ministry for the Environment, our net yearly expenditure as of 2012 was 49,450 gigagrams per year [MFE2014], so this would mean that if we started reducing today, we would have to reduce by 1,374 gigagrams per year.

3) Chart the reductions in a spreadsheet. If we assume the models that give New Zealand the greatest amount of time, even if we adopt the Green Climate Change policy, NZ will blow its two degree carbon budget before the end of 2029.  This is 21 years ahead of schedule. If we assume the model that is the least permissive, we will blow our budget in just two years- 2017.

4) For New Zealand to do its fair share of CO2e emissions reductions, we either must 1) accelerate our target date for net zero emissions to a date much earlier than 2050, or 2) must massively accelerate our sequestration capacity to bring our net CO2e emissions into negative territory to make up for our overspending.  As of the date of this writing the Greens have not specified how they propose to bring the New Zealand Carbon Budget into balance by 2050.

Year CO2e Net GigaGrams Total
2011 49,450 49,450
2012 49,450 98,900
2013 49,450 148,350
2014 49,450 197,800
2015 49,450 247,250 Assume reductions begin.
2016 48,076 295,326
2017 46,703 342,029 Blow 2° carbon budget if most grim IPCC model is used.
2018 45,329 387,358
2019 43,956 431,314
2020 42,582 473,896
2021 41,208 515,104
2022 39,835 554,939
2023 38,461 593,400
2024 37,088 630,488
2025 35,714 666,201
2026 34,340 700,542
2027 32,967 733,508
2028 31,593 765,101
2029 30,219 795,321 Definitely blow 2° budget (upper limit exceeded)
2030 28,846 824,167
2031 27,472 851,639
2032 26,099 877,738
2033 24,725 902,463
2034 23,351 925,814
2035 21,978 947,792
2036 20,604 968,396
2037 19,231 987,626 Blow NZ budget lower bound for 4° warming
2038 17,857 1,005,483
2050 1,374 1,112,625

Disclaimers: Although these calculations are based on authoritative figures, the calculation is original research and as of this date has not been independently assessed for accuracy.


[IPCC2014]  IPCC, 2014: Summary for Policymakers, In: Climate Change 2014, Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. [find it here] See page 13, table 6.5.

[PopStats] Unrounded NZ percentage of global population .0633%  New Zealand Population clock as of 9 May 2015: 4.587 million

World population 7.242 billion according to US Census

[MFE2014]  “New Zealand’s total greenhouse gas emissions were 76,048.0 Gg CO2-e in 2012″, page v. report:”New Zealand’s Greenhouse Gas Inventory 1990 – 2012”

Updates: 10 May 2015, added disclaimer, UNCCC logo, correction of typo, clarified nature of anniversary- It is not the date the treaty was signed: the actual “signing” took place over an extended period.  The date of 9 May 1992 is when the treaty was complete (in UN parlance, the date the convention was “adopted”).  It was first “opened for signing” in Rio de Janeiro from 4 to 14 June 1992.  My thanks to David Tong for the correction.

16 September 2015, Updated the table to use net emissions including land use.


About John JMesserly

Mostly harmless

Posted on 2015-05-09, in Uncategorized. Bookmark the permalink. Leave a comment.

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