Paris emmision


The New Zealand government has been widely criticised by international commentators for its “inadequate” greenhouse gas (GHG) emission reduction target. Tim Groser, the Minister for Climate Change Issues,  justified the Government’s position last month in an address to the Institute of International and European Affairs Leadership Forum on Climate-Smart Agriculture.

The following post provides a critical analysis of the Minister’s address, and in particular, of the Minister’s discussion of agricultural emissions.

Minister Groser argues the UNFCCC fails to adequately consider agricultural emissions, population growth and food security

At the outset, it is important to note that Mr Groser does not “dispute the influence of anthropogenic GHGs on climate change”, rather he opposes the “metrics and methodologies of how to respond [to climate change].” The issue he focuses on in particular is the lack of distinction between carbon dioxide (CO2) and other greenhouse gases, such as methane (CH4), in the UNFCCC draft documents. CO2comprises ~80% of all greenhouse gases in the atmosphere and lasts for hundreds of years, whereas gases from animals, such as methane, are short-lived.

According to Mr Groser, the current method of grouping all GHG emissions together was “developed with industrial emissions by industrial countries in mind.” Agriculture was an afterthought for the nations driving the agreement, such as the USA, who only attribute 7% of their emissions to agriculture. He argues that while New Zealand is currently an outlier, with over half of its GHG emissions attributable to agriculture, by 2050 this will no longer be the case. He contends that the world will need “between 60% and 70% more food by 2050 to feed another 2 billion people” by 2050, primarily in developing nations.

As a result of this growing demand for food, Mr Groser argues that agricultural development on a large scale will be necessary. He contends that the current UNFCCC modalities, which do not distinguish between types of emissions, fail to account for this need, thereby setting up “a binary choice between climate change and food security“. This choice, according to Groser, is one “that cannot be realistically be made in favour of climate change.” He proposes a number of alternate approaches to climate mitigation, which he argues will not de-incentivise food production for developing nations. In particular he suggests:

  • Setting targets around reducing food loss and wastage, since the greenhouse gas footprint of food produced and not eaten is estimated at 3.3 gigatonnes of carbon dioxide equivalents (C02e) – “the third largest ‘emitter’after the US and China.”
  • Upgraded commitments to R&D in reducing methane levels (which is what New Zealand has been doing with the Global Research Alliance on Agriculture Emissions).
  • Putting a price on carbon used in all agriculture processing above a threshold level.

Do the facts and figures check out?

Population projections

The 2015 Revision of World Population Prospects, released in July 2015, is the most recent revision of the official United Nations population estimates and projections.

According to projections in the 2015 revision, the world population of 7.3 billion in July 2015 will increase to 9.7 billion people in 2050, an increase of just under 33%. As with any projection there is an element of uncertainty. The 2015 revision says that it is virtually certain that global population will increase in the short- to medium-term with a 95% chance that global population will be between 8.4 and 8.6 million in 2030, an increase of over 1 billion.


While global population is increasing, the rate at which it is increasing is slowing. Ten years ago, world population was growing by 1.24 per cent per year. Today, it is growing by 1.18 per cent per year, or approximately an additional 83 million people annually. This means there is a 23% chance that global population will stabilise and start to fall before the end of the century. Much of the variance in projections depends on variable fertility rates, with most projections predicting that global population will stabilise after 2100.

Between now and 2050, half of the world’s population growth is expected to be concentrated in nine countries: India, Nigeria, Pakistan, Democratic Republic of the Congo, Ethiopia, United Republic of Tanzania, United States of America, Indonesia and Uganda, (listed according to the size of their contribution to population growth).

In contrast, the largest current populations are set to level out. The population in China and India are currently approximately 1.38 billion and 1.31 billion respectively. India’s population is projected to continue growing for several decades to 1.7 billion in 2050, while the population of China is expected to remain fairly constant until the 2030s, after which it is expected to slightly decrease.

Projections from the Food and Agriculture Organization of the United Nations (FAO) also corroborate Mr Groser’s statements. Feeding a world population of 9.1 billion people in 2050 would require raising overall food production by some 70 percent between 2005/07 and 2050.

Global agricultural emissions

According to the FAO, emissions from the agricultural sector account for roughly 14 percent of global GHG emissions. Most emissions from agriculture (74 percent of the 14 percent total) and most of the mitigation potential of agricultural practices (70 percent) are in developing countries. That is to say, that while agriculture contributes the equivalent 6.8 Gt of COper year to global GHG emissions; it also has the potential to mitigate between 5.5-6 Gt Co2 per year. This supports Mr Groser’s line of reasoning.

Mr Groser concludes that:

In a planet that needs more food not less, policies that simply disincentivise agriculture production would be irrational and unsustainable politically.

Mr Groser is correct that food security will be an on-going challenge, and that limiting food production to reduce emissions may be counter-productive. However, his portrayal of the issue as a “binary choice” is illogical. Adaptation to climate change – including the ability to cope with extreme weather shocks – will be necessary to ensure global food security in both the short and long-term. Adaptation of the agriculture sector will be costly but so will the projected effects of climate change. The issues do not exist in isolation.

The Bigger Picture

Methods of food production

Despite Mr Groser’s accurate statements about rising populations and the growing need for increased food production, his central premise that a distinction between CO2 and methane emissions is required in order to ensure adequate food supply for a growing population is incorrect. While bovine-based food products, such as dairy and beef, are a central part of western diets in particular, they are but one of many agricultural sectors responsible for feeding the growing population. In fact, milk production and cattle farming are among the most unsustainable and energy-intensive methods of food production undertaken globally. Dairy cows and their manure produce high levels of methane, nitrate based fertilisers used to stimulate grass growth degrades local water resources and the dependence on palm kernel for feed promulgates intensive rainforest deforestation, particularly in Latin America.

Thus, while Groser’s statements that a growing population will require a corresponding increase in food supply is correct, his contention that a growing population requires an increase in methane emissions – i.e. through dairy and cattle farming – is not. The challenge of feeding a growing global population requires solutions that are innovative and sustainable, not energy-intensive or wasteful. In particular, strengthening and developing food systems which are comprehensive, sustainable over time and resilient after disasters and crises will be crucial to ensuring food security now and in the future. Dairy and cattle do not provide such a solution.

Impact of methane emissions

Minister Groser stated that:

The real problem in climate change is carbon dioxide from energy and industrial processes. Carbon dioxide, or CO2, comprises some 80% of all greenhouse gases in the atmosphere and worse, stays around for hundreds and hundreds of years, unlike short-lived gases such as methane from animals.

Methane (CH4) has a lifetime of 12 years before being removed from the atmosphere through natural chemical processes, yet this relatively brief existence should not be cause to underestimate its effect. Methane has a higher capacity for trapping heat and thereby introducing energy to the climate system. This means it warms the planet rapidly but dissipates more quickly than carbon dioxide.

Each greenhouse gas has a different capacity for capturing and re‐radiating outgoing infrared radiation in the atmosphere, thereby affecting the energy balance and contributing to climate change. This capacity can be compared in carbon dioxide equivalents (CO2e) and can be represented as its ‘global warming potential’ or GWP. GWPs therefore act as a kind of ‘exchange rate’ for greenhouse gasses, converting them into CO2e in order to compare their climate change impacts.

The IPCC typically publishes GWPs for 20, 100 and 500-year time frames. These time frames are important as a GHG’s impact on the climate changes over time. The GWP of CO2 is always, by definition, one, because it is the reference point for the other gasses.


The table above is taken from the most recent IPCC assessment report (AR5) and outlines the global warming potential of various GHGs in relation to carbon dioxide. It demonstrates that the GWP of methane over a 100 year time frame is 28, meaning the energy methane introduces to the climate system is 28 times that of CO2 over a 100 year period. The GWP for Methane over a 20 year period is 84, indicating that it contributes 84 times more energy into the climate system than an equivalent quantity of CO2. Because of both the large effect that methane reductions can have within 20 years and the serious climate disruption expected in that time (if no significant reduction of GHGs is achieved) the IPCC supports using a 20 year time frame for methane.

The reduction of Methane emissions is potentially a very powerful tool in short-term mitigation. Mr Groser’s assertion of the “absolute primacy of reducing carbon dioxide, above all other gases…” is a limited view that does not acknowledge the need to reduce emissions on all fronts, and specifically downplays the significant role of the agricultural sector in mitigation. He seems to be implying that the agricultural sector should be given some slack in its responsibility to reduce emissions, and that this is justified by the need for food security as global population increases.

While food security and a growing population are critical issues for climate change mitigation and must be considered alongside any proposal to address climate change, Mr Groser fails to acknowledge the critical impact of methane on atmospheric temperature and further ignores the need to develop less energy-intensive agriculture, which can withstand climate shocks and be productive over the long term.

Mr Groser thinks that if mitigation efforts cannot be broadened beyond Annex 1 countries “we are all wasting our time with our own climate change efforts”. In the context of New Zealand’s inadequate commitment ahead of December’s negotiations it is unjustified to point fingers at developing countries when we are failing in our own responsibility to set an appropriate example for those same countries to follow.

What does this all mean for the Paris text?

The draft negotiating text for COP21 does not define greenhouse gases, rather it adopts the broad definition agreed in the 1992 United Nations Framework Convention on Climate Change:

“Greenhouse gases” means those gaseous constituents of the atmosphere, both natural and anthropogenic, that absorb and re-emit infrared radiation.

Given the disproportionate heat-trapping qualities of methane, there is good reason to suggest that it warrants a specific mention in any global agreement on climate change. While “carbon dioxide equivalents” and “carbon dioxide … and other long-lived greenhouse gases” are referred throughout the text, all groupings are very broad and no specific approaches or frameworks in respect of methane or any other non-CO2 GHGs are found anywhere in the text.

Perhaps the distinction between types of GHGs and their respective global warming potentials could be implied, given the UNFCCC’s acknowledgement of the IPCC’s climate assessments. Nevertheless, to avoid confusion, it would be pragmatic to include the distinction specifically in the text, in order to better guide policy proposals suited to different types of emitter nations.

Perhaps, Minister Groser’s suggestions surrounding agricultural strategies – targets on reducing GHG emissions from food loss; carbon from agriculture; and increased R&D around methane – could also be included as additional options in the Mitigation section of the Paris agreement. However, they should remain additional. Agricultural emissions are a critical part of the greenhouse gas equation and any differential approach for agriculture must not selectively ignore the disproportionate heat-trapping qualities of methane.

Written by