The second aspect of the debate is market differentiation, whereby countries, regions or companies try to prove their product is better or 'greener' than others.
There are no clearly defined rules or global standards here and it is mainly marketers that seek to gain advantage through 'carbon footprints' or 'carbon-neutral' products.
For Irish agriculture, the legal requirement to reduce CO2 emissions will be the most challenging.
This requirement includes reductions in methane and nitrous oxide, calculated as CO2 equivalents, produced from agriculture. Unfortunately, nitrous oxide is potent and when converted into CO2 equivalents, results in high emissions figures being associated with agricultural production.
There are strong arguments that agriculture should benefit from the absorption of CO2 by plants, thereby offsetting the emissions from soil and animals. However, scientists argue that plants release CO2 when harvested, so only long-life plants such as trees should be included in calculations.
This process is known as carbon sequestration and could be an important consideration in achieving Ireland's reduction commitments.
But this is not a simple process and opens a debate on which method should be used to calculate Ireland's overall emissions. We need to be careful in selecting the appropriate method of calculating our overall emissions so that we do not end up with a system that is overly cumbersome to manage.
For Irish agriculture, the immediate consideration is how these emission reductions will be achieved. Debates over inclement weather being positive proof of climate change are not relevant; only history will provide the evidence.
The reduction commitments are real and are, as a result of political agreement, binding. Therefore, we need to focus on how emissions can be reduced while trying to increase productivity and output in line with the predictions of Food Harvest 2020.
Opinions vary on the actions necessary to achieve these emission reductions. Extremists propose that consumers should eat less meat and dairy products and opt rather for vegetarian diets. Others suggest that Ireland, as a surplus producer, can afford to reduce agricultural output.
The moderate view is that reductions can be achieved through actions such as reduced fuel usage, minimum tillage systems, reduced fertiliser usage by increased clover use, promoting higher genetic merit beef and dairy animals, longer lactation periods and diet manipulation.
What is not known is what reductions could be achieved if these practices were immediately implemented on all Irish farms? This poses the question: Why was political agreement on emission reductions reached before this potential reduction was calculated?
The second aspect of climate change, whereby we seek to differentiate Irish food production as the most sustainable, is more readily achieved.
Sustainability in agricultural production is made up of many elements such as economic sustainability, environmental sustainability, air emissions, water quality and management, soil management, biodiversity and animal welfare.
This is where Ireland can seek to differentiate itself in marketing its produce, and a collective approach in achieving this must be a priority for the industry. Many of the recommendations of Food Harvest 2020, if implemented, can be important in reinforcing this position.
The 'brand Ireland' concept, as presented in the food harvest report, can be an important element in positioning Ireland as a sustainable producer of food and drink.
Brand Ireland must begin with the development of credible sustainability metrics that stand up to the scrutiny of international competitors, who will similarly seek to position their produce as sustainable.
It must achieve this not through the development of costly farm-by-farm audit systems, but through a practical linkage with existing measures and systems at farm level.
For example, herd reports generated through ICBF could be mined for additional information that can be used for sustainability purposes. Similarly, Teagasc farm-monitoring systems are equally valuable in providing information to support the sustainability aspect of brand Ireland.
The priority must be to begin by using the available data that is being collected at farm and processor level, and then using this to feed into the metrics that will reinforce the sustainability element of brand Ireland.
We must, however, recognise that, as a nation of exporters, we must deliver what our market requires. In terms of sustainability, this often means that we need to use sustainability metrics of customers that do not always allow us to position our products as we would like.
For example, many global retailers apply metrics that enable intensive dairy systems to ignore the impact of imported feedstuffs. This gives an immediate advantage to high input production systems over our more natural production system, where the impact of domestically grown feedstuffs is included.
Graphs one and two (opposite page) show that the level of greenhouse gas emissions per litre of milk can be dramatically different, depending on the method of calculation used.
Graph one shows the greenhouse gas emissions per litre of milk when all factors in the cow's life are taken into account. This covers emissions from birth to rearing, calf production and all other activities in her life.
However, Graph two shows the greenhouse gas emissions per litre of milk when only the digestion of the cow is taken into account.
As you can see, the different calculation methods significantly alter the ranking of the countries. For example, New Zealand has the lowest emissions per litre of milk when all factors from the cow's birth to the end of her productive life are calculated. When only digestion is taken into account, the UK has one of the lowest emission figures and New Zealand has one of the highest tallies.
As we encounter an ever-increasing number of different metrics, each measuring different things, there is a clear case for a single global standard that is consistent with that used for the legal reduction agreements.
A global standard would be an important step in taking cost and inconsistency out of a system that is already complex.
For Ireland's dairy industry, there is clearly work ahead. The legal requirement to reduce our overall emissions is the most pressing and Teagasc has already assembled a large team to assist in this process.
This will present challenges, but is a crucial element in ensuring that we can realise the growth potential of the industry. The marketing opportunities for Ireland as a sustainable place for food production are clear.
There is a balance between differentiating Ireland and seeking a single global standard to avoid a high-cost system where every customer demands its own metrics and audits.
But, wherever this debate moves, the focus must always be on sustainable food production and every effort made to ensure that climate change does not become an excuse for other interest groups that would seek to undermine Ireland's natural system of food production.