The basic message of the report is that forests, agricultural ecosystems (primarily soils) and wetlands are critically important ecosystems for soaking up carbon. Conversely, if destroyed, they can be an equally important source of carbon leakage into the atmosphere. By safeguarding natural ecosystems and improving or restoring damaged agricultural ecosystems, there is potential to prevent well over 50 gigatonnes (Gt) of carbon entering the atmosphere per year.

Deforestation contributes about 15% of human-caused carbon emissions each year. Drainage of peatland for agriculture releases another 2%.   According to the report, the value of peatland for locking up carbon far outweighs the carbon benefits of the biofuel crops for which it is cleared. For example, the combustion of palm oil produced on drained peatland equates to a carbon 'debt' which could take centuries of biofuel production to repay. 

In terms of agriculture, best management practices could save about 11 to 12% of human-produced CO₂ equivalent per year by 2030, mainly by conserving soil and increasing its capacity to absorb carbon. 

These estimates are for agriculture as practiced in Europe, where cropping and horticulture are more common than in New Zealand.  The same estimates may not apply to New Zealand, where livestock farming is more common and cropping and horticulture are less so.  However, even in New Zealand, agriculture has potential to greatly reduce its contribution to global warming.  The amount of methane produced by livestock varies significantly depending on the type and quality of feed that animals are fed, and on the genetically-based efficiency of their metabolism.  Methane is a greenhouse gas that is many times more potent than carbon.  With appropriate pasture and feed management, the methane produced by livestock can be greatly reduced. Furthermore, New Zealand soils are heavily compacted and damaged by current dairy farm practices while dry stock farming is a significant contributor to the loss of hill country soils from erosion.   In terms of global warming New Zealand agricultural practices could be improved by reducing stock numbers (fewer high-producing stock), reducing the use of artificial fertilizers (particularly nitrogen), better breeding and feed management of stock, better matching of land use capability to type of land use (so that heavy beef or dairy cows are not pastured on erodible land) and changing land use from livestock to forestry or agro-forestry (mixed agriculture and forestry).  In the long-view, given that all forms of meat and dairy involve higher carbon emissions per calorie than vegetables and fruit, the optimum land use for most of New Zealand’s exotic (i.e. non-native) landscapes is probably one of forestry on the hill slopes and crops, orchards and horticulture on the flat lands. 

The report suggests that the management of carbon storage and uptake is achievable if the right policy framework is in place. However, there is uncertainty about the amounts of carbon that can be sequestered by trees and soils, and the authors note that all stores, except perhaps peat, would eventually reach saturation.

It is worth noting that while the International Panel on Climate Change (IPCC) has concluded that an appropriate price for carbon is €70 per tonne of CO₂ or about NZ$140 per tone, recent New Zealand government policy– as reflected in its Climate Change Response (Moderated Emissions Trading) Amendment Bill is built on an assumption of $25 per tonne of carbon.  If agriculture, transport and energy are to be charged $25 per tonne for their carbon pollution and the international cost is close to NZ$140, the New Zealand taxpayer will face the cost of paying the rest. 

See: http://ec.europa.eu/environment/climat/climate_action.htm

Source: United Nations Environment Programme report. (2009). The Natural Fix? The Role of Ecosystems in Climate Mitigation. A UNEP Rapid Response Assessment. Download from: http://www.unep.org/publications/search/pub_details_s.asp?ID=4027