Carbon Sequestration
Carbon sequestration refers to the capture and long-term storage of carbon in forests and soils or in the oceans, so that the build-up of carbon dioxide (one of the principal greenhouse gases) in the atmosphere will reduce or slow. Managing land and vegetation to increase carbon storage can buy valuable time to address the ultimate challenge of reducing greenhouse gas emissions.
Article 3 of the Kyoto Protocol allows for the offset of emissions by investing in activities that increase carbon sequestration. This would generally involve an investor or buyer being issued with "carbon credits" corresponding to the amount of carbon sequestered by these activities. These credits could then be used to offset part of the buyer's net greenhouse gas emissions (for example from their electricity or steel manufacturing plant). This provides a relatively low-cost opportunity for the private sector to reduce emissions while promoting a comprehensive and environmentally responsible approach to climate change.
There are three main types of carbon sequestration:
Carbon sequestration in terrestrial ecosystems - Increasing the amount of carbon stored in vegetation and soils;
Carbon Sequestration in the Oceans - Enhancing the net uptake of carbon from the atmosphere by the oceans, through fertilisation of phytoplankton with nutrients and injecting carbon dioxide to ocean depths great than 1000 meters; and
The subsurface sequestration of carbon dioxide in underground geological repositories.
All of these options are commonly known as carbon "sinks". The first, increasing carbon storage in terrestrial ecosystems, is currently the focus of the most attention and is the easiest and most immediate option at the present time. The other options may become more important in the future, as the science and legal systems develop.
Increasing carbon storage in terrestrial ecosystems
Plant growth occurs through the process of photosynthesis, during which carbon is captured and stored in plant cells as the plant grows. Over time, branches, leaves and other materials fall to the ground, gradually losing their stored carbon back to the atmosphere as they decompose. A portion of the carbon from this decomposing plant litter may sometimes be captured by organisms living in the soil, or through processes involving plants' root systems.
The terrestrial ecosystem currently sequesters carbon at a rate of about two gigatonnes each year (2 GtC/year). With careful management, this could be significantly increased by several gigatonnes per year, providing a critical period of "bridging technology" while other carbon management options are developed.
Carbon sinks in this category may be living, aboveground biomass (eg. trees), products with a long, useful life created from biomass (eg. timber), living biomass in soils (eg. roots and microorganisms), or organic and inorganic carbon stored in soils and deeper subsurface environments.
Eligibility of carbon sequestration credits
At the most recent Conference of the Parties (COP) held in Marrakesh in late 2002, the Parties agreed to define "afforestation", "reforestation" and "deforestation" under Article 3.3 on the basis of a change in land use. The COP also agreed that eligible activities under Article 3.4 of the Protocol are:
Forest management;
Cropland management;
Grazing land management; and
Revegetation.
Parties may choose to apply any or all of these activities during the first commitment period (2008-2012). These activities will not account for emissions and removals resulting from afforestation, reforestation and deforestation as under Article 3.3.
To be eligible for carbon credits, these activities must be shown to have been human induced, to have resulted in a net sequestration of carbon, and to have taken place since 1990. Credits will be based on the change in carbon "stocks" (ie. volumes of carbon stored) during the "first commitment period" under the Kyoto Protocol, which runs from 2008 to 2012.
At this time, it is contemplated that carbon sequestered after 2012 will become part of a subsequent commitment period under the Protocol, with even lower targets for participating countries. It remains to be seen whether or not such a subsequent period will be agreed to, however.
It is important to note that non-tree species, previously excluded from the Kyoto Protocol, are now included in the list of plants that will be able to be counted as carbon sinks. This is particularly important for Australia, as it will allow the carbon sequestered in shrubs and bushes in arid rangelands to be counted as carbon credits.
The industry is now focussed on developing and standardising methodologies that will translate farm, scrubland and forest systems to carbon sequestration rates.
The following accounting rules were established:
net emissions or removals over the commitment period less net removals in the base year, times five for agricultural activities (cropland management, grazing land management and revegetation);
accounting for forest management up to the level of any possible Article 3.3 debits, if the total carbon stock change in the managed forests since 1990 is equal to or larger than this Article 3.3 debit;
additions to and subtractions from the assigned amount of a party resulting from forest management under Article 3.4 after the application of the Article 3.3 debit compensation described above, and resulting from forest management undertaken under Article 6 shall not exceed the value inscribed to each country in Appendix Z.
Though no overall cap on sink credits was established, reliance upon use of sinks in CDM activities will be limited to afforestation and reforestation during the first commitment period.
