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Carbon auditing and sequestration

Carbon auditing

Carbon auditing is the term give to the process of calculation the carbon balance (carbon sequestered versus carbon emitted) of a given activity, organisation, or geographical region. Normally the balance is expressed in units of carbon dioxide and includes all greenhouse gases expressed in equivalent tonnes of carbon dioxide (tCO2e). The term carbon accounting is sometimes used instead.

Carbon sequestration

Carbon sequestration refers to the capture and removal of carbon dioxide from the atmosphere by means of biological, chemical or physical processes in order to help mitigate global warming. The simplest method is to plant trees, which take up atmospheric carbon dioxide as part of the process of photosynthesis and with the addition of water convert this into sugar and oxygen for growth. The residual carbon becomes locked up in the complex organic compounds which form the cellular structure of the tree, where it remains until the tree dies and decays (or is cut down for fuel or some other use). Thus a long-lived tree can lock up significant quantities of carbon for hundreds of years. Potentially, if sufficient trees were planted global warming could be halted or possiby even reversed. However, the actions associated with preparing ground for planting trees also release carbon dioxide from the soil and in the worst cases - particularly where trees are planted on bog (peat) - carbon sequestration becomes negative (in other words there is a net increase in atmospheric carbon dioxide). In order for carbon sequestration to be accurately assessed, all loses and gains must be properly accounted for.


Carbon offsetting

Carbon offsetting refers to the process whereby greenhouse gas emissions are deemed cancelled out by virtue of carbon sequestration/reduction undertaken elsewhere. For example, some airline companies claim the greenhouse emissions attributable to their flights are offset by tree planting they have arranged to take place in the developing world, claims which may help asuage feelings of guilt in their passengers but which may not be verifiable

In practice offsetting claims are rarely scutinised to the degree necessary to verify their potential authenticity (and such scrutiny would need to be repeated on a regular basis to ensure the offsetting projects were being properly managed). The reality is that most carbon offsetting amounts to little more than clever PR aimed at improving the image of an activity incompatible with greenhouse gas emission reduction objectives.


Medieval indulgences

Carbon offsetting can be compared to medieval indulgences, whereby sinners could redeem their otherwise unpardonable acts by making a donation to the church of a size appropriate to their sins. Indulgences could even be used to cancel out future sins, thereby guaranteeing a purgatory-free afterlife. Unfortunately this sort of cute trickery doesn't really work with global warming.


Carbon offsetting scams

Carbon offsetting scams represent a clever way for large carbon emitters to improve their public image and are big business! The most common ones involve projects that have already happened: for example the client B buys a piece of existing mature forest from Client A. But if this forest is used to offset the client B's future emissions it just means that emissions arising from client A - the previous owner - are no longer offset. For both client's emissions to be offset, additional trees would have to be planted.

Another type of scam involves the alleged planting of trees in some corrupt and impoverished developing country, where no proper auditing or inspection of the project takes place and where endemic fuel poverty, political insecurity and corruption make it highly likely that the trees - if even planted - won't make to it to an age when appreciable amounts of carbon will be sequestered. The amounts of carbon sequestration attributed these project is often calculated on thhe basis all trees planted will survive and develop into mature trees, which in the real world just never happens (apart from anything else the trees will require thinning). In other cases tree planting associated with corporate sequestration projects has involved the seizure of land from indigenous people, eviction of tenant farmers and a host of human rights abuses.


Double counting

This is a type of fraud frequently perpetuated in carbon offsetting whereby the carbon sequestered is counted more than once, as in cases similar to the one above, where the carbon sequestered is claimed by both client A and client B (and probably claimed a third time by the intermediary C who set the deal up).


Deliberate omission or under-representation of carbon costs, or overestimation of benefits

These are frauds or misrepresentations endemic in carbon auditing, in particular by organisations with vested interests coniferous forestry plantations (for example the Irish state).

Two of the primary misrepresentations are given below:

1 Underestimatation of emissions associated with land preparation

In spite of claims to the contrary, conifers continue to be planted on bog (peat). The drainage and clearance work associated with preparation of bog for planting conifers causes the release of considerable quantities of carbon dioxide, which in worst cases could be more than the uptake by the trees (particularly if harvested young)

2 Overestimation of long term sequestration

2a overestimation of total biomass

This is frequently done, simply by cherry-picking data from that which shows the highest biomass gain (for example trees grown on bog in optimum climatic conditions, or from hypothetical cases where long term forest management is close to best practice)

2b overestimation of the portion of total biomass with potential for long term sequestration

For sequestration to be genuine, the carbon needs to be locked up for a minimum of 50 years (and preferably twice that), either in living matter or harvested product, or in stable organic compounds in soils. The proportion of total biomass actually harvested typically ranges from 60-70%, the balance of 30-40% being left behind in the clear fell as roots, stumps, small branches and needles. Most of this will rot down within 20 years, with the majority of carbon being released into the atmosphere as carbon dioxide.

Of the harvested proportion, only about 15% (approx 9-10.5% of total biomass) ends up as construction timber (and a proportion of this would be unavoidable wastage in the form of damages,construction errors or offcuts) . A further 20% (12-14% of total biomass) is used for fence posts and pallet construction, where its life would be short. 55% (33-40% of total biomass) is used for board construction (MDF, OSB and chipboard), a portion of which - perhaps one half - can be assumed to have a lifespan similar to the construction timber, the balance destined for short term uses such as hoarding, packaging, sign-boards, form-work, low cost furniture and partitions.

Most of the remainder of the harvested biomass is burnt as fuel where the carbon is immediately release to the atmosphere.

At best, 30-35% of the original biomass would have a long term carbon sequestration benefit. However typically speaking, figures quoted by the conifer industry imply 70-100% long term sequestration, which simply isn't the case.


Omission of feedbacks arising from changes in land use/vegetation cover

A further important omission in the claims made of coniferous forestry is the change in global warming potential of land planted in conifers. Compared to most other vegetation types, conifer needles are dark and have a low albedo, meaning they increase the potential for absorption of solar radiation at the earth's surface. Land planted in conifers will warm more strongly than grassland or land planted in broadleaves, and any claimed benefit in carbon sequestration needs to be adjusted downwards to allow for this. In many cases, what little long term sequestration benefit exists - once the emissions cost of planting and the low rate of long term biomass utilisation are factored - is likely to be cancelled out. Leaving the land in grassland, allowing it to revert to scrub, or planting it in broadleaves all would be better.


Identifying geniuine carbon sequestration projects involving trees

Do they even exist?? If you think you've spotted one, please let us know!

Possible clues (for genuine biomass carbon sequestration projects):

1 Clear details of what the project entails and its long term aim (for example the establishment of permanent woodland)

2 Clear itemisation of all emissions associated with the establishment and maintenance of the project. Some of these items - for example the emissions associated with land drainage - may be ongoing for many years after the planting has taken place

3 Independently audited annual carbon returns are provided (ongoing emissions versus carbon sequestered)

4 The project is located within a politically stable country, with the land held in trust for a minimum of 50 years)

5 Where biomass is harvested, end use is clearly identified (for example firewood, construction timber, wood chip etc)

The most credible projects will tick at least 4 of these boxes. A project that ticks only 3 boxes is at best borderline. Below 3 boxes and it's probably a scam.


Carbon auditing services

The nursery can advise on carbon sequestration involving woodland projects. Please note we are only interested in working on projects with a lifespan of at least 50 years.