科研之友
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摘要
In life cycle assessment (LCA) of paper products, it is common to either assume that the carbon impacts of forestry are neutral (i.e. no net emissions) or to credit harvested wood products as a carbon store. When comparing virgin and recycled materials, this means that forest carbon flows are either shown as nil or a net sequestration credit. However, harvested wood products typically account for less than half of the carbon stored in a forest, with additional stores in below ground biomass, deadwood, litter and soils. Each of these stores may be affected by changes in demand for virgin pulp and paper. %26lt;br%26gt;In this study the countries likely to provide pulp displaced by moving to recyclate, or used when switching from recyclate were identified for both the UK and China (the largest export market for UK-derived recyclate). Changes in forest carbon stores in each country were then assessed and attributed to the extraction of a unit of timber in each country where demand for pulp and paper was identified as a driver for change. %26lt;br%26gt;The analysis shows that when switching from virgin to recycled content within the UK and China, no additional biogenic CO2 emissions are avoided with the exception of Canadian pulp, where the data suggests that forests are being degraded, with associated carbon losses. %26lt;br%26gt;When switching from recycled to virgin content, net biogenic CO2 emissions are seen from most relevant countries. In the example of newsprint, this is equivalent to 2-23 tonnes CO2 per tonne of newsprint. The exceptions to this are Chile and Russia, where demand for virgin fibre does not appear to be associated with deforestation. Despite limitations, the research highlights that biogenic carbon is a significant issue which may dominate the outcome of LCAs assessing the climate change impact of switching between virgin and recycled pulp.
- 出版日期2012-10
