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Understanding the Environmental Impact of Wool (IWTO)

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This paper is part of a Wool Science project, launched by the Sustainable Practises Working Group and is written by Ona Viljoen, and based on a recent study by SG Wiedemann, MF Yan BK Henry and CM Murphy – August 2016. A comprehensive new study, which provides much more information regarding the environmental impact of Australian wool than any previous study, was released recently. This is also the first study to investigate greenhouse gas emissions in three different production regions with three different types of Merino sheep.

The study, Resource Use and Greenhouse Gas Emissions From Three Wool Production Regions of Australia by S.G. Wiedemann, M.J. Yan, B.K. Henry and C.M. Murphy, was published in the Journal of Cleaner Production (S.G. Wiedemann et 132 al. / Journal of Cleaner Production 122 (2016) 121-132) and was made available online on 17 February 2016.

The wool textile industry has over the years seen a number of Life Cycle Assessment (LCA) reports, but to date only two detailed LCA studies have been published for Australian wool, reporting only the single impact of greenhouse gas emissions (GHG) from a single case study farm. This resulted in a knowledge gap regarding the environmental performance of wool.

The new study is making a valuable contribution to previous research and is the first multiple-impact LCA on resource use and GHG emissions for different production regions in Australia. It also uses a much broader farm dataset.

This study was undertaken in response to increased demand from garment manufacturers, retailers and general consumers for information regarding the environmental impact of fibre products. However, the authors emphasize that determining the environmental impact of wool production is much more complex than for man-made fibres because, compared to wool, the latter have relatively consistent and regulated systems for the raw material phase of the supply chain.

The impact of wool on the environment, on the other hand, differs considerably from region to region because production intensity varies, the level of inputs differs, while the climate also differs from one region to the next.

According to the authors, wool’s environmental credentials have to date been modelled on inventory data that may not accurately reflect Australian production practices and performance data. Land use (LU) and direct land use (dLU) for cradle to farm gate production have not been included in previous studies.

This study also presents the first wool specific analysis of water use with comprehensive LCA methods.

The study investigates the impacts from three major wool productions regions with three specific aims:

To quantify resource use (energy, water and land occupation);
To estimate greenhouse gas emissions, including those associated with land use (LU) and direct land use change (dLUC) from wool production; and
To identify impact hotspots in the production system.
The system boundary included all supply chain processes associated with the primary production of wool up to the farm-gate.

Farms from geo-spatially defined production regions in three broadly defined Australian agro-climatic zones were selected. These regions were located in the western wheat-sheep zone of West Australia producing fine Merino wool, the eastern high-rainfall zone of New South Wales producing super-fine Merino wool, and the southern pastoral zone located in central South Australia producing medium Merino wool.

Farms in the western wheat-sheep region produce wheat and other grains on arable land, and typically grazed sheep on non-arable land, or land being used for pasture leys within the cropping cycle. Grazing is supported by native pastures with introduced clover. Supplementary feeding and forage crops are used to manage annual feed deficiencies in summer. Wool is produced from large-bodied Merino sheep, producing fine wool (20 µm) and lambs for meat production.

Farms in the eastern high rainfall region in New South Wales are typically mixed grazing enterprises, producing wool, lamb and beef with only small areas of cropland used for forage. Grazing is supported by native pastures with introduced clover, or sown pastures. Wool is typically produced from smaller bodied Merino sheep, producing super-fine wool (17 µm) and smaller lambs for meat production.

The southern pastoral region of central South Australia contains large sections of arid desert lands, with smaller areas of semi-arid native grasslands or savannas, which support low densities of sheep and cattle, with no cropping and few alternative farming systems available. Wool is produced from large-bodied Merino sheep, producing medium micron wool (21-22 µm) and lambs for meat production.

Data were collected from 10 case study farms (CSF’s) via site visits, interviews and a survey of each farm in 2013-14. A further 34 farms were included for the specialist sheep farm dataset, covering five years from 2006 to 2010 (ABARES 2013) to account for inter-annual variation as a result of seasonal variation.

An analysis of regional average farms (RAFs) was performed using farm survey data collected from specialist sheep farms as part of the Australian Agricultural and Grazing Industries Survey performed annually by the Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES).

According to the authors the CSF dataset provided highly detailed data regarding flock management and biophysical resources such as land and water, albeit for a limited number of farms in each region and for one or two years only. “The RAF dataset provided a larger number of farms in each region, and repeated measures over a longer time frame (five years), but contained less detail regarding some biophysical resources and flock management,” they stated.

Modelling of energy demand was based on the inventory of purchased goods, services and transport distances. Capital infrastructure (buildings, fences) and machinery were excluded based on their minor contribution (<1% of impacts) assessed during the scoping phase.

Livestock GHG emissionswere determined by applying methods outlined in the Australian NGGI (Commonwealth of Australia 2015) where specific tier-two methods were available, or from the IPCC (De Klein at al., 2006).

The authors explain that fresh water consumption refers to evaporative losses, or uses that incorporate water into a product that is subsequently not released back into the same river catchment. “The focus on fresh water consumption reflects the intent of LCA to investigate the impacts of resource use, either on human health, natural ecosystems or competitive water users.”

None of the farms used in the study used irrigation water for pasture production. However, water use was dominated by supply losses and to a lesser extent direct drinking water requirements.

The study found that water resource use was highest in production regions with low annual rainfall where the reliance on water from small farm dams was high and evaporation losses were also high. Applying the appropriate water stress index (WSI) showed wool to have a relatively low impact on constrained water resources in the three regions.The WSI indicates the portion of fresh water consumption that deprives other users of fresh water, and is thus a measure of scarcity of fresh water.

An important finding was that stress weighted water use results showed much lower values than fresh water consumption.


The study concluded that the “impact of using water to produce wool in these Australian regions is comparatively low both in terms of competitive water uses (i.e. for human consumption or industry) or the environment.”

The study also found that fossil energy demand varied significantly in response to climate, production intensity and level of inputs. Arable land occupation and energy demand was highest in the mixed grazing and cropping regions where larger amounts of supplementary feed grown on arable land was used for sheep production.

The highest energy values were observed in Western Australia where fertiliser and pesticide inputs associated with pasture and forage were much higher. In the extensive management systems used in the pastoral zone in central South Australia, fertiliser use was lower, resulting in lower energy demand.

It was clear from the study that non-arable land comprised the largest proportion of total land occupation, which indicated low resource use for crop land that can be used for other fibre and food production systems.

The results showed that GHG emissions (excluding LU and dLUC) did not significantly differ between regions or wool type. Emissions ranged from between 19,5 ±4,1 kg CO2 equivalent to 25,1±4,8kg CO2

equivalent. Methane was the largest contributor (79-89%) followed by nitrous oxide (9-11%), mainly from animal manure, and CO2 (3-9%).However, a regression analysis of individual farms in the CSF dataset revealed a trend towards higher impacts from systems where wool yield per sheep was lower (i.e. New South Wales high rainfall zone case study farms). Differences in wool and meat production per ewe were largely associated with the type of Merino sheep bred in each region.

The study found that different methods for handling co-production of greasy wool and live weight (for meat production) changed estimated total GHG emissions by a factor of three, highlighting the sensitivity to this methodological choice and the significance of meat production in the wool supply chain. It also highlights the importance of production efficiency as a means to reduce emissions.

The authors concluded that further research was required using consequential analysis methods to more accurately determine the environmental impacts from a change in wool production.


The study is available, open access, from the journal website:

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