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15/04/14 09:30

Increase in size of greenhouse gas sink

An official statistics publication for Scotland.

Between 2011 and 2012 the amount of greenhouse gases removed from Scotland’s atmosphere due to Land Use, Land Use Change and Forestry (LULUCF) increased by three per cent.

Scotland’s Chief Statistician today announced the release of the latest estimates of emissions and removals of greenhouse gases from LULUCF. The figures show that Scotland’s LULUCF activities are a net remover, or 'sink', of greenhouse gases in the atmosphere. This means that overall these activities result in more greenhouse gases being removed from the atmosphere than released. The size of the Scottish sink has increased by more than five-fold between 1990 and 2012. In 2012, LULUCF net emissions were -5.7 million tonnes of carbon dioxide equivalent (Mt CO2e).

Of the land types examined in the report, forest land removes the greatest amount of greenhouse gases from the atmosphere, the sink increasing by over 30 per cent between 1990 and 2005. Over the last 40 years the rate of afforestation has decreased. Combined with conifer plantations established in the mid-20th century reaching their planned rotation age now being felled and replanted, this has resulted in the size of this annual sink remaining relatively constant. Wood products produced as a result of these felling operations have resulted in an increase in the sink reported by the harvested wood products category.

The report also examines the emissions and removals from cropland, grassland, wetlands and settlements. Of these, cropland is the largest producer of greenhouse gases in Scotland, though emissions have reduced by 30 per cent since 1999.

While most of the emissions and removals relate to carbon dioxide, in 2012 there were over 300,000 tonnes CO2e of nitrous oxide emissions and nearly 30,000 tonnes CO2e of methane emissions.

The report was produced by the Centre for Ecology and Hydrology for UK government departments.

Notes to editors

The LULUCF sector includes carbon stock changes, emissions of greenhouse gases (CO2, methane and nitrous oxide) by sources and removals of CO2 by sinks (primarily forestry). Removals of greenhouse gases are conventionally presented as negative quantities.

The full statistical publication “Emissions and Removals of Greenhouse Gases from Land Use, Land Use Change and Forestry (LULUCF) for England, Scotland, Wales and Northern Ireland: 1990-2012” is available at: http://naei.defra.gov.uk/reports/reports?report_id=788

Greenhouse gas emissions and removals are reviewed every year, and the whole historical data series is revised to incorporate methodological improvements and new data. Changes to UK LULUCF emissions were first reported in February when 2012 UK Greenhouse Gas Emissions, final figures were published - https://www.gov.uk/government/publications/final-uk-emissions-estimates

There are large differences in the estimated net emissions compared with the 2011 inventory published in April 2013, due to changes in methodology. The most significant change in methodology was a change in the model used for carbon accounting in the forestry sector and a subsequent change in the forestry activity data fed into the models. Previous inventories were based upon the C-Flow model which uses representative broadleaf (beech) and conifer (sitka spruce) species to model all forests in the UK with constant management regimes and harvesting times. The new inventory was compiled using the CARBINE model which is able to represent all of the introduced and native tree species relevant to the UK, the different growth rates of forests and four broad classes of forest management (clear-fell with thinning, clear-fell without thinning, thinned but not clear-felled and no timber production). The revised method gives a more realistic representation of UK forestry.

As part of the move to the CARBINE model, the forestry datasets which provide input to the model have been changed. Planting data have been back-dated to 1500, whereas with C-Flow, all forests planted prior to 1920 were assumed to be in carbon equilibrium. Deforestation rates have also increased from those used in previous submissions which were believed to under-report deforestation. The data on harvested wood products produced by CARBINE is more closely related to timber production statistics rather than the standard rotation lengths assumed by C-Flow.

There are also some small changes due to the inclusion of new activity data, including 2011 data for agricultural liming and peat extraction which were published too late to be captured in the 2011 report. Further methodological information can be found in the report.

As a result of these changes, while the 2011 inventory reported the size of the LULUCF sector sink increasing by 3.2 Mt CO2e between 1990 and 2011, the 2012 inventory shows the sink increasing by 4.7 Mt CO2e over the same period. Net emissions from the LULUCF sector in 2011 were reported as -5.3 Mt CO2e in the 2011 inventory compared with -5.5 Mt CO2e in the 2012 inventory.

Historical statistics for net Scottish greenhouse gas emissions from all sources will be updated when the full greenhouse gas emissions statistics for 1990, 1995, 1998-2012 become available in June 2014.

Further information on Environment statistics within Scotland can be accessed at: http://www.Scotland.gov.uk/envstats

Official statistics are produced by professionally independent statistical staff – more information on the standards of official statistics in Scotland can be accessed at: http://www.scotland.gov.uk/Topics/Statistics/About