The four environmental impact categories being targeted are:
• Climate change potential: is an increase in temperature caused by the emission of greenhouse gases into the atmosphere. The target is a 17% reduction
• Eutrophication potential: is the amount of nutrients such as nitrate and phosphate from manure or slurry that ends up in the aquatic environment. The target reduction is 15%
• Acidification potential: relates to the release of acidic gases such as ammonia, again from slurry or manure or sulphur dioxide from burning fossil fuels. These have the potential to form acid rain which, in turn, can damage ecosystems The target is a 15% cut
• Abiotic resource depletion potential: estimates the use of scarce natural resources including fossil fuels. The target here is a reduction of 16% achieved through even greater efficiencies.
http://www.bpex.org.uk/articles/301332/BPEX_Environment_Roadmap_Launched__27_April_2011.aspx