Food Harvest 2020 is a national plan for intensification of agriculture with specific targets to be delivered by 2020. The plan envisages increases in output across a range of farm enterprises – dairying, beef, sheep and pigs. The motivation for this study was to examine the environmental sustainability of the Food Harvest 2020 targets. The study was carried out on the River Boyne catchment area. A wide-ranging environmental systems analysis was carried out to assess the environmental impacts associated with the intensification of agricultural production envisaged in Food Harvest 2020. The following environmental impacts were assessed using Life Cycle Assessment (LCA) modelling: Global Warming Potential, Primary Energy Use, Eutrophication Potential, Acidification Potential, Abiotic Resource, Pesticide Use and Land Use. Ideally, one would aim for a full LCA approach for all commodities in the agricultural sector. However, this was not possible because of the complexity. The scope of the study was therefore limited to 10 arable crops and 4 livestock production systems. Following an extensive review of the literature and consultation with expert opinion, the Cranfield LCA Systems Model was selected to carry out the analysis. This model proved to be very suitable as it was specifically developed for agricultural purposes. The modelling identified significant increases in environmental burdens associated with intensification of milk production, beef production and pig production. There are a number of strategies that could mitigate or offset to some degree the increased environmental burdens. The recommendation from this study is that the implementation of Food Harvest 2020 should be tied to a package of transparent and verifiable mitigation measures. Some of the mitigation measures may be cost neutral and others may not. In any case business as usual is not a sustainable scenario.