Scientists from Trinity College Dublin have found that relying on data which excludes land-use history in annual reporting on agricultural land use in Ireland has led to an underestimation of cropland emissions by 46%.
Research fellow in botany at Trinity and first author of the study, Dr Jesko Zimmerman stated that: “By looking at the 2008 to 2012 greenhouse gas commitment period set in the Kyoto protocol, we could show that relying on annual data and not including land-use history led to an underestimation of area reported as cropland by 45.7%, which in return impacts greenhouse gas accounting.”
Agriculture is one of the largest industries in Ireland. Grasslands, which are utilised by grazing animals for meat and milk production, dominate Irish farming land. As a result, Ireland is under international observation with regards to a number of environmental issues including phosphorus and nitrogen pollution, and large amounts of greenhouse gas emissions. Reporting on these issues requires precise knowledge of the area of grasslands and of other agricultural land-use. Failures in this could lead to inaccuracies in greenhouse gas accounting.
Most accounting assumes that about 90% of Irish agricultural area is being used as pasture, with a relatively small area dedicated to arable land. Accounting has also assumed that there is little change in land use over time.
Zimmerman, said that “agricultural land use in Ireland is much more dynamic than annual reports suggest.” That is to say that there may have been more land being used for crop production than recorded.
Speaking to the Irish Times, O’Brien, the EPA research fellow who took part in the study, said that the actual level of underestimation represents a small amount of carbon release from lands generally. “There are other aspects of land use that have a bigger impact on our numbers, for example draining lands, particularly draining for peat recovery. This has a much greater impact on our inventory numbers,” he said.
The research by Zimmerman was in collaboration with teaching fellow, Dr Ainhoa González; fellow emeritus, professor Mike Jones; professor of botany, Jane Stout; Phillip O’Brien of the Environmental Protection Agency (EPA); and Stuart Green of Teagasc, and was published in the journal Land Use Policy.