Including CO_2-emission equivalence of changes in land surface albedo in life cycle assessment. Methodology and case study on greenhouse agriculture

摘要

Purpose Climate change impacts in life cycle assessment (LCA) are usually assessed as the emissions of greenhouse gases expressed with the global warming potential (GWP). However, changes in surface albedo caused by land use change can also contribute to change the Earth's energy budget. In this paper we present a methodology for including in LCA the climatic impacts of land surface albedo changes, measured as CO_2-eq. emissions or emission offsets. Methods A review of studies calculating radiative forcings and CO_2-equivalence of changes in surface albedo is carried out. A methodology is proposed, and some methodological issues arising from its application are discussed. The methodology is applied in a practical example dealing with greenhouse agriculture in Southern Spain.rnResults The results of the case study show that the increase in surface albedo due to the reflective plastic cover of greenhouses involves an important CO_2-eq. emission offset, which reduces the net GWP-100 of tomato production from 303 to 168 kg CO_2-eq. per ton tomato when a 50-year service time is considered for the agricultural activity. This example shows that albedo effects can be very important in a product system when land use plays an important role, and substantial changes in surface albedo are involved. Conclusions Although the method presented in this work can be improved concerning the calculation of radiative forcing, it constitutes a first operative approach which can be used to develop regionalized characterization factors and provide a more complete evaluation of impacts on the climate change impact category.