Human pressures increasingly threaten the highly biodiverse freshwater ecosystems. Life Cycle Analysis (LCA) is a useful tool to reveal the impacts of products and services on freshwater biodiversity. Current methodologies in LCA address the impact of climate change driven by reduced average river discharge on freshwater biodiversity. However, given the ectothermic nature of fish, previous studies have highlighted the importance of including water temperature changes as a driver of species loss. In addition, the impact of climate-driven changes in extremes might be more important than changes in average conditions. This thesis develops a novel methodology to include the impacts of climate change on freshwater biodiversity in LCA. A novel dataset of range contractions, based on extreme streamflow and water temperature parameters, is converted into extinction risk via a metric originating from the classic Species Area Relationship (SAR). A characterization factor is derived for each of the 63 greenhouse gases (GHGs) included in the study. The recommended sets of global characterization factors range from 1.33·10-15 - 7.16·10-11 PDF·yr·kg-1 for the average approach and 4.62·10-16 - 2.49·10-11 PDF·yr·kg-1 for the average and marginal approach respectively. The results imply that freshwater biodiversity impacts per unit of GHG have been underestimated in previous LCA methods that excluded the impact of extreme values and water temperature-driven losses. Future contributions can help to increase taxonomic coverage (e.g., by including lentic species and macro-invertebrates) and by developing complementary models to reflects all the various levels of biodiversity.