Here we use satellite observations to quantify several key biophysical properties across latitudinal tree line for a series of sites throughout the pan-boreal region We find decreases in NDVI and increases in albedo across the transition from boreal forest to tundra, as expected. However, in the absence of topographical barriers we find that these transitions can occur over upwards of 100 km, and that biophysical properties characteristic of tundra ecosystems can occur as far as 100 km south of tree line. Albedo is compared to NDVI and several satellite derived proxies for tree density (e.g. Vegetation Continuous Fields) in order to test for the existence of a sharp gradient that may constitute of biophysical tree line. Our results indicate that the biophysical characteristics of latitudinal vegetation gradients are poorly characterized by traditional tree line representations. Consequently, it is likely that land surface models overestimate surface radiation budgets and carbon fluxes in the boreal biome. When satellite observations of albedo are compared to GCM's from the AR5 model archive we find large differences between modeled and observed albedo under both snow covered and snow-free conditions. Model errors are generally not systematic, varying between models, and regionally within models. These results suggest that land surface characterizations are likely to cause errors in modeled energy budgets for the Arctic, with potential implications for regional climate feedbacks. This will be particularly important for modeling the climate feed back effects associated with vegetation change in the Arctic.