Early environmental assessments of emerging products and technologies are essential for their responsible integration in the global economy. However, at a pre-commercial stage, the data are often inadequate. This introduces epistemic uncertainty (i.e., that due to lack of information), which is more qualitative in nature, and addressing it is important for the applicability of the assessment. Additionally, the science communication literature indicates that a transparent presentation of uncertainty is important for a correct interpretation and credibility of the results. Given the high level of epistemic uncertainty in pre-commercial assessments, it is all the more important that this uncertainty not only is addressed systematically, but that its communication is made tangible to the experts and non-experts alike, especially when the topic is of public interest.

Under three distinct but related themes, this dissertation presents the frameworks for reducing and communicating various aspects of epistemic uncertainty in the life cycle assessments (LCAs) of emerging technologies as follows. (1) The uncertainty due to the immaturity of technology and differences in production scale is addressed under Theme I. The two LCAs under this theme indicate that the higher levels of technology maturity and production scale are likely to reduce environmental impacts. However, the magnitude of this reduction would depend on the aspects such as the reuse-recyclability potential of the input material and the current level of technology maturity. Additionally, it appears that this reduction may not be apparent in the assessments of the laboratory level processes if there is higher uncertainty in the technology's path to commercialization. (2) Theme II introduces a theoretical framework for fusing heterogeneous and possibly conflicting information, in order to enhance the data quality, which in turn can reduce the epistemic uncertainty. (3) Theme III addresses the communication of uncertainty in general. Existing Peer-reviewed LCAs of engineered nanomaterials provide the case study material for this theme. This study identifies the critical elements of uncertainty communication, which in itself is an essential component of effective science communication. It also proposes certain graphical presentations to effectively convey the uncertainty, mainly the epistemic uncertainty, in the LCAs of emerging technologies. I believe that assimilation of these three frameworks in the methodology of LCAs would serve in enhancing the applicability, and therefore the decision informing capacity, of the assessments.