This briefing note outlines the scientific conditions under which warming can be limited to well below 2°C over the 21st century, and return to below 1.5°C by 2100. It provides a scientific overview of the science on some critical mitigation technologies, like bioenergy, carbon capture and storage, and their combination – BECCS. It also contains counter arguments to claims that 1.5°C scenarios undermine food security through including large scale bioenergy deployment. The considerations in this briefing are based on the findings of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5), the 2014 UNEP Emissions Gap Report, the Report of the UNFCCC Structured Expert Dialogue (SED), as well as the recent scientific literature.