How would a low-carbon energy transformation affect energy security? This paper proposes a framework to evaluate energy security under long-term energy scenarios generated by integrated assessment models. Energy security is defined as low vulnerability of vital energy systems, delineated along geographic and sectoral boundaries. The proposed framework considers vulnerability as a combination of risks associated with inter-regional energy trade and resilience reflected in energy intensity and diversity of energy sources and technologies. We apply this framework to 43 scenarios generated by the MESSAGE model as part of the Global Energy Assessment, including one-baseline scenario and 42 'low-carbon' scenarios where the global mean temperature increase is limited to 2 degrees C over the pre-industrial level. By and large, low-carbon scenarios are associated with lower energy trade and higher diversity of energy options, especially in the transport sector. A few risks do emerge under low-carbon scenarios in the latter half of the century. They include potentially high trade in natural gas and hydrogen and low diversity of electricity sources. Trade is typically lower in scenarios which emphasize demand-side policies as well as non-tradable energy sources (nuclear and renewables) while diversity is higher in scenarios which limit the penetration of intermittent renewables. (C) 2013 Elsevier Ltd. All rights reserved.