The environment, energy and climate are transboundary issues that require cooperative action to sustainably address. To meet our energy requirements, both the UK and Europe are heavily reliant on energy imports. As international concerns rise over the impacts of climate change and over increasing levels of geopolitical unrest, UK Government energy policy must balance the need for competitive energy prices, with the requirements to ensure security of supply and to achieve environmental sustainability. Much of the UK’s environmental policy and legislation derives from EU Directives. Some sectors of industry may argue that this imposes a burden on their business, whilst others may argue that it leads to stability of Government policies and that it enables long-term decision-making and investment. Environmental groups do contend that European Directives provide a much-needed safety net, to protect the environment over timescales longer than a UK electoral cycle. This safety net is particularly effective because the successful implementation of EU Directives must be evidenced, protecting the progress of these policies, particularly during periods of financial stress.As part of a larger grouping of countries, negotiations on the world stage (such as climate negotiations) can be conducted with more authority than would be possible as an individual country, since the countries represented by the EU collectively represent a larger proportion of the global population, and account for a larger proportion of consumption and emissions. Cross-European R&D projects have a wider geographical scope, cover a broader range of environments and draw upon a larger pool of skills and researchers than would be possible if projects were centred within a single country. Such projects are facilitated by a number of EU mechanisms– though it is possible that non-EU countries can gain access to EU research activities, e.g. through associate country status.The implications for energy, environment and climate, of a move to leave the European Union are not clear. It is clear, however, that environmental policy in the UK has historically been driven by European legislation, that the UK is deeply embedded within the European energy market, and that the UK (and European) economies are heavily reliant on energy imports. Whatever the UK decides, it is critical that improved energy security remains a Government priority, and that we adopt a move towards a fully integrated energy, environmental and climate policy