legislation has emerged, which now extends to all areas of environmental protection, including: air pollution control, water protection, waste management, nature conservation, and the control of chemicals, biotechnology and other industrial risks. The Institute for European Environmental Policy estimates the body of EU environmental law amounts to well over 500 Directives, Regulations and Decisions. Environmental policy has thus become a core area of European politics. Such dynamic developments are surprising in light of the legal and institutional conditions which existed in the late 1950s and 60s. Acting without any legislative authority, European policy-makers initially increased the EU's capacity to act by defining environmental policy as a trade problem. The most important reason for the introduction of a common environmental policy was the fear that trade barriers and competitive distortions in the Common Market could emerge due to the different environmental standards. However, in the course of time, EU environmental policy emerged as a formal policy area, with its own procedures. The legal basis of EU environmental policy was not more explicitly established until the introduction of the Single European Act in 1987. Initially, EU environmental policy was rather introspective. More recently, however, the Union has considered global environmental governance. The role of the EU in securing the ratification and entry into force of the Kyoto Protocol in the face of US opposition is an example in this regard. This international dimension is reflected in the EU's Sixth Environmental Action Programme, which recognises that its strategic objectives can only be achieved if a series of key international environmental agreements are actively supported and properly implemented both at an EU level and worldwide. The entry into force of the Lisbon Treaty further strengthens the EU's global environmental leadership ambitions. The vast body of EU environmental law which now exists has played a vital role in improving habitat and species protection in Europe as well as contributed to improvements in air and water quality and waste management. However, significant challenges remain, both to meet existing EU targets and aspirations and to agree new targets and actions that will further improve the environment and the quality of life in Europe and beyond. One of the top priorities of EU environmental policy is combating climate change. In 2007, member states agreed that the EU is to use 20% renewable energy in the future and that it has to reduce carbon dioxide emissions in 2020 by