INTRODUCTION: THE ENVIRONMENTAL CHALLENGE
It is widely recognised that the planet faces serious environmental challenges that can only be addressed through international cooperation. Climate change and ozone depletion, loss of biodiversity, toxic and hazardous pollution of air and sea, pollution of rivers and depletion of freshwater resources are among the issues that international law is called upon to address. Since the mid 1980s, the subject of international environmental law has emerged as a discrete field of public international law, although one that is closely related to many other areas. The conditions that have contributed to the emergence of international environmental law are easily identified: environmental threats are accompanied by a recognition that ecological interdependence does not respect national boundaries and that issues once considered to be matters of national concern have international implications – at the bilateral, subregional, regional or global levels – that can often only be addressed by international cooperation, including by law and regulation.
The growing number of international environmental issues is evidenced by the large body of principles and rules of international environmental law that apply bilaterally, regionally and globally, and reflects international interdependence in a ‘globalised’ world. Progress in developing international legal control of activities has been gradual and piecemeal, and too reactive to particular incidents or the availability of new scientific evidence (such as the Chernobyl accident or the discovery of the ‘hole’ in the ozone layer). It was not until the late nineteenth century that communities and states began to recognise the transboundary consequences of activities affecting shared rivers or leading to the destruction of wildlife, such as fur seals, in areas beyond national jurisdiction. In the 1930s, the transboundary consequences of air pollution were acknowledged in the litigation leading to the award of the arbitral tribunal in the Trail Smelter case. In the 1950s, the international community legislated on international oil pollution of the oceans. By the 1970s, the regional consequences of pollution and the destruction of flora and fauna were obvious, and by the late 1980s global environmental threats had become a part of the international community's agenda as scientific evidence identified the potential consequences of ozone depletion, climate change and loss of biodiversity.