Global environmental issues are those that transcend national borders, such as transboundary migration of contaminants or so-called invasive species via atmospheric or aquatic pathways, or issues that are universal or common to many countries. They are particularly important because of the spatial magnitude of their impact, but are often the most difficult to manage because of the multiple jurisdictions involved. Scientific input is crucial to inform governments and public opinion and minimize longer term impacts. Multinational scientific bodies can play an important role in facilitating scientific discussion. With its membership distributed over 78 countries in 4 geographic regions, the Society of Environmental Toxicology and Chemistry (SETAC) is poised to be a key forum for bringing together academic and industry scientists, environmentalists, and politicians to examine and resolve these complex challenges.
The most pressing global issue today is climate change. Suspicion, alarm, skepticism, doubt, debate, denial, possibility, evidence and, lastly, almost certainty, describe the evolution of both public and expert reactions to the scientific discourse surrounding this topic over the past nearly 2 decades. Now there is heightened pressure for action. The latest stage in this evolution occurred in Paris, France, in February when Working Group I of the Intergovernmental Panel on Climate Change (IPCC) adopted the Summary for Policymakers as part of the 1st volume of ''Climate Change 2007'', also known as the Fourth Assessment Report (AR4; IPCC 2007). The AR4 is intended to update previous IPCC reports on climate change prepared in 1990, 1995, and 2001 with new information on the current scientific knowledge of the natural and human drivers of climate change, observed changes in climate, the ability of science to attribute changes to different causes, and projections for future changes. This latest report on the state-of-science, a disturbingly grim summary document, concludes that global warming is ''very likely'' caused by mankind and that climate change will continue for centuries even if heat-trapping gases are reduced.
Climate change is inexorably linked with energy use and greenhouse gas emissions. The environmental impacts of global warming are far reaching, from coral bleaching in tropical areas to melting of the polar icecaps. There can be major impacts on water availability in some regions of the world, at the same time other regions are challenged by sealevel rise and flooding in coastal and low-lying areas. The balance of natural ecosystems is threatened, in the oceans through changes in CO 2 absorption and pH, and loss of habitat for key terrestrial species. The subtleties of many of these effects on ecosystem structure and function have yet to be fully understood. Environmental scientists are already taking on the challenges of assessing, understanding, and providing recommendations on how mankind should react to these potential environmental changes.
According to the nearly 800 contributing authors from 130 countries who contributed to the IPCC summary report, the science is so well documented that the time has now come for