The challenge of building consensus beyond the scientific community.

• Author: Wirth, Timothy E.
• Position: Environmental protection

The imminence and severity of problems posed by the accelerating changes in the global climate are becoming increasingly evident. Heatwaves are increasing in severity, droughts and downpours are becoming more intense, the Greenland ice sheet is shrinking, sea levels are rising and the increasing acidification of the oceans is threatening to disrupt the marine food chain.

The window of opportunity for keeping atmospheric concentrations of greenhouse gases within an acceptable range is closing, while the costs of mitigation and adaptation are rising relentlessly. At the same time, there is also an increasing convergence of science, economics, technology and finance to guide joint international action to address climate change. A sustainable energy future is clearly both possible and affordable, but increased political will and greater collaboration between developed and developing countries are required. These steps must be built on a foundation of public understanding and support.

Scientists worldwide have spoken conclusively. The Intergovernmental Panel on Climate Change (IPCC), jointly established by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), is one of the most sweeping and successful scientific collaborations in history. Its fourth assessment of climate change science could not be any clearer: human activities are altering the atmosphere, and the planet is warming. Unless we act now, with a great sense of urgency, there is significant risk that the Earth's environmental systems will cross a tipping point, beyond which costly and disruptive impacts all over the world will be inevitable.

According to IPCC, if current emission patterns are not altered, global temperatures are expected to rise an additional 1.8° to 4° Celsius. Such warming would prove extremely harmful, if not catastrophic, for our environment, economy and society, and would disproportionately affect the world's poor, whose livelihoods are most closely tied to agriculture and other natural resources.

Climate change is certainly the greatest environmental challenge facing humanity and may also be the greatest economic and political challenge. Forging global consensus on cooperative strategies for mitigating and adapting to climate change is a formidable challenge. But the world's scientific community has spoken unambiguously. If we fail to act with urgency and forthrightness, global climate change will have dangerous...