5 June 2007 Greenhouse gas emissions from human activities are causing our world to get warmer. Concentrations of carbon dioxide in the atmosphere are higher than at any time for the past 600,000 years, and the rate of increase is accelerating. The most dramatic evidence of climate change is found in the Polar Regions. The Arctic is warming twice as fast as the global average. The extent and thickness of permanent Arctic sea ice is diminishing; areas of permafrost, frozen for centuries, are thawing; and ice caps in Greenland and the Antarctic are melting faster than anyone anticipated. For the people and ecosystems of the Arctic, the implications are profound. Retreating sea ice is reducing habitat for vulnerable Arctic species. The changes will also affect Arctic indigenous communities who depend on the natural world, not just for food, but for their cultural identity. However, this is not just a polar issue. The theme for World Environment Day 2007 -- “Melting Ice: A Hot Topic!” -- reflects the impact that climate change is having in all regions. As sea levels rise, inhabitants of low-lying islands and coastal cities throughout the world face inundation. The world’s insurance companies are paying out more and more each year to compensate for extreme weather events. As glaciers retreat, governments are casting an increasingly anxious eye at future water supplies. And for the one-third of the world’s population living in drylands, especially those in Africa, changing weather patterns linked to climate change threaten to exacerbate desertification, drought and food insecurity. Society’s dependence on fossil fuels is jeopardizing social and economic progress and our future security. Fortunately, there are many policy and technological options available to avert the impending crisis, but we need increased political will to use them. Developed countries in particular can do more to reduce greenhouse gas emissions and encourage energy efficiency. They can also support clean development in fast-growing economies such as Brazil, China and India, as well as adaptation measures in those countries that face the greatest hardships from climate change. On this World Environment Day, let us recognize the need to slow the momentum of the dramatic environmental changes we are seeing at the poles and around the globe. And let each of us pledge to do our part to fight climate change.