The Intergovernmental Panel on Climate Change (IPCC) launched the final part of its Fourth Assessment Report (AR4) on 17 November 2007 in Valencia, Spain. With over 800 contributing writers and 450 lead authors from more than 130 countries worldwide, the report, titled Climate Change 2007, is the accumulation of six years of research and provides a comprehensive assessment of the current state of knowledge on climate change.

Climate Change 2007 underlines the urgency for policymakers to act to reduce greenhouse gas (GHG) emissions. Drawing on the reports of the three IPCC Working Groups released earlier this year—The Physical Science Basis; Impacts, Adaptation and Vulnerability; and Mitigation of Climate Change—the final part, titled The Synthesis Report, stresses that “warming of the climate system is unequivocal”.  While raising serious concerns on the anticipated rise in sea-level, melting glaciers and the extinction of various species in different regions, it also offers options for mitigation and adaptation of climate change. The Report is expected to form the basis of discussions at the Climate Change Conference, to be held in Bali, Indonesia from 3 to 14 December 2007, under the auspices of the UN , where world leaders will gather to establish a road map for a post-Kyoto Protocol agreement on GHG emissions.

“I come to you humbled after seeing some of the most precious treasures of our planet threatened by humanity’s own hand”, said Secretary-General Ban Ki-moon, who arrived at the IPCC meeting from a fact-finding visit to Antarctica and South America. The first UN Secretary-General to visit Antarctica, Mr. Ban stressed: “I can tell you with assurance that global sweeping, concerted action is needed now. There is no time to waste.” Noting that the world’s scientists had cited clear evidence of climate change, he added that “the breakthrough needed in Bali is an agreement to launch negotiations for a comprehensive climate change deal that all nations can embrace”. Calling for political solutions from Governments, he looked forward to seeing countries, such as the United States and China, play “a more constructive role” in the negotiations in Bali.

Aerial view of melting glaciers in Antarctica UN photo Eskinder Debebe

Carbon dioxide (CO₂) is the most important anthropogenic GHG, says the Report, stating that the annual CO₂ concentration levels have risen dramatically between 1995-2005. Indicating that climate change may bring “abrupt and irreversible” global impacts, it also highlights the challenges that humankind would be facing in the future:

• In Africa by 2020: It is anticipated that between 75 million and 250 million people will face increased water shortages.
• In Asia by 2050: Coastal areas, especially in the heavily-populated delta regions, will be at great risk for sea flooding; the region will also face a decrease of freshwater availability.
• Small Island States: Sea-level rise is expected to exacerbate flooding, storm surge, erosion and other coastal hazards.

The Report points out that “neither adaptation nor mitigation alone can avoid all climate change impacts. However, they can complement each other and together can significantly reduce the risks of climate change.”
“We need a new ethic by which every human being realizes the importance of the challenge we are facing and starts to take action through changes in lifestyle and attitude”, noted Rajendra Pachauri, Chairman of the IPCC. Governments had a wide variety of policies and instruments available to create incentives to mitigation, especially in the area of carbon emissions, he said.

Noting that the Report is also a “citizen’s guide” that leads people to engage in issues relating to climate change, Achim Steiner, Executive Director of the United Nations Environment Programme (UNEP), said that “unless people care about what’s written in this Report, political leaders cannot move. It is only citizens who ultimately will bring the political will to bear upon the negotiations”. Michel Jarruad, Secretary-General of the World Meteorological Organization (WMO), called for a more detailed and continuing observation of the impact of climate change which, he explained, would help individuals, businesses and civil society make more informed decisions about how to best implement adaptation and mitigation strategies.