Global climate change

Since climate change started to be recognized as a major environmental challenge, there has been increasing concern about its impacts on society. These impacts include higher average global temperatures as well as increasing risks for weather extremes and rising sea levels that can inundate low-lying coastal areas and islands.

According to the 2007 report from the Intergovernmental Panel on Climate Change (IPCC), the warming of the global climate is now unequivocal. The IPCC also concludes that the warmth of the last half century is unusual in a time perspective of 1,300 years. The rate of change appears to be increasing and eleven of the twelve years between 1995 and 2006 were the warmest since the beginning of instrumental records. The consequences of this global warming are becoming increasingly apparent, with observational evidence from all continents and most oceans that many natural systems are affected by regional climate change. Many observations are from the Arctic. One of many signs of climate change is that sea ice has shrunk by almost 3 percent per decade since the beginning of the satellite data records in 1978. At a global level, observations have now documented more intense and longer droughts since the 1970s, especially in the tropics and subtropics, increased frequency of heavy precipitation, and widespread changes in weather extremes, such as heat waves.8

By now it is well established that the most important factor behind the warming of the climate system is an increase in anthropogenic greenhouse gases. In its 2007 report, the IPCC concludes with "very high confidence that the globally averaged net effect of human activities since 1750 has been one of warming."9 The most important of the

8 IPCC, Climate Change 2007: The Physical Science Basis. Summary for Policymakers; IPCC, Climate Change 2007: Climate Change Impacts, Adaptation and Vulnerability. Summary for Policymakers. Working Group II Contribution to the Intergovernmental Panel on Climate Change Fourth Assessment Report (Gevena: Intergovernmental Panel on Climate Change, 2007).

9 IPCC, Climate Change 2007: The Physical Science Basis. Summary for Policymakers, 3.

greenhouse gases from human activities is carbon dioxide. Today, the atmospheric concentration of this gas is higher than it has been in the past 650,000 years. Adding to this disturbing observation is that the growth rate in carbon dioxide was faster during the past decade (1995-2005) than it has been since measurements began. This indicates that the political recognition of climate change as a major challenge to human society has not yet led to any change in the trend of constantly increasing global emissions. The major source of carbon dioxide is the burning of fossil fuels with a lesser contribution from land-use changes, such as deforestation.

Climate change has often been viewed as a global issue and today this framing is firmly entrenched in structures of climate governance as intergovernmental in nature and global in scope. However, the global view has also been challenged from many directions. Politically it has been questioned because it hides the fact that the industrialized global North is responsible for the lion's share of the historical emissions of greenhouse gases.10 Efforts to deal with climate change are now also occurring in other international fora based on an idea that many paths can lead to the same goal.11 There are also growing numbers of sub-national initiatives.12 Analytically, social scientists have started to actively seek new vantage points in order to better understand global-local interactions in knowledge production and policy.13 Within international assessments of climate science, there is increasing attention to the fact that climate change and its impacts will vary across the world and subsequently a drive towards focusing more on impacts and vulnerability at the regional level. This includes the development of climate models with higher resolution to make the scenarios more useful for national or local planners and policy makers who have to make decisions about adaptation to climate change. In short, the challenge of climate change is no longer only a global matter.

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