As noted in the previous chapter, climate change has emerged in recent years as one of the most critical topics at almost all levels of decision making, both private and public. This constitutes a radical change compared to the common perception only a few years ago. Climate change, a result of global warming, is a reality of universal acceptance, affecting in many ways the life of human societies as well as the environment. Continuing research over the last decades has established concrete knowledge of the basic facts about the results of interactive processes in the Earth system,which determine climate and climate change. It has particularly shown the anthropogenic influences on these processes. There is no doubt that human activities are the critical cause of the changes in the climate that Earth is experiencing since the Industrial Revolution in the mid-18th century, i.e. since the time that a period of rapid industrial growth with far reaching social and economic consequences begun in Britain and spread to Europe and other countries all over the world. The industrial revolution marked the beginning of a dramatic increase in the use of fossil fuels, which is the main cause of climate change.
TopIntroduction
As noted in the previous chapter, climate change has emerged in recent years as one of the most critical topics at almost all levels of decision making, both private and public. This constitutes a radical change compared to the common perception only a few years ago. Climate change, a result of global warming, is a reality of universal acceptance, affecting in many ways the life of human societies as well as the environment. Continuing research over the last decades has established concrete knowledge of the basic facts about the results of interactive processes in the Earth system,which determine climate and climate change. It has particularly shown the anthropogenic influences on these processes. There is no doubt that human activities are the critical cause of the changes in the climate that Earth is experiencing since the Industrial Revolution in the mid-18th century, i.e. since the time that a period of rapid industrial growth with far reaching social and economic consequences begun in Britain and spread to Europe and other countries all over the world. The industrial revolution marked the beginning of a dramatic increase in the use of fossil fuels, which is the main cause of climate change.
This chapter, which aims to introduce the basic facts of global warming, is almost exclusively based on the latest UN’s Intergovernmental Panel on Climate Change (IPCC) Report (IPCC, 2007), particularly on Working Group I’s Fourth Assessment Report on the Physical Science Basis of Climate Change (IPCC, 2007a), agreed in February 2007, called the “Report” in the sequel of this chapter. Although the Report, despite its grave conclusions about the future of the Earth’s climate, has been criticized as a rather optimistic treatment of the subject, it has gained widespread acceptance as it is supported by the most recent and reliable scientific evidence available. Indeed, the Report has been based on concrete scientific findings characterized by a certainty equal or greater than 90%, while ignoring less certain but more pessimistic scenarios. The Report, however, has been amended in the IPCC’s synthesis report published in November 2007, which highlights the risk of very large (negative) impacts of the global warming effect on the Earth’s climate.
The Report is a detailed account of the latest scientific findings on climate change, and more specifically on the changes, due to global warming, in atmospheric constituents and in radiative forcing (the term is defined in the sequel). It summarizes observations regarding surface and atmospheric climate change, changes in snow, ice and frozen ground and oceanic climate change and sea level. While starting with a historical overview of Climate Change Science, it also covers subjects such as Palaeoclimate, couplings between changes in the Climate System and Biogeochemistry, climate models and their evaluation and global and regional climate projections. Understanding and attributing climate change is also treated in the Report. Additionally, the Report provides a Summary for Policymakers, a Technical Summary and an “Uncertainty Guidance Note”. Several annexes are also included, such as glossary, authors and reviewers annexes.
A fundamental contention of the Report is that the cause of climate change is human activities after the Industrial Revolution. The Report points out that, since the IPCC First Assessment Report in 1990, and as climate science and the Earth’s climate have continued to evolve over recent decades, increasing evidence of anthropogenic influences on climate change has been found. Correspondingly, the IPCC has made increasingly more definitive statements in its successive reports about human impacts on climate. Debate has stimulated a wide variety of climate change research. The results of this research have refined but not significantly redirected the main scientific conclusions from the sequence of IPCC assessments.
While the above will be analytically presented in this chapter, in order to introduce the subject, a schematic framework representing anthropogenic drivers, impacts of, and responses to climate change, and their linkages is given in Figure 1 (IPCC, 2007, p. 26).
Figure 1. Schematic framework of anthropogenic climate change drivers, impacts and responses. (Source: IPCC, 2007)