The Science of Global Warming

Abstract

Global warming is unequivocal, as is manifested in three internationally known global temperature records with the global average temperature rising at a rate of 0.70–0.75◦C per 100 years during 1910–2009 [Wen et al., 2011]. In other words, the earth has warmed more than 0.8◦C since the Industrial Revolution. If it is true that 2◦C above pre-industrial level is a threshold of climate “safety”, we will have to confront a serious situation where less than 1.2◦C warming is permissible in the future [Liu et al., 2011]. According to climate system concept [Wang, 2011], the global warming is not only reflected in global temperature change but also in changes of other climate system components, such as widespread melting of snow and ice, rising of global average sea level, and permafrost degradation [IPCC, 2007]. Due to its great influences and potential risks on the society, global warming now attains more and more concerns from governments, scientists and public media. Today, global warming becomes one of the most important issues, which must be taken into consideration in strategic decision making of national development. As a scientific issue, however, global warming has been studied for almost 200 years [Mitchell, 2002; Cullen, 2011]. And it now has evolved as an independent discipline closely associated with meteorology, oceanography and environmental sciences. In order to review the development of global warming concisely, in this paper, we shall only focus on the science of global warming itself, excluding impacts, adaptation and policy associated with global warming. In 2011, Archer and Pierrehumbert [2011] compiled the previous studies on the global warming and added their brief comments. This work offered a great foundation for further investigating global warming. In order to understand global warming systematically and comprehensively, we summarize ten essential issues based on the five cornerstone literatures from Archer’s compilation together with four IPCC Assessment Reports and the First World Climate Conference. These ten issues will be reviewed as follows. Greenhouse effect Joseph Fourier was the first scientist argued for the greenhouse effect in 1824 [Archer and Pierrehumbert, 2011]. The earth receives energy from the sun and re-radiates to outer space. Calculations based on the planetary energy balance indicate that the temperature of the earth is much lower than 0◦C as opposed to the observation of 14◦C. This discrepancy is believed to be produced by the atmosphere, which traps more long-wave radiation from earth surface and keeps the earth warmer. A mechanism named greenhouse effect is proposed to describe this process. Greenhouse gases An Irish scientist Tyndall in 1849 verified through his designed experiments that CO2 has greenhouse effect on earth’s climate [Tyndall, 1861]. He was the first to correctly measure the relative infrared absorptive powers of the gases including