LIST OF EQUATIONS
2. Chapter 2 Impact of Climate Change on Pavement Resilience Resilience
2.2. Climate Change
2.2.1. Theory on Climate Change
17
2. Chapter 2 Impact of Climate Change on Pavement
18
On the other hand, paleoclimatologists have concluded, after examining the isotopes of gases (oxygen or hydrogen), that the past climate change is shaped in the form of a linear relation between the isotopic composition and temperature (Petit et al. 1999). Moreover, tree rings can also be used to assess past climate condition (Petit et al. 1999). By studying climate variation such as precipitation and sunlight, paleoclimatologists can define accurate dating for tree growth. Moreover, ice ages, which resulted in extreme cold periods on the planet, are pure evidence of the natural variations in the climate. This has been seen through glaciers that covered large areas of the Earth. Today, the ice age has ended and glaciers have melted and retreated (Petit et al. 1999; Wolff 2005; Qiao 2015).
Scientists have developed a historical climate reading based on the ice core record to understand the Earth (Figure 2-1). They have defined four primary cycles that hit the Earth during ice ages over the past 400,000 years. Figure 2-1 shows the association between atmospheric carbon dioxide concentration and the estimated historical temperature. Nowadays we are in an increasing mode (too high temperature peaks) of heat, but it is assumed that the temperature will drop again after a certain period of time, based on temperature patterns that occurred during the past four primary ice ages. However, such a phenomenon is based on long-term trends, and temperature variations could happen in the short term (Petit et al. 1999, Qiao 2015).
Figure 2-1: Atmospheric carbon dioxide concentration and estimated historical temperature (Petit et al. 1999)
19
Paleoclimatologists have not been able to define the reason behind the variations in the climate. However, they have established a better understanding of some significant factors such as the impact of the orbit of the Earth on climate change (Paillard 2001). This theory was first introduced by James Croll in the 1860s. In 1980, Imbire established a model to define the climate reaction to the orbital parameter of the Earth based on James Croll’s theory. He used other influential factors such as changes in atmospheric compositions, variations in the solar output and change in the ocean current (Qiao 2015). As a system, the climate is on the equilibrium between heat reaching the Earth from the sun and the radiation of heat from the Earth into space. This balance is disturbed by the emission into the atmosphere of a number of gases (greenhouse gases), which will eventually lead to global climate change (Qiao, 2015). The occurrence of global climate change will impact the built infrastructure.
However, Alzahrani (2015) indicated that there are different views on climate change and the events that cause it. For example, one group of scientists and climate researchers believe that climate change stems from natural factors, whilst another group assumes that climate change was initiated before human existence by natural elements but has increased as a result of human activity. Moreover, there is another group of scientists who question the presence of climate change, stating that there are no changes in the climate and no need to invest significant funds into carrying out studies of it. Burnett (2001) also stated that it is difficult to define the size and degree of climate change, its direction and future predictions in terms of global temperature.
While a variety of theories about the term climate change have been suggested, this research will use the theory first suggested by James Croll in the 1860s.
Qiao et al. (2015) also stated that the phenomenon of climate change is certain.Various signs in the natural forces point to the fact that the Earth has always had a changing climate (Chapman 2007), even though human activity has also contributed to this since the industrial revolution (Karl and Trenberth 2003). It is believed that human influences exaggerate climate change through inducing changes in atmospheric composition through the emission of greenhouse gases (NRC 2008).
The trend of global climate change can be seen in the form of temperature increases as a result of warmer winters, drier summers and rising sea levels, together with unusual weather patterns and a higher number of floods (IPCC 2007). The phenomena of extreme weather events and associated natural hazards can also be generated as a
20
result of climate change (Stewart and Deng 2015). The NRC (2008) has defined climate change as “a statistically significant variation in either the mean state of the climate or its variability over an extended period, typically decades or longer, that can be attributed to either natural causes or human activity weather refers to the familiar hour-by-hour, day-by-day changes in temperature, cloudiness, precipitation, and other atmospheric phenomena”. Also, the term ‘global warming’ is defined in terms of the increase in global average temperature resulting in the accumulation of greenhouse gases in the atmosphere (Wuebbles and Jain 2001).
In 1988, the Intergovernmental Panel on Climate Change (IPCC) was founded to study the problems associated with climate change and its impacts. The primary objective of the IPCC is to investigate the potential effects of climate change and advise the world community of the consequences of such phenomena. This action is conducted through continual monitoring and assessment in order to report the policy frameworks needed to address the climate change using a technical, scientific and socio-economic approach (IPCC 2013).