Climate Change 2
1. Diagnosis and Forecast of Global Climate Change
1.1. Present Conditions of Global Warming
Climate refers to the long-term variation in the atmospheric conditions
of a specific region or regions, and thus climate change means a gradual change in the climate system, both by natural and artificial causes. Climate change is caused by changes in each component of the climate system such as the atmosphere, hydrosphere, biosphere, cryosphere and lithosphere and/or by complicate interactions among those components. The causes of climate change are largely divided into natural causes and artificial causes. Natural causes are attributed to changes caused by variations in solar activity, changes in sea water temperature, ice cap distribution, westerly waves and atmospheric waves as well as the incidence of volcanic eruptions. On the other hand, artificial causes include carbon dioxide emission from the production activities of industry and agriculture, deforestation, acid rain and the destruction of the ozone layer by Freon gas, with global warming being caused by the increase of greenhouse gases, with carbon dioxide being representative of a greenhouse gas (Presidential Advisory Council on Education, Science ＆ Technology: PACEST, 2007).
Global warming refers to the average increase of the Earth’s temperature due to the greenhouse effect caused by carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbon (HFCs), perfluorocarbon (PFCs) and sulfur hexafluoride (SF6).2 Global warming, meaning a continuous increase of the Earth’s temperature due to the greenhouse effect, started from the Industrial Revolution, as the Industrial Revolution brought about a rapid increase in fossil fuel consumption.
Global warming has attracted growing international interest as the scientific knowledge of climate has gradually accumulated since the
2 The Greenhouse effect refers to a phenomenon where atmospheric elements such as water vapor and carbon dioxide prevent the solar energy that has reached the Earth from being radiated back into space, resulting in a rise in the average tem-perature of the Earth’s atmosphere. This idea was first proposed by a Swedish chemist, Svante Arrhenius, in 1896 in a study in which he postulated that the in-creasing the carbon dioxide concentration in the atmosphere might result in a temperature rise (E. S. Shin and H. S. Kim, 2005. p.103).
1970s and it has now been widely accepted by the scientific community that anthropogenic greenhouse gas emissions are the primary cause of global warming.
Global greenhouse gas concentrations, based on carbon dioxide, are estimated to have increased from 280ppm before the Industrial Revolution (1750) to 379ppm in 2005. According to the analysis of average temperature of the Earth (Climate Research Unit, 2006), the increase in the Earth’s average temperature since the Industrial Revolution appears to have been much higher than the increase prior to the Industrial Revolution. Moreover, global warming has significantly accelerated since 1980; the average temperature in 1998 was shown to be 0.58℃ higher than the average temperature of 1960 ~ 1990 <Figure 2-1>. As shown in the figure, 11 of the 12 hottest years since 1850 were recorded as occurring in the last 12 years.
In order to achieve a systematic and reliable diagnosis of global warming, scientific analyses of climate change have been periodically collated by the IPCC since 1990. Thus far, the IPCC has published its
Figure 2-1. Temperature deviation from the average temperature of 1961~1990
Temp. Deviation
1860 1880 1900 1920 1940 1960 1980 2000 년 (℃ )
0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6
Source: Climate Research Unit (2006)
First (1990), Second (1995) and Third (2001) Assessment Report and its Fourth Assessment Report is being prepared given that Working Group I (Physical Science of Climate Change), Working Group II (Impacts, Adaptation, Vulnerability) and Working Group III (Mitigation of Climate Change) announced their reports in April 2007 (IPCC, 2007).3
The IPPC WGI Report, which is based on physical science, suggests that with regards to global warming the carbon dioxide concentration has increased about 1.4 times (to 379ppm in 2005) over the past 100 years when compared to the pre-industrialization concentration (280ppm). Accordingly, it is estimated that the average global temperature has risen 0.74℃ (0.56∼0.92℃) over the past 100 years (1906~2005) <Figure 2-2>. Additionally, the estimates show that the average temperature of the Northern hemisphere in the late 20th century appears to be the highest in the temperature records since 1850 and that the temperature rise over the last 20 years is shown to be more than twice that of the past 100 years. This report states that there is no doubt that global warming is occurring in the climate system and affirms that greenhouse gas emissions is an artificial cause of global warming.4
3 The Intergovernmental Panel on Climate Change (IPCC) is an international organ-ization founded in 1988. Its 4th Assessment Report, published in April 2007, in-volved 2,500 scientists around the world over a 6 year period. 130 countries ac-knowledged the validity of the Report (Presidential Advisory Council on Education, Science ＆ Technology, 2007).
4 The IPCC 3rd Assessment Report (2001) estimates that the average global temper-ature has risen by 0.6℃ over the past 100 years and that this may have been due to artificial causes. However, the 4th Assessment Report uses more assertive expressions.
Figure 2-2. Average global temperature and change trend
Annual Temp. Deviation Estimated Average GlobalTemperature ( °C)
1860 1880 1900 1920 1940 1960 1980 2000 14.6 14.4 14.2 14.0 13.8 13.6 13.4 13.2 0.6
0.4 0.2 0.0 -0.2 -0.4 -0.6 -0.8
As global warming continues, the temperatures at the North Pole and the South Pole have risen, accelerating the rate at which the ice cap is melting, shortening the ice-breaking period in the polar lakes and thus leading to a significant rise in the sea level. Furthermore, global warming causes extreme climatic phenomena such as more severe floods, droughts and heat waves, thereby increasing the occurrence of natural disasters worldwide (Korea Meteorological Administration: KMA, 2008b).5
1.2. Current Conditions and Forecasts of Global Climate Change
Global climate change is affected by various factors such as regional characteristics, socioeconomic variables and meteorological variables.
The IPCC Assessment Report provides a number of greenhouse gas
5 A few example of natural disasters caused by global warming include a flood in China in 1995, the inundation of the Rhine in 1997, a flood in eastern Europe in 2000, a flood in Mozambique and in Europe in 2000, and a flood in Bangladesh in 2004.
emission scenarios. Different assumptions, related to demographics and socioeconomic development, are used in each scenario and thus each scenario arrives at a different future greenhouse gas concentration. The Special Report on Emission Scenario (SRES) presents four main scenarios (A1, A2, B1, B2) and three other scenarios (A1F, A1T, A1B) which are modified according to technological variable employed in the A1 scenario <Figure 2-3>.
The A1 scenario assumes very-rapid economic growth, in which the rapid growth of global economy and population peaks in 2050 and declines thereafter. It also assumes that new, more efficient technologies are introduced. The A1 scenario is split into three, each of which makes different assumptions on the future development of energy technology.
The three scenarios are the fossil intensive scenario (A1F1), the non- ossil energy scenario (A1T), and a balanced-energy source scenario (A1B)
Figure 2-3. Conceptual diagram of scenarios for estimating climate change
Emphasis on Economic Growth
Harmony between Environment and Economy
Localization Globalization
A1 World of Very Rapid Economic Growth (A1F, A1T, A1B)
A2
Heterogeneous World
B1 World of Continuous Development
B2
World where Regions Coexist
The A2 scenario assumes a heterogeneous world with a high population growth rate, a low economic growth rate, and the most diversified, but slowly developing, technologies.
The B1 scenario assumes the same population growth rate as that of the A1 scenario but with a lower economic growth rate. In this scenario, the economic structure changes toward a service and information economy and sustainable development is pursued with an emphasis on clean and resource-efficient technologies.
The B2 scenario assumes a world where regions coexist with each other in harmony. This scenario assumes an intermediate level of population and economic growth, between A1 and B1, and focuses on regional solutions for economic, social and environmental sustainability.
The average global temperature by the end of the 21st century (2090~2099) is estimated to rise by 1.1 ~ 6.4℃ compared to the period from 1980~1999, with a rise in sea level by 18~59cm due to heat expansion and the loss of land glaciers <Table 2-1>.
Estimates of future climate change vary greatly from scenario to scenario. In the continuous development scenario (B1), in which the environmental conservation and the economic development are compatible
Table 2-1. Estimated temperature rise for 2100 in each scenario
Scenario Temperature Change (℃) Sea Level Rise
Optimal Estimation Expected Range (cm) Very rapid economic growth
(A1FI) 4.0 2.4 ~ 6.4 26 ~ 59
Non-fossil intensive energy
(A1T) 2.4 1.4 ~ 3.8 20 ~ 45
Balanced-energy source (A1B) 2.8 1.7 ~ 4.4 21 ~ 48
Heterogeneous world (A2) 3.4 2.0 ~ 5.4 23 ~ 51
Continuous development (B1) 1.8 1.1 ~ 2.9 18 ~ 38
Coexistence of regions (B2) 2.4 1.4 ~ 3.8 20 ~ 43
Source: IPCC (2007), p.8.
with each other, the temperature change is estimated to be about 1.8℃
(1.1~2.9℃), while a rise of about 4.0℃ (2.4~6.4℃) is expected in the very rapid economic growth scenario (A1) with its emphasis on fossil- intensive energy sources. By 2030, however, it is estimated in all scenarios that temperature will rise at a rate of 0.2℃ for every ten years
<Figure 2-4>.
According to the IPCC Fourth Assessment Report, the impact of global warming will greatly vary according to the degree of temperature rise and the latitudinal location. When the temperature rise is less than 1℃, damage due to natural disasters such as water shortages and floods are predicted in some areas. However, the report warns that if the temperature rises by 2~3℃, most areas will be subject to damage due to natural disasters and the future survival of about 20~
30 percent of animals and plant species will be endangered. Furthermore, if the temperature rises by more than 3℃, significant economic and environmental damages are to be expected, including aggravated water shortages, ecosystem destruction, reduced food production, and the increased occurrence of diseases.
Figure 2-4. Estimated trend of temperature rise in each scenario
A2A1B
B1Year 2000 Constant Concertration 20th century
1900 2000 2100
Year 6.0
5.0 4.0 3.0 2.0 1.0 0.0 -1.0
Source: IPCC (2007).
Though global warming has negative impacts in general, it is also suggested that it may have some positive impacts to a certain extent.
One of the positive impacts is that the higher carbon dioxide concentrations serves to increase photosynthesis, in much the same way as fertilizer application results in the increase in crop growth or quantity. This positive impact is called the “CO2 fertilization effect.” It was once reported that if CO2 concentration increased by 200ppm from the present concentration, there would be an increase of about 10~ 15%
in the quantity of agricultural crops, such as wheat and soybeans harvested (Ueji, Seino, and Minami. 2005).