In early February 2007 and the Intergovernmental Panel on Climate Change (IPCC) released a report on scientific explanations, observations and projected impacts of climate change the world. The report also describes the extent of human contribution to climate change that. The following article is intended to provide a brief description about the message of the report. To facilitate delivery, this paper presented in the form of questions and answers.
What is the meaning of climate?
Climate is the average and variation in temperature, evaporation, precipitation and wind over a certain period in the range in a matter of months until millions of years.
What is the difference between weather and climate?
Briefly climate can be regarded as the average of the weather. The difference, predicted weather for a period of more than a few days is very difficult because of its relatively high uncertainty. In contrast, estimates of climate change caused by changes in atmospheric composition or other factors, in general, the relative can be done.
What affects the earth's climate?
In the earth's climate is strongly influenced by the heat balance on earth. The flow of heat in the Earth's climate system works because of the radiation. The main source of radiation on Earth is the sun.
Can you explain how the mechanism of thermal equilibrium it?
Of all the solar radiation leading to the surface of the earth, a third reflected back into space by the atmosphere and the Earth's surface (see Figure 1). Reflection by the atmosphere due to clouds and particles called aerosols. The presence of snow, ice and desert plays a crucial role in reflecting back the sun's radiation that reaches the earth's surface.
Two-thirds of the radiation that is not reflected, the amount of about 240 Watt/m2, absorbed by the earth's surface and atmosphere. To maintain thermal equilibrium, the earth radiates back to the heat absorbed in the form of short-wave radiation. Some short-wave radiation emitted by Earth is absorbed by certain gases in the atmosphere are called greenhouse gases. Furthermore, the greenhouse gases radiate heat back to earth. This mechanism is called the greenhouse effect. The greenhouse effect is what causes the earth's temperature is relatively warm with an average of 14oC, without the greenhouse effect the earth's temperature is only about-19oC.
A small percentage of heat that is on earth, called latent heat, is used to evaporate water. This latent heat is released again when water vapor condenses in clouds (see Figure 1).
Figure 1: The thermal equilibrium in the Earth System
What is included in the group of greenhouse gases?
Greenhouse gases is the most dominant water vapor (H2O), followed by carbon dioxide (CO2). Another greenhouse gas is methane (CH4), dinitro-oxide (N2O), ozone (O3) and other gases in smaller quantities.
Is the so-called global warming?
Global warming is the increase in average temperature of the atmosphere near the surface of the earth and the sea over the past decade and projections for some time to come.
Is global warming really is happening?
Observations during the past 157 years show that Earth's surface temperature increased by 0.05 oC / decade. Over the last 25 years getting a sharp increase in temperature, amounting to 0.18 oC / decade (see Figure 2). Symptoms can also be seen from meingkatnya warming ocean temperatures, rising sea levels, melting ice and decreasing snow in the northern hemisphere.
Figure 2: Increase in average temperature of the earth for 157 years
How global warming could happen?
Global warming occurs due to the enhanced greenhouse effect which disebebakan by rising concentrations of greenhouse gases in the atmosphere. The higher the concentration of greenhouse gases, the more heat radiation from Earth is trapped in the atmosphere and radiated back to earth. This causes an increase in surface temperature of the earth. Increased temperatures due to climate could also increase the sun's radiation, but the effect is relatively very small.
What causes the increase in greenhouse gases?
Human activities is believed to be because of increased concentrations of greenhouse gases.
How does the human role in influencing the increased concentration of greenhouse gases?
Human activities, primarily the burning of fossil fuels and agricultural activities, resulting in emission of greenhouse gases are CO2, CH4, N2O and halokarbon (group florine gas containing chlorine and bromine). These gases are accumulating in the atmosphere that cause an increase in concentration over time. This increase is very noticeable in the industrial era as shown in the following figure.
Figure 3: Concentrations of some greenhouse gases during the last 2000 years.
How big is the human contribution to global warming when compared to natural factors other?
Warming or global cooling is influenced by natural factors and human factors. Which includes natural factors is the level of solar radiation and volcanic eruptions. Rise and fall of solar radiation affect the earth's temperature fluctuations. Meanwhile, volcanic eruptions penuruanan effect the earth's temperature for a few moments. Human activities also give effect to the rise and fall of temperature of the earth. However, if accumulated, then the whole of human activity on Earth's temperature increases far greater than the contribution of other factors. The contribution to global warming is termed radiative forcing. The greater radiative forcing greater contribution to global pemasan (see picture below).
Figure 4: Components of radiative forcing from human and natural (solar radiation).
Does the increase of water vapor in the atmosphere due to global warming will increase the greenhouse effect?
Yes. This is called positive feedback effect (positive feedback effect).
Is there another positive feedback effect?
There, the melting of ice and snow due to global warming. With the melting of ice and snow, land surface that were previously closed to open. Because the soil is darker than snow and ice, the more heat is absorbed by the earth's surface, which in turn increases the temperature of the earth.
Are extreme climate phenomena of late related to global warming?
Many statistics are menunujukkan so. The incidence of extreme climatic phenomena over the last century showed an increase. Among these extreme events include the long dry season in Australia (2003), the high temperatures during summer in Europe (2003), duration of hurricane season in North America (2004 and 2005), heavy rainfall in India (2005), etc. . In contrast, the number of extreme events such as extremely cold nights has decreased.
Could global warming is only caused by natural variation?
It is unlikely that global warming is only caused by natural variation. Climate models that only take into account natural variations (especially solar and volcanic activity) without considering the effect of greenhouse gases that failed to produce an output in accordance with reality / observations. The simulation results to be accurate after entering the effects of greenhouse gases into the model. This is as shown in the following figure.
Figure 5: Climate models with and without including human factors
Did the events of extreme climate will change along with climate change the world?
The answer, yes. Heat waves estimated to be more intensive, more frequent and last longer. In areas with four seasons, the number of days with temperatures lower than the freezing temperature will be minor. The summer will be drier and winters will become more humid. In addition, the intensity of tropical storms will be higher.
If greenhouse gas emissions be reduced, how quickly the concentration of gases in the atmosphere will be reduced?
The answer depends on the type of gas. Concentrations of some of the gas would immediately be reduced immediately by a reduction in emissions, but some of them even remain elevated for several centuries after such reduction (see figure below).
Figure 6: Penuruanan concentrations of greenhouse gases after the introduction of emission reduction (a) CO2, (b) of greenhouse gases by 120-year life cycle, and (c) of greenhouse gases by 12-year life cycle
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