Solar energy radiation
Without sun energy, earth would be a very cold place, about -243C almost the same as average universe temperature -270C. Since the solar emits just enough energy to earth, or about 1368 W/m2 (also known as solar constant), which is then absorbed by the surface of the earth about 168W/m2, and the cloud about 67W/m2, the earth surface will maintain its warm temperature about 15C to make the life on earth possible.
But, what about the other side of the earth which is not directly get the solar radiation?, or we can say “night” part of the earth. Theoretically, the temperature will be -18C, the water will be freezing, and it is not an ideal place to life.
Greenhouse gases
Fortunately, our earth covered with the blanket of gases known as greenhouse gases. These gases absorb 90% the radiation emitted by the earth surface, let say about 390W/m2 at 15C, hence about 350 W/m2 absorbed. And this keeps the earth surface temperature warm even at night.
The effect of warming underneath ground from the trapped heat reflected back is analogously with the effect occurs in the green house for gardening. So, we call it the greenhouse gases.
The composition of natural greenhouse gases are O2 (55%), CO2 (39%), CH4 (2%), N2O (2%), O3 (2%), and halocarbons.
Global Warming
The right amount of green house gasses on the atmosphere makes the temperature of the earth just right. But, if the gases increasing, it will make the surface temperature of the earth increase. Maybe in average it is just 1-2C, but this slight change in temperature could affect dramatically for the human life. The ice in the pole can be melt, then rise the sea water level, which can cause a floods in some countries.
The natural event such as mount eruption could make this change. But, mostly this increase is due to a human activities, and the emission is also called the anthropogenic green house gas.
These are the following anthropogenic gas emission due to the activities energy (84%), agriculture (8%), industrial processes (5.5%), waste (2.5%). the data was measured in 2003. With the proportions of CO2 (74.4%), CH4 (16.7%), NO2 (6.4%), Other (2.2%) measured in 2010.
The water vapor actually have a huge contribution to the greenhouse gasses proportion (55%), but the cycle is very fast, following the water cycle. The bad news is, some gases such as CO2 will remain in the atmosphere for more than a century. Unfortunately, our source of energy is fossil fuel, which emits mostly CO2 gas.
This is why most of the countries are pursuing a new “clean” source of energies, or make some transition in the consumption of their energy. And this is also become the major issue in we must concern, because of the almost irreversible effects caused by it.
By: Caesar Wiratama
source: Christian Ngo, Joseph B. Natowitz. Our energy future: resources, alternatives, and the environment. Second edition. John Wiley & soons, inc. 2016
