Climate Change [Ctd.]
What are the greenhouse gases and their contribution to the climate change?
Generally, water vapor, carbon dioxide (CO2), CFC, methane (CH4), and also nitrous oxide (N2O) contribute to the greenhouse effect and therefore, are known as greenhouse gases.
Most dominant contributor
Water vapor is the most dominant greenhouse gas. However, the concentration of water vapor is largely determined by the atmospheric temperature. Higher temperatures promote the evaporation of water and consequently increase the concentration of water vapor in the atmosphere which in turn intensifies the global warming.
This implies that the largest contributor to the climate change, water vapor is not a root cause of global warming but a product of global warming caused by other greenhouse gases. Can you imagine?
It is a vicious cycle!
So… What is the most deleterious greenhouse gas?
Let’s take a look at the following pie chart to find out the correct answer. It illustrates the contribution of individual greenhouse gases to the greenhouse effect (Without considering the effect of water vapor). We can see that carbon dioxide alone accounts for 55% of the warming effect.
Figure 1: Contribution of greenhouse gases to the greenhouse effect 
Since water vapor is a result of global warming, the second largest contributor to the climate change, carbon dioxide is considered to be the most deleterious greenhouse gas.
This implies we must lower the concentration of carbon dioxide in the atmosphere in order to mitigate the climate change successfully.
How to start
To begin with, let’s see…what are the anthropogenic sources of greenhouse gases?
Greenhouse gases are produced in various human activities where power plants, vehicles, cement plants, mining plants and industries are the most dominant sources. Just take a look at the following pie chart. It shows the annual greenhouse gas emissions, in 2005, by sector. It can be seen that the electricity generation and heating make up nearly a quarter of the total greenhouse gas emissions while transportation sector accounts for 14.3% of the emissions. Further, it can be perceived that the combustion of fuels (electricity, heating, transportation, etc.) as a whole accounts for nearly 50% of the total amount of greenhouse gas emissions.
Figure 2: Annual world greenhouse gas emissions, in 2005, by sector
As we can see, fuels (crude oil, coal and natural gas) are the largest sources of greenhouse gases (especially CO2, N2O and SO2) and key contributors to the climate change. So, it is obvious that our fight against the climate change requires to minimize our fuel consumption. Efficient use of energy and energy efficient appliances are proven ways to minimize the energy demand. However, rapidly increasing demand for energy requires more and more energy and thus more fuels.
Keep in mind: Even a significantly improved modern coal-fired power plant with a capacity of 1000 MW pumps six million tons of emissions into the atmosphere annually! 
We need to minimize the fossil fuel consumption. But we need more and more fossil fuels to fulfil the ever-increasing demand for energy since fossil fuels are our primary source of energy.
We are really on the horns of a dilemma!
How to deal with this impasse?
The short answer is searching for alternatives to the fossil fuels: renewable energy sources.
In next article, let’s focus on renewable energy sources and their importance in climate change mitigation.