Global Warming : Dr. Mahbub Khan,USA

There has been a series of heat waves all across USA during the last week (July) including the greater Los Angeles area in California where the temperature exceeded 120-degF causing health alarms in some areas. So, we were discussing about this very hot days amongst a few of our BUFLA-Friends through text messages, and an action item came out of this discussion for me to write a short article on the sciences of “Global Warming” so that everybody can understand. So, here is the short writing on it, and I am going to keep it very simple so that everyone can understand. A couple of weeks ago I did a short posting to you on “Summer-Solstice” which has some relevance to this current high temperature, and I hope you had a chance to read it. I have included that short article here again below for your second reading at the end of this writing on Global-Warming.

I will very briefly mention the sciences of what is global warming, why that happens, how that happens, what are the impacts of it on the planet Earth and on its residents and what we can do to avoid this wrong path. The very first basic thing that we must understand first is “Light” which is a member of the family of Electromagnetic waves. Here is a diagram of the family members of the Electromagnetic wave family: (Radio wave, Microwave, Infrared, Visible-Light, Ultraviolet, X-ray and Gamma-ray).

All of these 7 different types of waves are exactly the same except the lengths of the waves (wavelength) as you can see in the picture above. These waves are called the Electromagnetic waves because the Electric field and Magnetic field oscillate perpendicular to each other while the wave itself moves forward, perpendicular to both E-and-M fields, with the highest possible speed in the universe as 186,000 miles per second. So, the wavelength is very important to note here. The shorter the wave, the higher is the energy, and that is why the short wavelength X-rays kill the body cells, UV gives skin cancer, but visible light of longer wavelength is ok and we are safe in even longer wavelength radio waves and we can listen to radio-music safely.

Next item to understand is that everything radiates. All objects at all temperatures radiate at various wavelengths, including the human bodies, grounds, ocean-water, trees, buildings, furniture and everything around you, except an object at absolute zero (K) in Kelvin scale. This is called black-body radiation as shown in the picture below where the peak of the wavelength distribution shifts to the left (towards shorter wavelength) as the temperature of the object rises.


Now that you know the significance of wavelength and the phenomena of black-body radiation that everything radiates at various wavelengths, let us now go to the Home Depot store at their nursery department with glass roof and glass walls where the plants of fruits, vegetables and flowers are stored. The first question is why the nursery dept has the glass walls and glass ceilings while the main building is made up of brick-and-concrete walls and concrete ceilings? Here is the answer: Glass allows the visible light wavelength (400 nm to 700 nm) from the sun to go in through it but the glass does not allow the Infrared longer wavelength light from the plants and grounds to go out through the glass. So, energy is coming in but it cannot get out. So, the interior of the nursery warms up that the growing plants need. This is called Greenhouse effect. Object achieved.

Now let us go to our next important item, which is the air that we breathe (atmosphere). The atmosphere consists of about 80% Nitrogen and about 20% Oxygen. Our heart pumps in impure blood from the body and pumps it out to the lungs and as we breathe in air into the lungs, oxygen interacts there to purify the blood and we breathe out CO2. The heart then pumps in the pure blood from the lungs and pumps out the clean blood to the body. Those are the 4 compartments of the heart in use. So, heart is a pump with 4 pockets, and no pump, no life. Anyway, the plants then take our breathed out CO2 for their photosynthesis and gives out Oxygen for us as shown in the picture below.



So, plants are our good friends and we should smile at them every morning and be nice to them.

Next important item to understand is the radiations of various wavelengths that is coming from the sun and which wavelengths are reaching out all the way to the surface of the Earth. This is shown in the picture below, which shows that only the visible wavelength and Radio wavelengths are reaching the surface of the Earth and other wavelengths are stopped (absorbed) by various layers of our atmosphere. Thank God the atmosphere is stopping those bad radiation, because otherwise we could be getting all cancers and diseases and deaths.


Next important item to realize is that our atmosphere has some Greenhouse gases which are as follows: Water Vapor, Carbon dioxide (CO2) Methane (CH4) and Ozone (O3). Clouds also affect the radiation balance. This naturally occuring Greenhouse gases cause air temperature near the surface of the Earth to be warmer by about 33-deg-C (59-deg-F). So, without the Greenhouse gases of the Earth’s atmosphere, the Earth’s average temperature would be well below the freezing temperature of water. In that case life could not be possible on Earth without liquid water. Thank God we have some Greenhouse gases in our atmosphere to stay alive and not frozen to death.

So, we are almost coming to the final point. Just like the glass walls of the Home Depot nursery, our atmosphere allows the visible wavelength of light from the sun to come to the surface of the Earth but the Greenhouse gases in the atmosphere do not allow the Infrared radiation from the Earth to go into outer space. So, the energy is trapped and the Earth warms up like the nursery. There is an amazing balance of naturally occurring Greenhouse gases in the atmosphere which stops just the right amount of infrared radiation to maintain the comfortable level of temperature on Earth. Too little of the Greenhouse gases will make the Earth colder and too much of it will make the Earth warmer which is what we are doing by our bad practices. The diagram below shows the effect of the Greenhouse effect cycle:



Human activity since the Industrial revolution by using bad chemicals and fossil fuel burning (as shown in the picture above) has increased the amount of Greenhouse gases in the atmosphere including the Carbon dioxide, Methane, tropospheric-Ozone, CFC (Chloro-Fluro-Carbon) and Nitrous Oxide. This is causing the increased Greenhouse gases that is warming up the planet Earth. The 3rd chart above shows the Carbon dioxide emission in the atmosphere by various countries. Given below are 2 diagrams of temperature changes during the past centuries and its recent effects.



The effect of increased Greenhouse gas include the increased global temperatures, rising sea levels, inundation of coastal cities, changing precipitation and rains, expansion of deserts in the subtropics, melting of ice and glaciers, extreme weather, heat waves, droughts, heavy rainfall with floods, heavy snowfall, ocean acidification, species extinction and human food security.

There are various attempts to control the emission of Greenhouse gases into the atmosphere. Many countries of the world are parties of the United Nations Framework Convention on Climate Change (UNFCCC). The ultimate objective of this Convention is to prevent dangerous human interference on the global climate system, including the Greenhouse gas emission issue. There were world headline news recently on the “The Paris Agreement on Climate Change” and whole world has criticized the negative role of USA in this very important matter. Hopefully the world population as a united body will remain committed to keep the environment safe, clean, healthy and well for us and for our future generations for centuries and centuries to come and beyond.


Effect of Global Warming

For additional information please visit the following link, which I have used for some of the information:


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