When it makes Black smoke, why to call it as green?

 Greenhouse gases & Global warming

• 30% of the portion of energy is reflected or scattered back to the space 
• Stratosphere absorbs about 19% of the available energy (like UV) is absorbed by the clouds, gases (like ozone), and dust.
• About the 51% of the sun’s radiation reaches the surface of the earth, and this can heat the surface to an average temperature of -20°C.

If this is the case, water will remain as ICE all over the earth. There will be no water in liquid or in gaseous form, as a result Earth will appear as white Ball.

Greenhouse Effect

    Solar radiation is absorbed by the surface and re-emitted back to the atmosphere as longer wavelength. Absorption of longer wave radiation causes additional heat energy to the atmosphere. Over 90% of energy is directed back to the earth surface, and again this process is repeated, until no longer wave is available for absorption.

  And this process contributes the heating up of earth to an average temperature of +15° C

    That is why we have green vegetation on the earth and we call these black smokes as greenhouse gasses.

What if the amount of Greenhouse Gas increases?

  The amount of heat energy added to the atmosphere is controlled by the concentration of greenhouse gases. 

  For example: Venus's surface absorbs about 2.5% of incident solar. It has atmosphere consisting of more than 96% carbon dioxide. Venus has by far the hottest surface of any planet in the Solar System, with surface temperature of 737 K (464 °C).

Conclusion:

   All of the major greenhouse gases have increased in concentration since the beginning of industrial revolution (about 1700 AD). Addition of greenhouse gases to the atmosphere will enhance the heating up of earth, and results in warmer Earth climate. Such a effect is called Global warming.

  Increase of Greenhouse gases concentration by the anthropogenic activity results in Global warming.

Reference: 

Atmosphere, Ocean, and Climate Dynamics - An Introductory Text (John Marshall & R. Alan Plumb).

Climatology – second edition – (John E Oliver, John J Hidore) 

Atmospheric Thermodynamics - John M. Wallace, Peter V. Hobbs.