Research Example 3: The Evolution of the Atmosphere of the Earth

Who researched:
Michael H. Hart
Where researched:
Laboratory for Planetary Atmosphere, NASA/Goddard Space Flight Center
Greenbelt, Maryland
When researched:
Received February 21, 1977
Revised June 20, 1977
Research methods used:
-Calculated/researched changes in the solar luminosity, variations in the Earth’s albedo, the greenhouse effect, variation in the biomass, and a variety of geochemical processes
-Assumed/approximated: degassing, condensation of water vapor, photodissociation/escape of hydrogen, oxidation of surface minerals, presence of life, limits on the biomass, urey reaction, photosynthesis and the burial of organic sediments, chemical reactions/solubility of gases, changes in solar luminosity, albedo and greenhouse effect
-Based on calculations, research, assumptions and approximations, Hart was able to run several computer simulations that measured:
levels of N2, O2, CO2, CH4, NH3, AR and H2O (grams)
surface pressure (atm)
effective temperature/surface temperature (degrees Kelvin)
What he found:
-CO2 levels significantly decreased but are on the rise again
-N2 has significantly increased
-CH4 and other reduced carbon compounds have decreased and are on the rise again
-O2 has increased
-Atmospheric pressure has gone up and down but is currently on its way back up
-Surface temperature has decreased but effective temperature has increased
-Water vapor has decreased significantly
-Argon has been on a steady rise since the beginning of Earth
-Cloud cover has significantly decreased but has been slowly rising again recently
-Albedo decreased, plateaued and has started to slowly rise again
-Organic carbon in sedimentary rocks has steadily increased
-Extra O2 in rocks has steadily increased
-Mass of CO2 in limestone has been on a steady increase since the beginning of Earth, however recently it has started to decline
What this means/Why it’s important:
The evolution of the Earth’s atmosphere can teach us several things. First, it can help us predict what the Earth’s atmosphere will be like in the future. This could potentially help us adapt to our environment faster than the slow process of evolution. Second, knowing what our atmosphere was like in the past can help us explain past natural phenomena and past biomass/biodiversity. And lastly, the ability to compare our atmosphere now with the atmosphere of the past can clue us into how we have affected our environment.