Before Charles Keeling measured CO2, what did scientists think about the CO2 level in the atmosphere?What would the CO2 concentration be in 2100 if we do nothing?Why is the site of Mauna Loa chosen for taking greenhouse gas measurements?Besides CO2, what other measurements do scientists take at the observatory? 5. Please write down the following information for five anthropogenic greenhouse gases:5.1. Name and chemical formula5.2. Lifetime range5.3. Global Warming Potential (GWP)5.4. Sources (Where do these greenhouse gases get emitted?)5.5. How are they related to our daily life?You can read the material below before class to get prepared for these questions.
Class Activity. Professor Minghui Diao
Methane is emitted during the production and transport of coal,
natural gas, and oil. Methane emissions also result from livestock and
other agricultural practices and by the decay of organic waste in
municipal solid waste landfills.
Properties of Methane
Chemical Formula | CHA
Lifetime in Atmosphere 12 years
Nitrous oxide is emitted during agricultural and industrial activities, as well as during combustion of
fossil fuels and solid waste.
In 2013, nitrous oxide (N2O) accounted for about 5% of all U.S. greenhouse gas emissions from
Agriculture. Nitrous oxide is emitted when people add nitrogen to the soil through the use of
Transportation. Nitrous oxide is emitted when transportation fuels are burned.
Industry. Nitrous oxide is generated as a byproduct
Properties of Nitrous Oxide
during the production of nitric acid, which is used
Chemical Formula NO
to make synthetic commercial fertilizer, and in
Lifetime in Atmosphere 114 years
the production of adipic acid, which is used to
make fibers, like nylon, and other synthetic
Carbon dioxide enters the atmosphere through burning fossil fuels
(coal, natural gas and oil), solid waste, trees and wood products, and Properties of Carbon Dioxide
also as a result of certain chemical reactions (e.g., manufacture of Chemical Formula CO2
Carbon dioxide is removed from the atmosphere (or
“sequestered”) when it is absorbed by plants as part of the Global Warming
biological carbon cycle.
Lifetime: ~200 years (could vary between 100-300 years)
Fluorinated gases : Hydrofluorocarbons (HFCs), perfluorocarbons, sulfur Properties of F-gases
HFCs, PFCs, NFZ, SF
hexafluoride, and nitrogen trifluoride are synthetic, powerful greenhouse
gases that are emitted from a variety of industrial processes.
Fluorinated gases are sometimes used as substitutes for
NF3: 740 years
stratospheric ozone-depleting substances (e.g., CFCs).
These gases are typically emitted in smaller quantities, but because
they are potent greenhouse gases, they are sometimes referred to
as High Global Warming Potential gases (“High GWP gases”).
Lifetime in HFCs: 1-270 years
Atmosphere PFCs: 2,600-50,000
Low level ozone (or tropospheric ozone) is an atmospheric pollutant. It is not emitted directly by car
engines or by industrial operations, but formed by the reaction of sunlight on air containing
hydrocarbons and nitrogen oxides that react to form ozone directly at the source of the pollution or
many kilometers down wind.
The atmospheric lifetime of tropospheric ozone is about 22 days, its main removal mechanisms
are being deposited to the ground.
The short lifetime of ozone (hours-days) precludes a meaningful calculation of global warming
potential on the time horizons (20, 100, and 500 years) listed in IPCC documents
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