Greenhouse gases consist of chemical compounds and make up a significant portion of the atmosphere. These gases act as insulation for the Earth and trap heat radiated by the Sun that would otherwise be sent back out into space. Without certain gases in the atmosphere, life would not have been able to evolve on Earth to what we see today.
Greenhouse Gases in Our Atmosphere
- Water Vapor (H2O)
- Carbon Dioxide (CO2)
- Methane (CH4)
- Nitrous Oxide (N2O)
- Ozone (O3)
Water Vapor (H2O)
Water vapor is the most abundant gas in our atmosphere. This gas is more affected by the feedbacks of climate change such as increased temperature rather than direct impacts. This is because as temperatures warm, more water is evaporated from surface sources such as rivers and oceans, and becomes humidity in the air. The more concentration of water vapor in the air, the more thermal energy it will absorb from the Earth, therefore increasing the temperature even more. Higher temperatures will cause more water to evaporate and thus result it what is know as a ‘positive feedback loop’.
Carbon Dioxide (CO2)
Carbon dioxide is regulated in the atmosphere through the carbon cycle, which affects the hydrosphere and biosphere as well. Parts of the carbon cycle include plant photosynthesis and decay, and the absorption of the gas into the oceans. The carbon cycle is currently unbalanced due to 3.2 billion metric tons of the gas being released into the atmosphere yearly as a result of human activity (http://www.eia.doe.gov).
Methane is naturally introduced into the atmosphere through the decay of organic material. As a result of human activity such as the burning of coal and oil, unbalanced and excessive amounts of methane are introduced into the atmosphere. Methane is effective in absorbing radiation but has a lower atmospheric concentration than CO2 and a shorter life span (about a decade).
Nitrous Oxide (N2O)
Nitrous oxide is released into the atmosphere after being produced by microbial processes in water and soil. The gas is also released during industrial operations such as the burning of fossil fuels and vehicle emissions.
Ozone is located in the stratosphere above Earth and is composed of oxygen and ultraviolet radiation. Humans are responsible for creating an additional ozone including carbon and nitrogen molecules as a result of pollution. These molecules, when hit by sunlight, create an ozone layer. The ozone layer is thicker in more urbanized areas due to a greater amount of pollution.
Gases within this category are not produced naturally and are completely synthetic. This type of gas was introduced in the late 1920’s when used in aerosols and cleaning products (http://www.ncdc.noaa.gov). A danger posed by chlorofluorocarbons is that they have been proven to damage the stratospheric ozone layer. These gases have a fairly long atmospheric lifetime that can last well over 100 years. Since the discovery of the damaging effects to the ozone, global changes have been made to stop the production of chlorofluorocarbons.
Effects of Greenhouse Gases
Although greenhouse gases are natural elements occurring in our atmosphere, humans have altered the levels to dangerous amounts. Since the Industrial Revolution, carbon dioxide emissions have risen substantially due to the burning of fossil fuels, and extraction and use of other natural resources. The impact of greenhouse gases is magnified because when released into the atmosphere; they will build up and remain present in large amounts for tens, hundreds, and potentially thousands of years. This increase of greenhouse gases can be directly linked to the present issue of climate change and loss of biodiversity as a result of human activity.
Increased levels of greenhouse gases have impacts on the temperature, which in turn has affects on the pollution in the air. Warmer temperatures result in more smog in the atmosphere. Rising carbon dioxide levels in the atmosphere also cause plants to create more pollen resulting in more allergens, and dry barren landscapes become more susceptible to wildfires. These environmental changes pose threats to people by irritating eyes, throats, and even causing lung damage. Many states across the United States are now putting in place air monitoring programs to measure the air quality and to prepare for future changes.