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Greenhouse Gas Levels Are Higher Than The Past 800,000 Years

June 9, 2017

In the most comprehensive collection of greenhouse gas measurements to date, a new report confirms that the most important greenhouse gases are rising drastically. The report states that atmospheric greenhouse gas concentrations are at record levels for the last 800,000 years. But what are the sources of greenhouse gases and what are their environmental impacts?

Greenhouse gases remain in the atmosphere for different periods of time due to differences in rates of decomposition and removal by sinks. Therefore, the radiative forcing of the gas or its capacity to affect that energy balance, thereby contributing to climate change, to varying degrees, with time.

Greenhouse gases enter the atmosphere through natural processes and human activities. The portfolio of natural processes includes above ground sources like animal and plant respiration and underground sources such as volcanic activities and sedimentary basins.

Human sources of greenhouse gas emissions consist of (percent of 2014 greenhouse gas emissions from anthropogenic activities):

• Electricity production (30 percent)

• Transportation (26 percent)

• Industry (21 percent)

• Commercial and Residential (12 percent)

• Agriculture (9 percent)

• Land Use and Forestry (offset of 11 percent) – sinks, the opposite of emissions sources and absorb CO2 from the atmosphere.

Carbon dioxide is also naturally present in the atmosphere as part of the Earth’s carbon cycle – the natural circulation of carbon among the atmosphere, oceans, soil, plants, and animals. Human activities can alter the carbon cycle—both by adding more CO2 to the atmosphere and by influencing the ability of natural sinks, like oceans and forests, to remove CO2 from the environment. While debates concerning the impact of elevated CO2 levels on climate change are slowly converging on agreement of CO2 induced global warming, public opinion seems to diverge on whether high levels of atmospheric CO2 are beneficial or harmful to plant life.

It is a fact that plant life depends on atmospheric carbon dioxide, light energy from the sun, water and nutrients to produce oxygen and sugars that builds roots, stems and leaves during photosynthesis. Without carbon dioxide, plants cannot get carbon and therefore, cannot live. Common logic then suggests that, as the level of atmospheric CO2 increases, so would plant growth. But is this true?

In Can Plants Overdose on CO2?,a survey of scientific studies investigating the impact of elevated levels of CO2 on plant growth, the author found agreement between investigators “that higher levels of atmospheric CO2 do increase plant growth when viewed only from the standpoint of CO2.” However, when other factors were considered, several investigations supported the opposing view that excessive amounts of ambient CO2 can adversely influence plant growth. These “secondary” factors – ambient temperature, local precipitation, soil condition, nutrient availability, and microorganism plant interactions – are the observable changes in weather patterns from accelerated atmospheric CO2 concentrations.”

Then where did the assumption originate that anthropogenic activities contribute to the rise in these GHG? Scientific America points out that that the human race “has subsisted for at least 200,000 years on a planet that has oscillated between 170 and 280 ppm of atmospheric CO2, according to records preserved in air bubbles trapped in ice.” Over the last 160 years, CO2 levels have risen above 400 parts per million (ppm). Thus, implying a direct relationship between the Industrial revolution, which began around 1760 to 1840, and increasing levels of atmospheric CO2. This finding is also substantiated by other indirect measures like “tree rings, glacier lengths, pollen remains, and ocean sediments, and by studying changes in Earth’s orbit around the sun,” per the EPA.

The rise of Industrial Revolution coincided with the railroad industry’s reliance on steam locomotives powered by a relatively inexhaustible supply of cheap coal rather than firewood and charcoal which were less efficient and in short supply. Around the same time, coal-fired steam engines made inroads in the maritime industry, as steamboats began to replace barges and flatboats in the transport of goods around the United States. By mid-19th century, petroleum started to make inroads as domestic oil refining provided abundant supplies of kerosene for lighting and heating homes and industrial facilities. Later petroleum made a huge impact on the transportation industry as oil drillers in America learned how to supply an endless stream of low-cost petroleum-based fuels – diesel and gasoline – that fueled the rapid growth of the automotive, shipping and aviation industries.

In late 2010, the U.S. EPA issued a report concluding that fugitive emissions from the natural gas system from wellhead to burner may be far greater than previously thought. These fugitive emissions are therefore a particular concern since it is the major component of natural gas. As such, small leakages are important. Fugitive leakage becomes even more important as natural gas serves a greater role in America’s energy mix. Currently, the EPA exempts the Oil and Gas industry from direct controls of natural gas discharges.

Global Warming Potential Of Greenhouse Gases

To keep a level playing field between greenhouse gases, which have different absorbance and atmospheric lifetimes, the International Panel on Climate Change developed a comparative measurement system called Global Warming Potential (GWP). GWP compares the ability of each greenhouse gas to trap-heat in the atmosphere relative to carbon dioxide, which accounts for about 82 percent of all U.S. greenhouse gas discharges.

Since the heat-trapping ability of a gas is compared to that of CO2, a measure called carbon dioxide equivalents is used to express its GWP. Carbon dioxide equivalents represents an amount of a greenhouse gas whose atmospheric impact has been standardized to that of one-unit mass of CO2, based on the global warming potential of the gas.

For example, if 1 pound of methane is emitted, this can be expressed as 21 pounds of CO2 equivalents by multiplying; 1kg of CH4 by 21, its global warming potential at 100 years, see Figure 10. In other words, one pound of methane has the equivalent heat-trapping ability as 21 pounds of CO2, after 100 years in the atmosphere. Note, there is international disagreement between the EPA and IPCC on the actual GWP of methane; ranging from a low of 21 by the EPA and a high of 34 by the IPCC. Recently, EPA revised the value to 25.

Figure 10: Relationship between the GWP of methane (CH4) and CO2




Reprinted compliments of,  June 1, 2017

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