Global Warming Potential of Methane

The earth is heating up, the ozone layer is depleting, we need to reduce industrial and domestic toxins, etc. are the common phrases that we hear very often. So, we hardly take any notice, unless some devastating natural disaster occurs. Climate change, and not for the better, is a harsh reality. Global warming and its impact on human, plant, animal and the overall climate has been studied for years now. The greenhouse effect is influenced by the percentage of the greenhouse gases present in the atmosphere among other things. Greenhouse gases include carbon dioxide, ozone, nitrous oxide, methane and water vapor, of which carbon dioxide is the main culprit in global warming. However, new research indicates that methane's global warming potential is as damaging as other gases.

Global Warming Potential (GWP)

For years together, the link between global warming and carbon dioxide has been studied. But now, people are realizing that methane is also a potential cause for global warming. GWP is a measure of the quantity of a given mass of greenhouse gas which is estimated to contribute to global warming, and the subsequent greenhouse effect. It is calculated over a specific time interval, and all values must be stated in regard to GWP. The scale of the specific gas is measured based on the heat-absorbing ability of each gas to that of the same mass of carbon dioxide. The emission of these gases are subjected to the Kyoto protocol.

Why Does Methane Have a GWP?

Species	Chemical formula	Lifetime (years)	GWP 20 yrs	GWP 100 yrs	GWP 500 yrs
Methane	CH4	12±3	56	21	6.5

Source: Climate Change 1995, The Science of Climate Change: Summary for Policymakers and Technical Summary of the Working Group

Methane is a chemical compound found in the atmosphere and listed as one of the greenhouse gases. According to a study conducted by NASA Goddard Institute for Space Studies, New York, emissions of methane have a profound impact on global warming. Methane has enormous global warming potential because its impact has been calculated about a third higher than previous estimates. Previous estimates did not take into consideration methane's interaction with aerosols (airborne particles). Methane breaks down much faster than carbon dioxide, thereby increasing the probable negative impact on the earth's climate. Aerosol interactions with methane substantially alters various emissions of other gases, thus, lending a lot of credence to its GWP. Global warming potential values are assigned as it facilitates a standard mechanism to compare the impacts of emissions and reductions of different gases. For example; methane's GWP of 21, indicates that it is approximately 21 times more heat absorptive than carbon dioxide, per unit of weight. The value is also important to evaluate and study climate change mitigation strategies of the direct and indirect effects of emissions.

Methane is linked to all other greenhouse gases, and as studies now indicate that its emissions have a larger impact than that used in current carbon-trading schemes, or in the Kyoto Protocol. This threat needs to be taken seriously, as global warming is a very worrying environmental issue. Methane is the second most important greenhouse gas produced after carbon dioxide by human activity, and accounts for nearly a fifth of global warming effects. Methane is about 21 times more potent than carbon dioxide at warming the earth. In the atmosphere, methane is short-lived, for about 12 years. As it is emitted in the atmosphere due to industrialization and development, we can probably curtail its emitted quantity by working towards a clean source of energy.