Origin of Global Warming Potential
With the development of ESG, regulators in various countries have made many regulations on greenhouse gas emissions of companies. The common greenhouse gas is carbon dioxide, while methane and nitrogen compounds are important monitoring items. Carbon dioxide accounts for more than 60% of the total greenhouse gas emissions, so many laws and regulations restrict carbon dioxide emissions.
So, how should regulators measure the effectiveness of methane, nitride and other gases? The Global Warming Potential (GWP) was created to solve this problem. In simple terms, GWP can be regarded as a measure of the effect of these gases on carbon dioxide (set as unit 1) in the process of global warming, that is, different gases have different GWP values. The larger the GWP, the more obvious the effect in the greenhouse effect.
Calculation and Publication of GWP
The calculation results of GWP are published by the United Nations Intergovernmental Panel on Climate Change (IPCC). As GWP will change over time, the calculated values of IPCC are also divided into three categories: 20 years, 100 years and 500 years. The most commonly used is the 100-year GWP, which represents the effect of other gases on the greenhouse effect relative to carbon dioxide based on the 100-year time span.
IPCC first published GWP values of a series of gases in 1995, and then published new GWP calculation values again in 2007 and 2014. Due to the continuous improvement of calculation accuracy, the three GWP values are also slightly different. At present, the GWP value in 2014 is relatively widely used. However, in some regulatory policies, the 1995 version is also used because of the high popularity of the earlier version.
For example, in the 1995 version, the GWP value of methane relative to carbon dioxide is 21, that is, methane produces 21 times the greenhouse effect of carbon dioxide over a 100-year time span. In 2007, the GWP value of methane was revised to 25, and in 2014, it was revised to 28. The GWP values of nitrous oxide in the three measurements are 310, 298 and 265 respectively.
From the calculation of GWP, we can see that the greenhouse effect of methane and nitrogen compounds is significantly higher than that of carbon dioxide. In fact, the GWP value of some fluoride far exceeds this standard. For example, in the 2007 version, the GWP value of sulfur hexafluoride reached 22,800, and its greenhouse effect was 22,800 times that of carbon dioxide. This is why fluoride has long been prohibited in the regulations of many countries.
Reference:
2.10 Global Warming Potentials and Other Metrics for Comparing Different Emissions
