What are High Global Warming Potential gases?

Hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) are the main High Global Warming Potential gases. Many of these gases are 1000, 10 000 even 20 000 times more powerful than Carbon dioxide (CO₂) at traping heat and many can stay in our atmosphere for thousands of years.

It is important that we discuss what is meant by High Global Warming Potential (HGWP). Global Warming Potentials (GWPs) are used to compare the abilities of different greenhouse gases to trap heat in the atmosphere. Carbon dioxide (CO₂) is used as the base for all the calculations, so its global warming potential is 1. The higher the GWP, the more heat the specific gas can keep in the atmosphere. So the more HGWP gases enter the atmosphere, the faster our climate will change.

As time passes the GWP of a greenhouse gas usually decreases, but as is the case with fluorinated gases since their global warming potential is already very high it takes a very long time for them to break down and lose their ability to trap heat. What's worse is that since these fluorinated gases are created exclusively by humans and are not normally found in nature, there is no natural process or "sink" to remove these gases from the atmosphere slowly over time. The table below shows the heat trapping ability of the important greenhouse gases after 20 years and 100 years as compared to Carbon dioxide (CO2).

Table 1:

Source: Climate Change 2007: the Fourth Assessment Report (AR4), Intergovernmental Panel on Climate Change.

The reason why we should look at the GWP of greenhouse gases is to highlight the fact that even if there is a small quantity of a specific gas, it doesn't mean we shouldn't take into account the effects that it has on climate change. As previously mentioned, there isn't a large quantity fluorinated gases emitted annually. In fact, as we can see in figure 1, carbon dioxide is by far the greenhouse gas that is the most produced.

Figure 1:

Source: Inventory of U.S. Greenhouse Gas Emissions and Sinks (2008), EPA.

But in table 1 we saw that some gases are so good at trapping heat that many are 1000, 10 000 even 20 000 more powerful than CO₂. So if you take into account the GWP of each greenhouse gas you get a completely different picture. In figure 1 we can see that if the volumes of each gas are indexed against their global warming potential, the impact of fluorinated gases (which account for only 2% of emissions by volume) is actually far worse than their raw volume would indicate. That small volume of Fluorinated gases is responsible for 87% of the extra heat trapped on Earth, which has a huge impact on climate change. Fluorinated gases are very powerful greenhouse gases as we can see from this short analysis and have an important role with respect to climate change.

Figure 2:

Source: Inventory of U.S. Greenhouse Gas Emissions and Sinks (2008), EPA. Climate Change 2007: the Fourth Assessment Report (AR4), Intergovernmental Panel on Climate Change.

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