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 trapping heat and many can stay in our atmosphere for thousands of years.1

Figure 1:Source: The 2010 Assessment of the Scientific Assessment Panel, UNEP.

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 is used as the base for all the calculations, so its global warming potential is 1.2 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 lose their ability to trap heat.

The main processes that remove these gases from the atmosphere are chemical destruction by hydroxyl radicals, photolysis and reactions in the mesosphere.3 4 Three of the main high global warming potential gases have sinks that act extremely slowly, which is why they have such long lifetimes (more than 1000 years). From the human perspective, the emissions of these gases and the effects that they cause are essentially permanent. If the production of these synthetic gases is not reduced, the long-term increase of global temperatures will continue.

The table below shows the heat trapping ability of the important greenhouse gases after 20 years and 100 years as compared to Carbon dioxide. 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.

Table 1: High Global Warming Potential Gases

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

• 1. Montzka, S.A., S. Reimann, A. Engel, K. Krüger, S. O’Doherty, and W.T. Sturges. Ozone-Depleting Substances (ODSs) and Related Chemicals, Chapter 1 in Scientific Assessment of Ozone Depletion: 2010, Global Ozone Research and Monitoring Project–Report No. 52, 516 pp., World Meteorological Organization, Geneva, Switzerland, 2011.
• 2. Forster, P., V. Ramaswamy, P. Artaxo, T. Berntsen, R. Betts, D.W. Fahey, J. Haywood, J. Lean, D.C. Lowe, G. Myhre, J. Nganga, R. Prinn, G. Raga, M. Schulz and R. Van Dorland. Changes in Atmospheric Constituents and in Radiative Forcing. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 2007.
• 3. Hodnebrog, Ø., M. Etminan, J. S. Fuglestvedt, G. Marston, G. Myhre, C. J. Nielsen, K. P. Shine, and T. J. Wallington. "Global warming potentials and radiative efficiencies of halocarbons and related compounds: A comprehensive review." Reviews of Geophysics 51, no. 2 (2013): 300-378.
• 4. Levin, I., D. E. Worthy, D. Osusko, R. Heinz, T. Naegler, S. A. Zimov, R. Weller, L. P. Steele, C. V. Rohden, B. Neininger, R. L. Langenfelds, J. Ilmberger, A. Engel, and E. Cuevas. "The global SF₆ source inferred from long-term high precision atmospheric measurements and its comparison with emission inventories." Atmospheric Chemistry and Physics 10, no. 6 (2010): 2655-2662.