Yet another greenhouse gas!

I was speaking on a panel in Oxford last week and the subject of greenhouse gases other than CO2 came up with one of my fellow panelists. It seems we can add a “new” one to the list of recognised greenhouse gases, Nitrogen Trifluoride. NF3 has a global warming potential (GWP) some 17,000 times that of CO2 with an estimated atmospheric lifetime of about 700 years. Like many of these high GWP compounds, NF3 finds a home in the electronics industry. It is not a listed Kyoto gas.

Global production of NF3 has grown from some 100 tonnes in 1992 to an estimated 4000 tonnes in 2007 and is projected to reach 8000 tonnes a year by 2010. The electronics industry tells us that only a very small (~2%) of global production is released into the atmosphere and that most industrial processes result in its destruction. However, not all observers agree on such levels (claims of up to 16% released).

Neverthless, the issue here is not NF3 itself, but the much more important need to keep a check on all the greenhouse gases. This point was really driven home for me when the Shell scenario team submitted the two Shell Scenarios, Scramble and Blueprints, to analysis by the MIT Integrated Global System Model of the Joint Program on the Science and Policy of Global Change.

Just a quick scenario synopsis first:

  • Scramble sees the world taking a more reactive approach, first focussing on increasing the energy supply and then facing the consequences later.
  • In Blueprints, the difficult decisions are taken sooner rather than later, leading to revolutionary changes and a better balance of economic and environmental needs.

The analysis is described very thoroughly in the MIT paper The Influence on Climate Change of Differing Scenarios for Future Development Analyzed Using the MIT Integrated Global System Model. In Blueprints the emission of non-CO2 gases is kept in check at about current levels whereas by 2100 the same gases under Scramble are some two and a half times current levels and still rising, even though Scramble has finally managed to see CO2 emissions plateau by the second half of this century.

The impact on atmospheric concentration of GHGs is even more marked. By 2100 Blueprints sees CO2 levels in the atmosphere plateau at about 550 ppm and total GHGs plateau at 630 ppm CO2e. In Scramble, CO2 is nearing 700 ppm and still rising, but total GHGs are now over 1000 ppm CO2e and rising. The latter translates into a near quadrupling over the 21st century of the net radiative forcing due to all long-lived GHGs, sulfate and black carbon, aerosols, and ozone which translates again to an increase, by 2100, in the Global Mean Temperature in degrees Centigrade (relative to 2000) of some 4.5 deg.C.

Whilst even the concerted mitigation efforts of Blueprints may be insufficient overall, the stark message of the analysis is “watch out for the other gases”. As we head towards Copenhagen, all eyes will be on the energy sector and CO2 emissions. NF3 and its cohorts may well miss the party, but to our long term detriment.