Smell of pine vs climate change

That’s right: the smell of pine trees from boreal forests could mitigate the global warming — provided that the global warming doesn’t kill the forests first [1]. The volatile organic compounds (VOCs), responsible for the smell of pine, react with atmospheric oxygen to form aerosols. These aerosols scatter solar radiation and also act as cloud condensation nuclei, thereby affecting the Earth’s radiation balance. An international group including researchers from Finland, Germany, Denmark and USA has discovered a direct pathway leading from several biogenic VOCs, such as monoterpenes, to the formation of extremely low-volatility vapours (ELVOCs) [2].

These vapours form at significant mass yield in the gas phase and condense irreversibly onto aerosol surfaces to produce secondary organic aerosol, helping to explain the discrepancy between the observed atmospheric burden of secondary organic aerosol and that reported by many model studies. We further demonstrate how these low-volatility vapours can enhance, or even dominate, the formation and growth of aerosol particles over forested regions, providing a missing link between biogenic VOCs and their conversion to aerosol particles.

Structures of the main VOCs studied by Ehn et al. [2]

The air was sampled in Hyytiälä, Finland and the chamber experiments were conducted at the Jülich Research Centre in Germany.

1. McGrath, M. Smell of forest pine can limit climate change. BBC News, 26 February 2014.
2. Ehn, M., Thornton, J.A., Kleist, E., Sipilä, M., Junninen, J., Pullinen, I., Springer, M., Rubach, F., Tillmann, R., Lee, B., Lopez-Hilfiker, F., Andres, S., Acir, I.-H., Rissanen, M., Jokinen, T., Schobesberger, S., Kangasluoma, J., Kontkanen, J., Nieminen, T., Kurtén, T., Nielsen, L.B., Jørgensen, S., Kjaergaard, H.G., Canagaratna, M., Dal Maso, M.D., Berndt, T., Petäjä, T., Wahner, A., Veli-Matti Kerminen, V.-M., Kulmala, M., Worsnop, D.R., Wildt, J. and Mentel, T.F. (2014) A large source of low-volatility secondary organic aerosol. Nature 506, 476—479.