Aerosols

http://www.ucsusa.org/global_warming/science_and_impacts/science/aerosols-and-global-warming-faq.html#.VgmSgstViko

http://climate.nasa.gov/news/215/

https://www.esa.int/esaKIDSen/SEMP4LXJD1E_Earth_0.html

http://www.earth911.com/living-well-being/health/the-aerosol-can-debate-continues/