The SOA computed variability results from a 7 % increase in biogenic VOC emissions from 1986 to 1990 combined with 8.5 % and 6 % increases in the wet and dry deposition of SOA and leads to about 11.5 % increase in the SOA burden of biogenic origin. (pubs.giss.nasa.gov)
Based on carbon isotope analyses the methane is of biogenic origin. (slideplayer.com)