A decrease in atmospheric methane levels might have triggered the progressive rise of atmospheric oxygen about 2.4 billion years ago, but the cause of this methane decrease remains uncertain.
Links:
[1] http://admin.indiaenvironmentportal.org.in/feature-article/oceanic-nickel-depletion-and-methanogen-famine-great-oxidation-event
[2] http://admin.indiaenvironmentportal.org.in/category/author/kurt-o-konhauser
[3] http://admin.indiaenvironmentportal.org.in/category/author/ernesto-pecoits
[4] http://admin.indiaenvironmentportal.org.in/category/author/stefan-v-lalonde-et-al
[5] http://admin.indiaenvironmentportal.org.in/category/journal/nature
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/marine-ecosystems
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/oceans-and-seas
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/atmosphere-and-ozone-layer
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/atmosphere
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/green-house-gases