«A potential does exist for significant positive feedback» from Arctic Ocean clathrates, warned Bell (1982), who was stimulated by a 1980 paper presented by Gordon J. MacDonald, see MacDonald (1980). (history.aip.org)
The total climate impact of forest losses in the north is still uncertain, Flannigan said, but if the peat lands in Russia and Canada continue to dry and burn more often, «there could be a significant positive feedback.» (scientificamerican.com)
What is more we know with certainty that there are significant positive feedbacks — water vapor, decreased albedo, etc.. (realclimate.org)