Global warming forced primarily by anthropogenic CO2 is a hypothesis. (realclimate.org)
Wilmking et al 2004 Recent climate warming forces contrasting growth responses of white spruce at treeline in Alaska through temperature thresholds Global Change biology 10: 1724 (deepclimate.org)
As long as warming forces like greenhouse gases are present, the resulting radiative forcing can extend drought - like conditions more or less indefinitely, says MacDonald, a distinguished professor of geography and of ecology and evolutionary biology at UCLA. (mediarelations.uwo.ca)