The feedback issue is just such a question as is the allocation of the late twentieth century temperature rise between its plausible causes. (judithcurry.com)
Specifically, the urgent issue before us is whether or not observed late 20th century solar activity is causally linked to late 20th century temperature rise and will a decrease in activity in the 21st century induce cooling. (informthepundits.wordpress.com)
i.e. therefore tree rings are useless as a proxy to show that 20th Century temperature rises are unprecedented, and that there was no Medieval Warm Period, since they apparently don't respond to increases in temperature. (climate-resistance.org)