Fully 72 % of adults say there is solid evidence of warming, while a quarter (25 %) say there is no solid evidence of this. (pewinternet.org)
The scientists interviewed did say that while this is clear evidence of warming they said that more research is needed to directly attribute it to anthropogenic global warming. (realclimate.org)
The same sort of farming seems to have been possible for much of the intervening time, therefore the farming can not be taken as direct evidence of warmer conditions. (skepticalscience.com)