If the question is a bit confusing, what I'm asking is if there is scientific evidence to counter an argument against climate change that I had come across.
The person said that climate change is not a serious issue due to the "globe" having warmed up before in humanity's existence -- specifically Greenland during the Viking age, or the Nordic countries.
Addendum: I understand that such an argument against climate change is not factually correct, however, in the spirit of the scientific method I went to look for evidence that pointed either in favor or against this argument... only to then wade through a quagmire of pseudo science and nonsensical claims in favor of this response which are distressingly common. Thus I ask this question to try to get more clear information.