Social psychological research has shown that on any number of topics – from capital punishment, to gun control, and the like, such as nanotechnologies people squeeze new evidence through powerful social and cultural filters. Pouring facts into this filter system does not necessarily produce consensus and it can even cause attitudes that lead to polarization. So the answer is not to lay facts in before the non-believers in a discussion on climate change and like topics. The educated and non-educated will come out of the discussion with the same beliefs that they went into the discussion and most times even stronger beliefs.
So what is the answer or method to use if you do believe that global warming or climate change is a fact? I believe the best constructive method in dealing with an individual who may be in denial is to stay calm, stop quoting facts for they have been set before the individual many previous times and the individual has filted them to arrive at his/her conclusions. In discussion with such a person be Socratic in method by throwing back within the discussion questions instead of stating an additional fact. Answer each statement made by the individual who you feel is in denial with an additionally directed question pertaining to the subject at hand. This will allow the adversary you are having the discussion with to arrive at conclusions without necessarily filtering facts through the filter system that they came to the conversation with.
By the use of the Socratic method of debate one simply answers questions or statements with questions. You by the use of the Socratic system of debate have allowed your adversary to form their own conclusions. Many times this is done by the adversary without the use of the filter system that he or she came into the discussion with.
You will not win every time, however allowing the individual that you are speaking with who may be in denial I have found at a minimum a mind may be somewhat preyed open.