In academic circles the debate is scientific.
As in: is it getting warmer on average?, can we say that's a climate change or is it another kind of structural change in our average weather situation?, and if so, what part of it is man-made? Arguments are based on data and backed up by models; datasets are being questioned, data filtering is being questioned, models are being questioned. Things work as they should, and the current majority opinion among scientists is: yes, global warming is most definitely happening, and yes man probably has a large part in that.
As soon as politics comes into it, the debate becomes political and thoroughly commingles the question "what's going on?" with "what are the consequences if global warming is happening?" and "suppose we all went onto an austerity programme, how much help would that be in practical terms, and would it be cost-effective (supposing that global warming is man-made)?".
What you see is a split between people who argue: yes global warming is happening and it's a valid reason to tell everyone (else) what to do in terms of conserving energy and scrapping their SUV's (roughly coinciding with the "centre-left").
And between people who think "we're not going to let a bunch of hippies tell us to change our lifestyle, so we'll attack the basis on which their demands rest, which happens to be global warming. (the "far right"). Those people are known as "climate-change deniers" and are conducting a totally different debate.
Their debate is about the question "Are we going to allow others to use this global warming scare as lever with which to impose measures on people that just so happen to coincide with their (centre-left) political agenda anyway?".
They obviously don't want that, and apart from denying obvious facts they are searching for ways to discredit people who provide those facts. That's a lot easier than debating facts anyway, and those are the ones you hear calling for private emails from researchers they don't like.
Where private citizens get into it, the debate splits even further along political lines. Citizens tend to follow politicians and opinion leaders they like and will defend what their chosen opinion leaders say and attack those opinion leaders they don't like. Simple. For such people it's not about facts (they wouldn't know how to check them anyway) but about credibility and ... who they would like to be on top come next election. Nothing new here, but that particular debate was never meant to be "scientific", so we shouldn't wonder that it isn't.
So it all depends on what debate you mean: the one among scientists, the one among politicians, or the one among citizens.