Westeros as we all know is modeled after Medieval Europe, and many characters are modeled after real life people, and the War of the Five Kings is modeled after the War of the Roses. But in the end, Game of Thrones is still fantasy, and fantastical elements must be brought in. However, just because something is fantasy, does not mean it has some truth in it. And me and other people have come up with a theory that the White Walkers are metaphors for a real life threat that threatens the real world and everyone living, Climate Change/Global Change.
George RR Martin wrote the first book in the 90's at a time when Climate Change/Global Warming was not considered a serious threat, and then Al Gore released An Inconveniant Truth and suddenly Climate Change/Global Warming was on everyone's tongues. Some(including me) began changing their ways of living in order to save the only world we have. But others denied it's existence, calling it a hoax, propaganda, and even worse a conspiracy.
Now in relation in Westeros, no one has seen or heard from the White Walkers in thousands of years and at the start of the series they are not considered a threat by the Northerners. But the Andals outright refuse to believe they exist. Then Jon learns of their existence and tries to warn people. So far, only the inhabitats of the North(Who due to their worship of the Old Gods seem to be more environmentally cautious) seem to believe him and is preparing for war against them. But the Andals might prove harder to convince.
What ultimatly does make Game of Thrones? More bigoted people might begin to say it's propaganda. More cautious people might call it a metaphor for fighting among ourselves while ignoring real threats that could end us all?
Naw. The first three books were modeled after Wars of the Roses like you said. Also, like you said global warming and what is now called "climate change" because the earth shows some eveidence of cooling trends in areas and Antarctica is actually getting thicker...my point is, climate change is a better word. Having ramblied on about that, I do not think the WW are a metaphor for climate change as they showed up in book 1 and I was in high school and part of college then and I really don't remember people talking about it at all. AnInconvenientTruth wasn't published in 2006 and 10 years later it's being called "infamous" and "Alarmingly inaccuarte", and so on so I really hope he didn't base it off that, which I doubt he did for the reasons above.