If the argument had been presented in a factual way, I'd probably take it seriously, but since it was politicized and the exaggerations were deliberate attempts to deceive, there is no reason whatever to take the argument seriously. There are all kinds of threats, this may be one of them. But I'm not about to pay attention to some liar that is only looking out for his own wealth.
As to changes in climate, so what if China and India and similar emerging nations are causing a problem? What are we supposed to do about it? They are going to do what they need to do for growth and advancement, just as the US and Europe did. Just because we polluted the hell out of everything before they did and then changed our ways it doesn't make us right to pressure other countries to revert to primitive societies.
Despite the expansion of Chinese industry in recent years, they have been a heavy polluter for decades. It's not new, so any consideration of China's contribution to world air pollution will have to be in the context of incremental effects.
The credible science, after you wade through all the BS of which there is a lot, is that climate is changing, man probably has an impact on it, but it is not known how much, and that CO2 is probably not as big a factor as some would have us believe. Developed nations can reduce world emissions by taking the lead on low-emission energy production methods like nuclear power. They can also negotiate with emerging nations to learn from lessons previously learned to use more earth-friendly methods of expansion, and maybe help with the process.
The important thing is that change occurs on a longer scale than our own lifetimes, and it's easy to be blinded to what is normal by focusing on a few things. Keep in mind that Greenland, now under miles of ice, was a good place for agriculture and livestock only 1100 years ago. Florida had mastodons on it. The poles were in different places not that long ago. Wyoming was under the sea.
With all the hysteria, lies, and misinformation, we get statements like "the ice pack in the arctic has receded in big areas". The response should be "So what? Is that a problem? It's happened before, so why should we consider it an emergency if it happens again?"