This Vlogbrothers video was published in September 2013 and is one in which Hank Green provides counterarguments to common ideas that people who don’t believe in climate change use to defend their standpoint. He begins the video by describing what climate change is and why it’s a problem that we, as humans currently living on this earth, should care about. And then he contextualizes his arguments with data and figures from peer-reviewed scientific papers. All of these papers are linked in the video description, so viewers can read about The Myth of the 70s Cooling Consensus or A Reconciled Estimate of Ice-Sheet Mass Balance, showing that the land ice mass (as opposed to the sea ice mass) of Antarctica is decreasing with time.
The audience is primarily the Nerdfighter community (those who regularly watch Vlogbrothers videos), which vary from teenagers to adults in their 40s who accept Hank Green as a reliable host and generally are open to listening to his opinions. As with all YouTube videos, though, his ideal target audience is anyone on the website. This video is accessible and well-made enough for many types of people to find it at least somewhat engaging, from those who are familiar with vlogs and many formats of online video, to those looking solely for entertainment, to those who use YouTube for educational videos, etc.
Overall, I think the video is effective for an audience that either 1) agrees with climate change 2) slightly disagrees with climate change for no really strong reasons or 3) a casual audience who has very little knowledge about the subject. The fact that he uses figures from scientific papers to back up his verbal claims and summarizes the rest of the literature in his argument works for this medium, a <4 minute YouTube video for people (especially younger audiences) who just want to get more informed.
However, this video will probably fail to persuade firm believers in “global cooling” that climate change exists. I’m assuming that these types of people are less likely to do further reading in the suggested papers and might not even listen to the entire video before starting discussions, productive or otherwise, in the comments. At best, this video might persuade them to doubt one or two of the misconceptions they have about climate change, which might count as having successful impact.