You seem to have misunderstood the trend in polar bear populations: there are several groups that have populations in decline, and some that are increasing. The groups with increasing populations are mainly in Canada, and the reason for their increase is because of new laws protecting polar bears from hunting, which is completely detached from the issue of climate change.
Also, the earth is indeed getting greener, and global greening is positive, but it won’t halt climate change — just slow it somewhat.
I don’t quite understand what you were trying to say with regard to sea levels — your figure of 3mm per year only seems to corroborate my point.
Of course, climate change is not an absolute certain disaster indicator — but you appear to have missed the point of the article. It was to say that, although we might not die, the ecological impact of climatic change is far greater than plastic pollution, and we ought to refocus on the larger and more threatening environmental issue.