This Monday, the BBC published an article on the elephant in the room of environmentalism - population control.
Basically, if the planet has a limited capacity then the more people there are the less they can consume each. At some point, there will be a requirement to match the number of people to consumption - and this will not necessarily be peaceful.
So, the article looked pretty sensible and rational, and then I got down to the comments... is the BBC trying to make North Americans look like frothing paranoid bigots, or could they not find enough frothing paranoid bigotry from the English (looking at the standard have your say comments, frothing paranoid bigotry really isn't in short supply in the UK), as the barking mad of the prairies were in full swing - "They're coming for our babies!". Oh dear. Fortunately, reading further down, the Obama-voting regions of the US demonstrated that sense and logic aren't strangers to the New World.
This is why this is such an emotive subject, and one that scientists will struggle with. Scientists are trained to deal in facts. Gather facts, build a hypothesis. If the hypothesis doesn't match the facts, can it be modified to do so? If not, abandon the hypothesis (admittedly some scientists are very loathe to abandon their favourite hypothesis)
However, not everyone is a scientist. Particularly on the internet, the model is opinion first, then find facts to back them up. Stop digging as soon as you find something that looks like a fact, even if it isn't (especially if it isn't, as digging more might damage it). If you can't find one, make it up, although finding one that someone else has made up means you can at least imitate the appearance of scientists by putting cites in. That, sadly, is the model that dominates on comments pages on websites such as the BBC and Guardian.