The long term problem is when the "Childfree Movement" becomes mainstream.
Wrong, the true long term problem is if the "childfree movement" doesn't become more mainstream, especially in India, Indonesia, and Brazil.
The earth is at 6 billion people and growing fast. India is set to over-take China in population by 2045.
With global warming along with fewer fuel reserves, it is only going to be more and more challenging to feed everyone. Sure, global warming will make more northern lands more hospitable for food growth -- to bad most northern land doesn't have the soil needed -- while at the same time desertification of southern lands is increasing every year.
The looming fresh water wars, as most of the world does not have access to adequate fresh water will be the next problem.
Every environmental problem can be traced back to one cause: over-population. Global warming: too much CO2 as a result of too many people consuming fossil fuels, felling forests, and reclaiming massive carbon sinks such as peat bogs. Peak oil: too many damn greedy humans consuming as much as possible not realizing that fossil fuels are non-renewable. If this entire planet contained only 1/2 the number of people, every one of those people would be much more comfortable and better off.
You may think that Canada is immune to this, and in some ways you are right. Our population growth rate is barely high enough to replace ourselves, but the rest of the world is by far doing that for us. An ever expanding world population is only going to mean more and more people will want what we have here -- land and fresh water, and in the future they will do anything to get it. They will come -- legally or not. Have a read of Gwynne Dyer's Climate Wars --
http://www.amazon.ca/Climate-Wars-Gwynne-Dyer/dp/0307355837 -- very interesting, I hope it doesn't come true, although some of it already is -- massive droughts in large parts of the world, massive flooding in others. The future really is looking scary if you bother to open your eyes to it.
So, saying all that, there are many very good reasons why I shouldn't have kids:
1. Adding to the global population will not solve any problems, in fact it will only aggravate them.
2. Plenty of people are already having kids and many immigrants are coming that will fund my pension and staff my nursing home if I make it that long.
3. Why would I want to subject a kid to a life where they will very likely have less than I have, just like I will likely never have as much as the baby boomer generation has?
I remember reading once that if Indonesia with a population of 242 million and a very high population density decided to institute a draft and invade Australia (so much open land!), they would have more soldiers than Australia has bullets. Now consider China, India, Brazil, and just imagine the massive armies that could soon be colonizing the world for it's fresh water and arable land.
And before too many disregard Gwynne Dyer as a fear monger for his above mention book, consider this quote that I took from one of the reviews of the book:
This publication is primarily based on military strategies based on projections of climate change, strategies created by credible sources like the US military and the pentagon. These Strategies (one of the more famous called, "the age of consequence") are not the work of, "a spaced out out hippy," but of militarized powers, analyzed by a renowned PhD Military and Middle Eastern History commentator - who publishes a weekly column in several international newspapers.
Oh, and before any breeder starts worrying about my genetic line carrying on, consider this:
I am from a family of 8 kids who already have 14 spawn. My Dad is from a family of 9, my Mom from a family of 13 -- so I have 20 blood related uncles and aunts (40 including marriage). Those uncles and aunts have, on average, 6 kids per family... so I have roughly 120 cousins who almost all have kids of their own now. I think my bloodline has done enough to overpopulate this planet!