Himalayan balsam, the non-native plant, is “so bothersome that Royal Marines have been called in to try to eradicate it, and so persistent that a top laboratory is working on a biological “secret weapon” to defeat it.” Entirely our own fault of course: not just the Victorians liberally sprinkling its seed but botanical outlets of our own era marketing ““Mr Noisy’s Exploding Plant” as a novelty for children.” One redeeming hope: “all parts of the plant are edible.” (http://www.independent.co.uk/news/science/himalayan-balsam-call-the-marines-itsan-alien-plant-invasion-8723024.html)
Given that “we need 2,500 kilocalories (kcal) each per day … the world’s total edible crop harvest could supply 4,600 kcal per person per day. However, of this 1,400 kcal is lost or wasted. A further 1,700 kcal is used as animal feed. But – crucially – the resultant meat and dairy products only provide 500 kcal for human consumption.” (http://www.eating-better.org/blog/3/Feeding-nine-billion-how-much-extra-food-do-we-need-to-produce.html)
If we put less of our global food crop into overeating, the bin and animal feed, we could feed the projected population of nine billion in 2050.
Also perhaps we don’t need two billion extra people.