Lester Brown is one of those who bother to say that if humanity keeps its present (narrowly defined) course it will soon collapse. I proclaim with the same level of assurance that if I keep typing letters at the present rate I will collapse before midnight.
Fortunately, "courses" look quite different when we define them less narrowly. I practice the good habit of changing tasks before collapsing. People tune their behavior to the circumstances. Society adapts to changing conditions.
Things change all the time. Except Lester Brown. For more than 30 years he has kept predicting worldwide food shortages and high food prices. Food has become more abundant and cheap because people have changed the way they grow food. Lester Brown hasn't changed his mind about the impending collapse. Marginal Revolution has more on a Bill McKibben article in The Washington Post reporting and endorsing the apocalyptic pronoucements of Lester Brown's latest book (if you click the link you will help Marginal Revolution) and points to an older post of The Daily Ablution about Brown's past statements and an appearance in The Independent (which has just co-won the Wooden Spoon prize for worst environmental reporting in the UK, awarded by EnviroSpin Watch).
International wheat prices adjusted for inflation (from the Government of Canada):