But the place where you hear this most is with the genetically modified stuff. As you may be familiar with, biotechnology and hybrid strains of crops curbed famine throughout the developing world. The Green Revolution was not without flaws. None of them quite equal the tragedy of the millions of people who would starve or go hungry without the food security offered through better crops.
New GM crops, and biotechnology and better farm tech more generally, offer another quantum leap in this direction. But people end up hating these ideas, and the rationales typically involve fallacies of the excluded middle. GM crops don't preclude supporting whatever other communal farm structure you prefer. Nor are they a panacea; nor is anyone claiming they are.
The argument goes "We don't need GM because we already grow enough food in the world--it just goes to feed fat Americans!" Again, there is, of course, no reason we can't grow more food in the developing world and get Average Joe to cut back.
But the reality is that Joe won't cut back and we don't really want him to. In the whole of human history, when has any population willingly cut back its food consumption to altruistically favor another on a sustained basis? Are we going to let such an event--which has never before happened--dictate our food policy? On top of that, should we say that this strategy should preclude the private pursuit of any other tactics to curb malnutrition?
And take a closer look at what this really entails. It calls for America--a heavily developed industrialized country--to permanently send food to primarily agrarian poorer countries. Nations of farmers will now become dependent for their basic survival on food imports from countries where agriculture accounts for a fraction of the economy. This isn't viable, and it's puzzling that anti-imperalist leftists would even think of this as an option. Moreover, the bigger reason why people can't get enough to eat is because they don't have enough money. Giving farmers the tools to raise more crops and earn more solves this problem as well as plenty others. Putting in a food pump from Iowa to Djibouti does not. This is why so many people are focusing on ending trade barriers to farm goods in developed countries.
After all of this, you typically hear some sort of neo-Marxist "sustainable" talk that goes like "This will cause all sorts of problems in the long run!" Well, keep in mind that the long-run isn't just some spot in the distance. The long-run is now, for policies enacted a long time ago. If these sustainability arguments hold any water, we should observe some pretty dire outcomes where industrialization and heavy agriculture came in some time ago. Yet, looking around, I don't see that--I see farm yields highest and the environment cleanest in countries which did all of those horrible things a long time ago.
Of course there are some problems out there. I find that the solutions which seem to make sense center around pricing inputs better; extending property rights; and promoting innovation and technology. Useless fear-mongering isn't doing anyone any good--least of all the farmers who might actually use better seeds and technology (or not--give them a choice!). Count this as reason million-and-one why we need rational environmentalists.