The Anthropocene

Apparently this is my week to read things that get my dander up. The Economist has a nice little story up about global warming beginning 5,000 years ago thanks to agriculture. They reference a paper that I can't read yet, as it is still in press, so I don't exactly know what it says, but the author, Bill Ruddiman, argues elsewhere that the Anthropocene (the Geologic age defined by Humans becoming dominant contributors to geologic cycles) should start with the spread of agriculture, 5,000 to 8,000 years ago rather than in 1784 with the invention of the steam engine (see here for a quick summary of the argument between Ruddiman and Paul Crutzen). The Economist story isn't a bad story, actually, for its brevity.

Then come the comments. In them, the same tired, "humans can't really influence climate/global warming isn't real/it's a natural cycle/where were the humans to cause the end of the last ice age/pick your favorite duplicitous misrepresentation of science" were trotted out, refuted, and re-trotted. Why, when scientists argue amongst themselves about the minutia of our fields, is that argument immediately taken as proof that what we say is wrong? The argument here is not whether or not global warming is real, is happening, is significant; but rather the argument here is whether anthropogenic forcing of the climate began earlier than most scientists (and non scientists!) suppose. It's an argument over definitions, and boundaries, and ultimately over what is considered significant. I realize it may be difficult for a non-scientist to catch all of what's going on in a quick blurb (and realistically, anything less than a book is probably a quick blurb), but seriously, could we employ our brains for just a few moments and examine what we're reading logically? Is an article that ends with,

So although the size of the effect has increased markedly since the industrial revolution, it looks as if humanity has been interfering with the climate since the dawn of civilisation.

really a great one to support the "global warming isn't real" mantra?