Recently, especially in dealing with subjects like near-earth-objects or global warming, I’ve come across more and more people whose reaction to these subjects is conditioned by or based on what I’d call the “vastness illusion.” I’m not talking about unintelligent individuals, either, but people who have been highly successful in business, academia, and in other fields requiring education, skills, and experience.

Put simply, the vastness illusion is the belief that the earth, and especially our solar system, is so vast that nothing we as human beings do could possibly affect it in any measurable fashion.

Like many illusory beliefs held by humans over history, there’s a grain of truth behind the vastness illusion. In fact, there’s nothing that a given individual — unaided by technology and the efforts of others — can do that will make a measurable impact on our world. For better or worse, however, there are six billion humans now living on the face of the planet, and those six billion people and their technology, both high and low, do have a significant impact on the world and, in particular, on its climate.

Those six billion people rely on 3.3 billion cattle, sheep, and goats for milk, meat, wool, and other products, and those billions of head of livestock require food, most of it derived from grazing. Presently, over half the grass and rangelands are at least moderately degraded as a result of the more than doubling of livestock production over the past century. Human activities, mainly those associated with agriculture, have increased annual methane emissions from less than 80 million tons in 1860 to over 500 million metric tons a year at present, and those emissions remain in the atmosphere for an average of 12 years, and they are a greenhouse gas that helps warm the atmosphere.

The six billion people and their activities are also adding 30 billion tons of carbon dioxide, another greenhouse gas, to the atmosphere every year, and the majority of that CO2 remains in the atmosphere for close to a century. Both these greenhouse gases have feedback effects on the water vapor that is and has always been the largest greenhouse gas in terms of impact. Even a slight increase in global temperature results in more water vapor. So while the advocates of the “vastness” theory point out that CO2, methane, and other greenhouse gases are “marginal” in their direct contribution to global warming, they tend to ignore their considerable feedback impact on water vapor, which is anything but marginal.

Admittedly, the earth’s atmosphere is indeed vast, but human technology and human numbers multiply our effects on the world, in a real fashion analogous to compound interest. A percentage point here and another one there, and millions have trouble making their house payments. Well… the same is true about human impacts on our planet… except that if we lose a climate conducive to maintaining our present human cultures, we lose a great deal more than a few million houses, and it’s a different kind of arrogance to insist that our activities have no impact.

The earth is over four billion years old, and yet, in the last few centuries we’ve managed to consume between a third and half the fossil fuels created over that long span… and the earth is too vast for us to have any impact? We’ve hunted scores of species out of existence, and we can make no difference? The levels of carbon dioxide in the atmosphere are the highest in more than 650,000 years, and that’s been with no large or sustained unusual natural occurrences; the last eleven years have been the among the 13 warmest over the past century and a half… and possibly the longest “warm streak” in thousands of years, if not longer; the northern polar ice cap has been shrinking steadily for forty years, and now is at the smallest extent and thickness in thousands of years, if not longer.

Yet, there are those who insist that the earth is too vast for us to have any measurable impact. What sort of impact do they want before they’re convinced? All of Florida under water? Starvation of billions because of climate shifts? Or would anything matter, because they believe that we’re essentially helpless to affect matters one way or the other?

I suppose that’s comforting, in a way, because it means we can do anything we want without having to be held accountable. Just claim that earth is too vast for us to be responsible, as well as being so vast that we can’t change or affect any major challenge that nature hurls at us. And, of course, that means admitting that, as a species, we’re merely hostages to fate, unable to direct our destiny, poor lost souls, depending on chance or deities to rescue us from disaster. But then, since neither chance nor deities have had a very good record in that department, if the majority of homo sapiens cast their lot with those who claim earth is too vast for us to affect matters, they’re essentially condemning the rest of us to great privation and possibly even marginalization or extinction as a species — and sooner, rather than later.

Not only does that make for lousy government and cultural direction, it’s also a terrible plot for either science fiction or fantasy.