Concern over climate change rose to a fever pitch in 2006 after the release of Al Gore’s documentary An Inconvenient Truth, and around the same time, the concept of carbon neutrality burst into public consciousness. Could people and businesses offset their carbon footprint by investing in projects, from capturing or burning off methane from livestock or landfills to reforestation and avoided deforestation, that prevent or capture greenhouse gas emissions?

Almost as soon as carbon neutrality took off, though, the concept was skewered, most famously by journalist George Monbiot, who compared carbon offsets to the Catholic Church’s Middle Ages practice of selling indulgences. Monbiot wrote that offsets would sidetrack society from the more urgent need to reduce fossil fuel use and merely assuage people’s guilt over their lifestyle, resulting in continuation of the status quo. His premise seemed to resonate with people and the idea spread.

But in 2007 Grist columnist David Roberts railed against Monbiot’s analogy, which he called a “transparent smear.” “[If] it was the aggregate amount of sin that mattered rather than any individual’s contribution, and indulgences really did reduce aggregate sin,” Roberts wrote, “then indulgences would have been a perfectly sensible idea.” And, Roberts wrote, despite a lack of evidence that people buy offsets to assuage guilt over an opulent lifestyle while neglecting other behaviors that benefit the environment, that argument was “just stated, over and over again, as though it is axiomatically true. … What is the personality profile of the guy who buys offsets and then considers his work done? I’ve never met him and have trouble envisioning him.”

But what, then, is the personality profile of an individual who offsets carbon? For three of the past five years, I have calculated and then offset my carbon footprint. I engage in many other energy-saving behaviors, but am not willing to live in a cave. Still, I’m a rarity even among climate-concerned folks. And I have often wondered: Had Monbiot and others not so effectively panned offsets, creating mass skepticism over their effectiveness (and the intentions behind those who use them), how many tons of greenhouse gases might have been eliminated by people like me?

“I think of my own small efforts to cut my emissions as the climate change version of the ‘First Rule of Holes,’ which is: If you find yourself in a hole, the first thing to do is to stop digging.” – Environmental journalist Nancy Bazilchuk

Looking for others who offset their carbon footprint proved challenging — perhaps not surprising given that individuals comprised only 1 percent of the voluntary offset market in 2010, down from 5 percent in 2006. A World Bank report [pdf] valued the voluntary offset market at $569 million in 2011, with around 87 million metric tons of carbon dioxide equivalents traded, primarily from businesses and nonprofits interested in corporate social responsibility. The much larger “compliance market,” in which companies and governments purchase carbon credits to comply with caps on the amount of greenhouse gas emissions allowed under the Kyoto Protocol and other climate policies, was valued at $175.5 billion in 2011, with 10 billion metric tons CO2e traded. But the price of carbon has dropped substantially, raising concern over the future of the market.

It turns out, at least with those to whom I spoke, individuals who offset their footprint voluntarily do feel some guilt associated with their lifestyle, but contrary to Monbiot’s argument, all engage in additional environmentally conscious and energy-saving tactics, whether riding bikes, buying a hybrid vehicle, recycling or eating less meat. Since completely eliminating their footprint is nearly impossible in the modern world, all expressed a desire to do something more to help what they consider a global environmental and social problem.

“I know that the amount of carbon dioxide and other greenhouse gases that we are putting into the atmosphere is going to cause us all a great deal of trouble as … global temperatures increase and sea level rises,” says environmental journalist Nancy Bazilchuk, a U.S. citizen living in Norway. “I think of my own small efforts to cut my emissions as the climate change version of the ‘First Rule of Holes,’ which is: If you find yourself in a hole, the first thing to do is to stop digging.”

Though Bazilchuk was surprised by the low cost (“I can’t believe I can dispense with all my guilt for just $20 per transatlantic flight,” she says), she has concerns over whether offsets can make a difference. A series in the Christian Science Monitor in 2010 harshly criticized a handful of the carbon-reduction projects supported by offset purchases, expressing concern over the concept of “additionality” — whether these projects actually reduce emissions in a way that would not have occurred otherwise. Nevertheless, the reporting did not address how common these cases are among the thousands of projects that exist