Many concerned and informed people feel guilty over their carbon footprint. Buying carbon offsets lets them assuage this guilt, but this is a misguided perspective. Instead, I suggest we promote climate stewardship with policies that steadily encourage energy conservation and low CO2 production, e.g., carbon taxes.

Individuals atone for their “excessive” carbon consumption, i.e., twenty room houses and private jets, by buying carbon offsets. This behavior has a religious analogue. The buying of these offsets reminds me of the purchases of indulgences, a practice perfected by Pope Leo X in the early 1500s.

Pope Leo X was extremely generous with various charities and education. At times his spending was nearly tenfold the Vatican’s revenue. These spending habits, and a love of “the good life,” precipitated financial disaster. In response to financial pressures, Leo developed a new funding strategy—selling indulgences.

Many members of Catholic orders, those in monasteries for example, sinned little and performed a great many religious deeds. Hence, they built up a large positive balance in their heavenly accounts, far more than required to avoid purgatory, Catholics’ wait station to heaven.

Many laymen would also like to skip purgatory. Being entrepreneurial, Leo asked, why waste the blessings earned by those in religious orders? He devised a system that transferred the positive balances of those in holy orders to individuals deficient in heavenly credits. A person could offset sin, for example, by contributing to building or refurbishing churches. Among the many useful things Pope Leo X did under this scheme was rebuild St. Peter's Basilica.

For the Pope and wealthy Catholics, this was a great system. If one were sufficiently rich, he could buy his way into heaven. There was no outside auditor of indulgences.

Conceptually, it’s an easy step from indulgences five centuries ago to carbon offsets today. Carbon offsets offer an unguent for global warming guilt. The February 27, 2007 edition of Business Week describes “the carbon footprints of famous people who are for sustainability and against global warming … (but) live in many very big houses, drive many very big cars and fly in private jets. The World Economic Forum in Davos was "carbon neutral," despite all these folks flying in to attend, because in large part, people donated money to third world countries to plant trees or build hydroelectric dams for electricity.”

As George Monbiot observed in The Guardian: “Rejoice! We have a way out. Our guilty consciences appeased, we can continue to fill up our SUVs and fly round the world without the least concern about our impact on the planet. How has this magic been arranged? By something called “carbon offsets.” You buy yourself a clean conscience by paying someone else to undo the harm you are causing.”

I don’t know if indulgences worked as advertised, but buying CO2 offsets is promising—but only if honestly and accurately designed and applied. If being profligate with CO2 is a transgression, then ameliorating the excess surely is a virtue. For example, if one takes a pleasure trip by auto or aircraft, it may make social and ecological sense to buy a reduction in CO2 from an existing source, say a dirty coal fired power plant in China.

But there are many flaws in this scheme. What amount of CO2 production is excessive? Driving a Hummer to ski Bridger seems excessive, while given the environment in which they operate, the Bridger Canyon Fire Department’s Hummer is an appropriate emergency vehicle. There are also huge problems inherent to measuring, monitoring, and enforcing an offset system, especially in corrupt regimes.

Problems of equity and honesty will surely emerge. For example, America could offset all its industrial emissions by buying carbon credits in the developing world. Surely someone in the environmental justice movement will craft an analogue to the 95 theses that Luther nailed to Wittenberg’s door in 1517.

Successful environmental stewardship requires policies that actually achieve stated goals. While some carbon offsets are a step in the right direction, they are surely no substitute for the hard choices and tradeoffs we will eventually face.