On my email accounts, I have filters that keep out most spam. But my regular mail boxes at home and the office? No such luck! Advertising arrives in the post daily, by the sheaf and by the ream.

It annoys me. Here I am, scrupulously recycling and contemplating the climate impacts of my consumption, while L.L. Bean and its ilk are dropping slabs of paper in my mail box: paper that took carbon-storing trees to create, climate-polluting factories to mill, and carbon-belching trucks to haul. All told, it’s 41 pounds of junk mail a year per American.

Admittedly, junk mail isn’t high on Cascadia’s lists of menaces. According to estimates developed for the US Postal Service, it accounts for just over one tenth of one percent of all energy use (at least, if Cascadia matches the US average), plus one-fiftieth of municipal solid waste.

Still, it’s worth a little attention, especially when you consider that virtually no direct mail actually works. Postal advertising is an industry where a mass mailing is considered successful if 2 percent of envelopes or catalogs generate a sale. That means 98 percent of the paper and ink was pointless waste. If we could wave a magic wand and make it disappear, both the mailer and the recipient would be better off.

Look at the situation from an entrepreneur’s perspective. Any industry where 98 percent of the marketing misses its audience is a gargantuan business opportunity for whoever can figure out how to boost the “hit rate.” Eliminating unwanted ads in our mailboxes should increase profits for mailers by slashing costs without diminishing revenue. After all, US merchants pay upwards of $30 billion a year to produce and distribute junk mailings, and less than half of it even gets opened. Better targeting of direct mail aligns the interests of the economy with those of forests, the climate, solid waste agencies, and postal customers. What a deal!

The environmental implications of junk mail—most of which are caused by paper production and disposal—are worth spelling out. This report by a group of national environmental organizations says that, among US manufacturing industries, papermaking is the first-ranked consumer of water (per ton of product), third-ranked consumer of energy, third-ranked emitter of toxic pollutants into the air, fourth-ranked emitter of greenhouse gases, and fourth-ranked emitter of toxic pollutants into water.

Paper’s climate impacts are particularly troubling: From our forests—which absorb and store carbon dioxide, slowing climate change—to the landfill, the paper trail disrupts the climate. Two of every five trees felled around the world by loggers (as opposed to land-clearing farmers) are destined for pulp and paper mills. (The United States, the world’s junk mail capital, uses more paper per person than any other nation ever.) Paper accounts for one fourth of municipal landfill waste, and municipal landfills account for one third of human-caused methane emissions. Methane is 23-times more potent a greenhouse gas than carbon dioxide. All told, according to this calculator by Environmental Defense, paper generates three times its weight in carbon dioxide and other greenhouse gas emissions.

Those 41 pounds of junk mail have the same carbon footprint as burning six gallons of gasoline. (And remember, that’s 41 pounds per member of your household.)

But how to seize this waste-reduction opportunity?

Two solutions:

Federal or state “Do Not Mail” registries, like the “Do Not Call” registry for telemarketing. The Center for a New American Dream has been campaigning for such services. Fourteen states, including Cascadian states of Washington and Montana, have considered legislation to create state “Do Not Mail” registries—plus fines for those direct mailers who ignore them. (To support the bills, write your representatives here.) In Canada, by policy of Canada Post, citizens can simply inscribe on their letter boxes “No advertising mail, please” and be spared much of the deluge. Unfortunately, this policy just results in letter carriers throwing out junk mail rather than householders doing so. Canada, too, needs Do Not Mail lists. (British direct marketers themselves have agreed to boost the precision of their targeting in order to trim waste.)

In the meantime, we can all take ourselves off of various mailing lists. Here are three good guides for ways to stopadvertisingmail. Or you can pay a small fee to a junk-snail-mail filter service like 41pounds.org or greendimes.org to have them do the leg work.

My own favorite is the new, free service CatalogChoice. It’s signed up more than 300,000 members in its first three months of operation. For me, it’s fun to throw the unwanted catalogs on a pile and, whenever I feel like it, log in to my account at Catalog Choice and zap my name off the relevant lists.

Or, at least, ask for my name to be removed. As BusinessWeek reports, not all catalog mailers are honoring Catalog Choice yet. I predict they’ll come around soon enough. As Catalog Choice’s membership grows, it’ll have substantial power to cajole, embarrass, or pressure mail-order businesses into compliance. And with or without merchants’ cooperation, Catalog Choice builds the political case for official Do Not Mail registries.

P.S. One counterargument that I’ve heard for junk mail is that direct mail allows postal services such as Canada Post and USPS to achieve bigger economies of scale: they can maintain inexpensive nationwide service for all. Were it not for the plethora of catalogs and credit card offers, goes the argument, it might cost a dollar to mail a baby photo to your faraway uncle. It’s a plausible argument, but it appears to be false. US law governing the postal service stipulates, for example, that “each class of mail or type of mail service bear the direct and indirect costs attributable to that class or service.” In other words, your baby picture is already supposed to pay its own way.

Still, for the sake of argument, let’s assume it’s true that junk mail helps pay for real mail. That still wouldn’t justify the practice! Ponying up a little more to mail a letter would be a small price to pay to unspam our mail boxes.

(Alyse Nelson did most of the research for this post. Thanks, Alyse!)