It wasn't 20 years ago today, but close enough: About this time in 1990, my book, "The Green Consumer," hit the bookstores. The book -- the U.S. version of a 1988 U.K. bestseller, "The Green Consumer Guide," by John Elkington and Julia Hailes, which I substantially adapted for U.S. audiences -- began with a simple premise:

"You probably don't realize it, but every week you make dozens of decisions that directly affect the environment of the planet Earth. At work, at home and at play, whether shopping for life's basic necessities or its most indulgent luxuries, the choices you make are a never-ending series of votes for or against the environment."

I went on to note that: "The marketplace is not a democracy; you don't need a majority opinion to make change. Indeed, it takes only a small portion of shoppers -- as few as one person in 10 -- changing buying habits for companies to stand up and take notice."

From that opening gambit sprang 340-odd pages of overviews, insights, advice, lists and sidebars (including one cheery piece titled "How the American Way of Life Is Destroying the Earth"). And from that book sprang 1,001 magazine articles, syndicated columns, newsletters, speeches, interviews, panel discussions, books, reports, websites and more that have been the centerpiece of my professional life over the past two decades.

The world has changed dramatically over those 20 years. There's the Internet, for starters, as well as 500-channel cable TV, social media, globalization and the rapid growth of emerging economies, the current Great Recession notwithstanding. Environmental issues have gone from the margins to the mainstream. School kids, young adults, their parents and even some politicians today are well-versed in environmental problems, if not their solutions. And more and more companies continue to be engaged in more and more ways, addressing and reducing their environmental impacts. Many companies are going beyond that, creating innovative new products and services designed for a low-carbon economy.

But one thing hasn't changed all that much: green consumers. That is, there don't seem to be that many more today than in 1990, in terms of people making significant changes to their shopping and consuming habits in ways that move markets toward greener products and services, never mind actually "saving the Earth."

I won't bother to make the case that consumers -- in the U.S. but also elsewhere -- say one thing and do another. I've harped on that theme relentlessly over the years. (See examples here, here, here, here and here, among many others.) Suffice to say, the chasm between green concern, as expressed by consumers to market researchers, and green consumerism, as reflected in real-life purchase of products and services, remains vast, as much today as in 1990.

True, there are successes. In the cleaning products aisle, Method and Seventh Generation now compete to scrub market share from the likes of Clorox and Procter & Gamble. FedEx and UPS compete vigorously on who can deliver greener operations. So, too, Dell and HP, Coke and Pepsi, and a handful of other leading brands that compete to see who is greener. The notion of big companies competing, at least in part, on environmental performance represents progress, no question about it.

But all of this represents only a tiny fraction of the economy, and little of this is driven by consumer demand. Consumers, for all their good intentions, don't really want to change. They want what they want -- and what they feel they need and deserve -- with little regard for where it comes from, how it's made, how it's used and its impacts throughout its lifecycle.

To be sure, consumers haven't been overwhelmed with green choices. While hundreds of major companies have reduced their impacts in ways both large and small, few of their achievements are visible on supermarket shelves. As I've written in the past, the aluminum can containing a third less aluminum than its predecessor, the laptop computer that has eliminated toxic flame retardants, and the bag of snack food whose manufacturer now recycles its rinse water, all represent tangible environmental improvements. But these companies aren't typically messaging those achievements. Indeed, they're not even undertaking these measures to "save the Earth"; they're doing them because they save money, reduce risk and liability, improve quality and delight employees — and maybe win them a few reputational points.

That is to say, they're doing these things for all the right reasons.

The result: We've all become greener consumers in spite of ourselves. The stuff we buy is greener than it used to be, sometimes significantly so, even though its producers don't necessarily tout their achievements.

All of which raises the question: Are green consumers even necessary? Is much of this marketing and labeling activity a waste, a distraction from the business of running an eco-efficient business?

It's an open question. As I've mentioned in the past, green marketing represents a reputational risk for most big companies. Consumers, activists, bloggers and others are quick to dub things as "greenwash" when environmentally imperfect companies make green claims. That has led many companies to engage in, for lack of a better term, covert environmentalism, burying mentions of their green deeds in their websites or corporate responsibility reports, rather than tout them on products or advertisements and risk the wrath of critics.

I'm not quite ready to proclaim green consumerism dead (though I can't honestly say it's ever been alive and well). There will always be a small corps of true-blue green consumers ready to vote with their dollars -- at least for some products. But my 20-year-old premise -- that a relative handful of committed consumers will transform companies and markets -- hasn't really panned out, though I still believe it to be true.

What will green consumerism look like over the next decade? Will we be celebrating or mourning green consumerism when Earth Day 2020 rolls around? And if the former, how will we have gotten there? I welcome your thoughts.