Consumer spending is falling fast. While that’s bad for the economy, it’s good for the environment. Excessive consumption produces waste and pollution streams that are destroying our planet. The question now is how are we going to respond to the economic crisis at hand. If our elected officials and business leaders seize the moment, the consumption downturn will ignite a movement that saves our economy and our environment for generations to come.

And maybe, just maybe we marketers will heed the call to help lead the way.

In the near term, an environmental benefit will be of little solace to those whose jobs depend on consumer spending, which is to say most of us since consumer spending comprises nearly two-thirds of our economy. It’s all-but certain the current financial crisis will slip into an economic recession, perhaps as rough as any we’ve experienced in decades.

As painful as the near future may become, the glass half-full view reveals the opportunity ahead. Financier George Soros explains:

You see, for the last 25 years the world economy, the motor of the world economy that has been driving it was consumption by the American consumer who has been spending more than he has been saving, all right? Than he’s been producing. So that motor is now switched off. It’s finished…You need a new motor. And we have a big problem. Global warming. It requires big investment. And that could be the motor of the world economy in the years to come.

Over consumption, made possible by easy access to debt, explains much of the financial mess we’re in today. And a consumer economy, stoked by cheap, abundant fossil fuels, is a principle cause of global warming. In the end, reliance on consumer spending is both bad for the economy and bad for the environment. Other than that, it’s great.

What makes the coming elections so critical is the next president and Congress will decide whether we as a nation will fundamentally change the underpinnings of our economy. If we simply find new ways to prop up our consumption-based economy, we will hasten the day of reckoning that climate change requires. If we embrace the environmental and social challenges of climate change as the economic opportunity of our times, we can all look toward the future with hope.

For marketers, the opportunity is to finally begin leading the world in the right direction. If “the motor of the world economy” has been consumption, the fuel has been marketing. Marketers create awareness and demand for goods, services and ideas. The problem is we’ve used our talents overwhelmingly in support of unsustainable economies, employers and clients.

But that can change. Imagine if we were to unleash our creativity and persuasive abilities in service to freeing our economy from dependence on fossil fuels and mindless consumption. I’m convinced the impact would be both enormous and swift for our climate, environment and economy.

I don’t know whether the collective parts of the marketing industry — branding, advertising, PR, direct marketing etc. — are up to the task. The industry is so deeply enmeshed in the profitable, but dead-end ways of consumerism. So be it. The train is leaving with or without us. In the words of Thomas Paine, our choice is simple: “Lead, follow, or get out of the way.”