Express your personal commitment to do something about global climate change by riding your bike or walking to town on Saturday instead of driving your car. The organization 350.org has designated this weekend as a time for people around the world to express their resolve to address this problem.

The name 350.org derives from the fact that we need to lower the concentration of carbon dioxide in our atmosphere from 390 parts per million to 350 parts per million in order to maintain some semblance of the global climate we enjoy now. The concentration of carbon in our atmosphere is directly related to the rate at which we use fossil fuels.

Decreasing this rate will be no mean achievement. Even if we maximize our production of renewable energy, the likelihood that we will be able to produce enough to supply our current usage is very slim at best. Fossil fuel is still by far the cheapest and highest-density energy source that we have. We will have to adapt to a far lower rate of energy use, and it will require major changes in our economy and lifestyle.

Adding urgency to our need to act is the fact that global oil production is at or near its peak. The implications of this are that from this point on, oil will be more and more expensive and hard to get. Building the infrastructure we need to provide renewable energy will require oil. The longer we wait, the more difficult and expensive it will be.

Even if you think that my appraisal of the situation is alarmist and exaggerated, you probably agree that petroleum is a finite resource with far more valuable uses than as fuel. Is it right for us to fritter away this wealth, leaving nothing for those who come after us?

How do we lower our energy use? To start, we can learn a lot from our neighbors in Europe. If the United States had the same energy use per capita as Europe, we would be a net energy exporter. How do the Europeans do it?

For one thing, they have smaller, more efficient houses. A much larger factor, I believe, is how they transport themselves. They have a modern and well-developed regional and urban mass transit infrastructure, high-speed interurban trains well linked to urban subway systems. They also use bicycles to a great extent for practical, everyday transportation.

Bicycling is great for health, way more fun than a convertible, good for communities and a great way to address our energy problem. Think of biking as not just fun, but a great practical tool in your lower-energy profile.

Ride to town this weekend. If you don’t have a basket or panniers for your bike, bring a backpack to carry your Farmer’s Market produce and cider home. If you live farther away from town than you care to ride just yet, think about parking a mile away (parking in town on Saturday is awful anyway), and riding in from there. Tell your friends. Let’s see if we can put a dent in that Saturday uptown traffic jam.

— Terry Sullivan is a self-employed woodworker and community activist

Transition Vashon, a group organizing Saturday’s bike ride, has formed to communicate a sense of urgency and hope about adapting to the challenges the community faces and focus the community’s talents and energy toward creating a plan for a more self-reliant, efficient and resilient Vashon. Contact Terry Sullivan at 463-2812 or terry.sullivan46@gmail.com. To find out more about the transition movement, visit transitionnetwork.org.