In the past ninety days, the West Coast has experienced some exceptional weather and weather-related disasters. Some of the worst fires in Santa Barbara ís history struck that community in November, destroying homes and disrupting lives. Christmas snowfall hit record depths in the Pacific Northwest, followed by significant flooding of low-lying communities due to torrential rains on top of rapid snowmelt. Much of California is experiencing its driest January on record, and minimal snow blankets the Sierra Nevada, the prime source of water for the state's residents, its agriculture, and its industry.

All of these events are likely to be examples of the probable impacts of global climate change, now acknowledged by even the most cautious in the scientific community as both real and present. And it ís not happening just in the West. Consider the past few years: prolonged droughts in the southern plains and southeastern states; massive hurricanes in the Southeast and in Australia; bizarre snowfalls alternating with summer-like temperatures in the Northeast; record-breaking floods in New England, Europe, and elsewhere; rapidly melting glaciers and icepacks; and rising ocean temperatures.

But, what does this have to do with gardening on the West Coast? While earthquakes remain beyond our ability to control, or even predict, we all have the power to slow climate change and reduce its impact on the planet, even if only slightly, by the way we live, work, play, build, and garden. We can start by giving serious thought to how and when and in what manner we move about to accomplish our daily tasks; walking, biking, and riding public transit are far healthier alternatives to the private, single-passenger automobile, and substantially less damaging to the environment.

As gardeners, we can help reduce the use of fossil fuels by eliminating gas-powered equipment for mowing and trimming lawns, shearing hedges, and pruning trees. We can eliminate the use of chemical fertilizers, decreasing the quantity of pollutants released during their manufacture, and slowing plant growth to a more natural pace, thereby reducing the need to mow, shear, and trim. We can plant more trees, in our gardens and in our cities; scientists have long recognized the ability of trees to clean the air of harmful pollutants.

We can also take the longer view, aiming for a sustainability in our gardens. There are lots of ideas floating around about what that means in a garden. Let me explain how I consider sustainability as it relates to the responsible design and management of a garden.

It seems to me that there is a range of solutions to the design of a garden. At one end might be a garden of native plants, grown from locally collected seed sources, planted in native soils at the beginning of the rainy season (in California) At the other end is a garden of tropical plants growing in containers in a less-than-tropical climate (such as California ).

At the one end, only minimal inputs of energy and resources should be necessary to get the native plants established and to allow them to mature in the garden. At the other end, constant inputs are necessary to keep the plants alive. Yet, the solution of a container garden may be the only one available in the particular circumstance.

There are lots of variations, or gradations, between the two ends of this range of design solutions. Each one of the points on that scale of gradation has inherent pros and cons; tradeoffs that make a particular solution appropriate for the given situation.

A living roof, as one extreme example, takes a good deal of technological stuff, including manufactured materials, to make it function properly: protection for the real roof, lightweight solutions to holding the soil, systems for irrigating and removing excess water, systems for providing nutrients, monitoring during stressful times (heat of summer, perhaps cold of winter), systems for providing access for maintenance. But the tradeoffs are substantial: increased longevity for the roof, moderating interior temperatures, cooling the atmosphere, adding oxygen to the atmosphere, reducing runoff, providing habitat for wildlife, perhaps preserving species, and enhancing the aesthetics of the area. All of that, I think, more than balances the effort and energy that goes into creating and maintaining the living roof. The alternative solutions to that same roof offer virtually none of the advantages of the living roof.

The Academy of Sciences  The living roof

Each of the decisions in designing and maintaining a garden can be evaluated in the same way: what will be the overall impact of that choice of plants, paving materials, irrigation system, or pruning practice? If we consider each of those decisions against the ultimate positive or negative impact on our world, we might begin to make decisions that have the greatest positive overall impact, or that have the least negative impact.

We can not recover the human losses from landslides, floods, and fires that may be the result of changes in our climate. But perhaps there is still time for us to work together to slow the speed of global climate change while maintaining and enhancing the beauty in the corner of the planet we call home.

What have YOU done today to reduce climate change?