4 reasons why urban landscapes are a linchpin for climate resilience
When it comes to water sustainability and climate resilience, urban outdoor landscapes represent a wealth of opportunity.
Outdoor landscapes are a vital component of our cities. Whether it’s outside a home, a store, an office, or a manufacturing plant, the landscape is a property’s primary interface with the community and the environment. Properly designed and managed using sustainable landscape strategies, these outdoor areas can help communities weather droughts, mitigate floods, sequester carbon, improve human well-being and more.
- Building healthy soils
- Preserving vegetative cover
- Using climate-appropriate plants
- Conserving water and other resources
This could include strategies such as removing turf, building rain gardens or installing permeable pavement or rain tanks.
To achieve sustainability, we need to make some changes
Take California, my home state, as an example. California has notoriously variable precipitation patterns, and this is increasing with climate change. We are seeing longer and hotter droughts, and more intense storms; and more dramatic fluctuations between these two extremes. This means that our cities are facing increasing threats of water shortage on one hand, and flooding on the other.
Our current urban landscapes, marked by big lawns and paved areas, don’t do much to alleviate these problems. In fact, in many cases, they exacerbate them. Thirsty turf grass requires a lot of irrigation, especially in the peak of summer when it’s dry and hot, and water is in shorter supply. Over half of urban water use in California (PDF) goes to landscape irrigation, and that portion is higher in the summer. Vast expanses of pavement — parking lots in particular — leave no place for rain water to go but down the drain, which has limited capacity to handle intense storms, leading to flooding and pollution.
There is a better option
We can turn our urban landscapes into assets for climate resilience, rather than a source of risk. For example, look below at this side-by-side case study of two residential yards in Santa Monica, California (sustainable landscape on the left, traditional landscape on the right). Nine years of monitoring both landscapes showed that the sustainable landscape uses 83 percent less water, creates 56 percent less green waste and requires 68 percent less maintenance than the more traditional landscaping.
Sustainable landscapes can provide a multitude of benefits (PDF), but I’ll focus on four themes here: drought; flood; carbon; and community.
Sustainable landscapes are resilient to droughts
There are two key ways that sustainable landscapes can make urban communities more resilient to drought: using less water, and capturing water to use later.
Replacing grass with climate appropriate plants (and irrigating those plants properly) can reduce a landscape’s water needs by 70-80 percent. During the last California drought, we saw homes across the state doing this, a trend significant enough to be clear on Google Maps. This was a big part of why California’s urban communities were able to meet, and in fact exceed, the emergency drought mandate of reducing water use by 20 percent.
Sustainable landscapes also can be designed to capture water and hold it — in the soil, groundwater, or rainwater catchment systems — for future use. Building healthy soils allows water not taken up by plants to infiltrate into the landscape, and even down into groundwater aquifers, rather than running off and being lost down the drain. Similarly, rain barrels and tanks can capture roof runoff, which then can be applied back onto the landscape when it’s needed. Research shows that applying these approaches across southern California and the San Francisco Bay Area could increase local water supplies (PDF) by 20 billion gallons each year, roughly the amount of water used by the city of Los Angeles annually.
Sustainable landscapes help reduce flooding and water pollution
As the climate warms, California is experiencing more precipitation in the form of rain (versus snow), and these rain events are growing in intensity. Our urban areas, particularly those in southern California, will need to better prepare for these storms, and in particular improve flood management. As discussed above, sustainable landscapes are great at capturing and holding water; this is also useful formitigating local flooding. If water can run into rain gardens and soak into the soil, that means less water pooling on streets, parking lots and sidewalks. Beyond designing existing green spaces to hold flood waters, reducing the amount of paved area and replacing it with permeable paving or more green space can greatly contribute to local flood reduction.
These strategies also help prevent water pollution in our oceans and stream, because sustainable landscapes can absorb and purify the "first flush" of a rain event, which contains the most polluted water (carrying all the grime and contaminants from our city streets).
Sustainable landscapes sequester carbon and reduce greenhouse gas emissions
Water, energy and land use management are all intertwined and deeply connected to climate. Healthy soils rich in organic matter, a key component of sustainable landscapes, can sequester carbon from the atmosphere, providing climate mitigation. Sustainable landscape practices also can reduce energy use (and associated greenhouse gas emissions) because they require less mowing, blowing and green waste hauling than typical grass-dominated landscapes. There is also the energy embedded in water (PDF) to consider — less irrigation (through climate appropriate plants and capturing water for reuse onsite) means less water that needs to be collected, treated and transported to a landscape.
Sustainable landscapes improve community well-being
Finally, sustainable landscapes provide benefits to human-scale benefits to communities, beyond helping them weather droughts and floods. Switching from outdoor areas dominated by grass and pavement to ones with beautiful native plants and expanded natural spaces improves our well-being. For example, research shows the employees who have access to sustainable landscapes at their workplace are happier and more productive. In addition, sustainable landscape practices (especially replacing pavement with rain gardens) can help combat the urban heat island effect, a public health threat growing worse with climate change.
Transitioning to sustainable landscapes in cities around the world requires innovation and collaboration
The challenge (and opportunity) of achieving resilience to droughts and floods, reducing carbon emissions and fostering community well-being is one faced by cities around the globe. These are imperative and deeply interconnected issues, and urban landscapes lie at a critical nexus among them all.
With urbanization increasing rapidly, and climate change impacts manifesting more prominently every year, the call to action is becoming more urgent. Tackling this multifaceted challenge will take the efforts and collaboration of diverse urban stakeholders, from residents, businesses, scientists, city governments and on-the-ground change makers. At the Pacific Institute, a nonprofit organization focused on water and climate, we have been working for over 30 years on advancing innovative solutions for water-smart cities, including sustainable urban landscapes.