The last two decades witnessed a surge in adopting local and state open space protection laws and strategies. These techniques are now being examined as capable of protecting and enhancing the sequestering environment, which captures and stores from 15 to 20 percent of the nation’s carbon dioxide emissions.

This blog post is adapted from my articles Shifting Paradigms Transform Environmental and Land Use Law: The Emergence of the Law of Sustainable Development and Managing Climate Change Through Biological Sequestration: Open Space Law Redux.

Part of the local environmental law movement of the past twenty years involved the development of a robust body of open space preservation law implemented through local regulations and the acquisition of land or development rights by state and local governments and land trusts. Open space initiatives generally protect undeveloped lands for a variety of purposes ranging from viewshed protection to preserving ecosystem services. This body of law is now available to preserve and expand the natural resources that sequester CO2 in ways that mitigate and adapt to the consequences of climate change in both urban and rural areas.

Biological sequestration of CO2 emissions occurs within the vegetated environment: places like forests, pastures, meadows, and croplands. These landscapes naturally absorb and store carbon. According to EPA estimates, biological sequestration offset approximately fourteen percent of total domestic CO2 emissions in 2011. Most biological sequestration is due to carbon uptake and storage by forestlands, with pastures, meadows, cropland, and urban forests contributing as well.

Open space preservation law emerged in response to countless local perturbations: the loss of some cherished landscape feature, the gradual decline of visible open space, surface water or groundwater pollution, increased flooding, or the disappearance of valued wildlife, among others. Under express or implied legal authority delegated by their state legislatures, local governments have adopted a variety of laws that involve open space protection or management. These include environmentally sensitive area designation; erosion and sedimentation control; standards for grading, filling, drainage, soil disturbance, and removal of vegetation; floodplains control; natural resource management; watershed, groundwater, watercourse, and wetland protection; landscaping requirements; ridgeline, steep slope, scenic resource, and shoreline regulation; stormwater management; timber harvesting regulations; and tree protection and canopy expansion programs.

A variety of traditional and novel land use techniques are employed to preserve and enhance these resources. They include open space components of comprehensive plans, conservation district zoning, standards added to site plan and subdivision regulations, low impact development requirements, imposed conservation easements, transfer of development rights, cluster development, and density bonuses.

Land trusts are beginning to recognize the importance of carbon sequestration as they establish priorities for the acquisition of land or conservation easements. Some simply attribute a value to sequestration as worthy of consideration in deciding which lands to acquire. Others use detailed sequestration metrics in analyzing the purchase of a property or the creation of an easement. The Nature Conservancy has purchased several thousand acres as part of an initiative designed to utilize the sale of carbon offsets to make sustainable management practical.

Under New Zealand’s Emissions Trading Scheme, forest landowners who can demonstrate increases in the sequestration capacity of their properties receive a carbon trading credit for each ton of CO2 sequestered by these increases. These credits are tradable within the Kyoto Protocol. Participants submit maps of carbon accounting areas on their property to the Ministry of Agriculture and Forestry that demonstrate increases in forested areas on their lands. The Ministry uses a geospatial mapping system to instruct landowners how to calculate these increases. Once a landowner’s submission is confirmed, the Ministry allocates trading credits to the participant’s account. This example suggests that a cap and trade program could be used to encourage local governments to protect and enhance forested areas, aided by national technology resulting in economic incentives to regulated property owners.

In the years ahead, these efforts need to be brought to scale, particularly when the objective is to achieve a goal as ambitious as climate change mitigation and adaptation. As the population grows, more food will be needed, putting pressure to convert sequestering resources such as forests, meadows, and grasslands in rural areas to farmland. It is in these places that land use law can be particularly effective in designating and protecting properties that sequester carbon. At the same time, open space policies in developing and developed places, while adding marginally to sequestration, are effective strategies to adapt to climate change in places where the population is likely to grow.

With federal and state assistance, local governments can require or encourage owners of forested lands to enhance their sequestering landscapes. Localities can also shape land development patterns through land use regulations to reduce land coverage and impervious surfaces, limit flooding, retain and add vegetation, protect community character, and prevent ground and surface water pollution. In highly developed cities; tree canopies can be increased; green infrastructure added; urban gardens promoted; and buildings oriented to reduce the heat island effect. These strategies will make cities more attractive and lively places to live, and mute the effects of the higher densities needed near transit stations to attract new residents and workers, insuring that their carbon footprints will be lighter.