Wednesday, January 10, 2018
Low Carbon Land Use: Paris, Pittsburgh, and the IPCC: Post 3: Carbon Emissions: The Land Use Connection: A Series by John R. Nolon
[This post is the third in a series that will appear over the coming months.]
Low Carbon Land Use: Paris, Pittsburgh, and the IPCC.
Carbon Emissions: The Land Use Connection
by John R. Nolon Distinguished Professor of Law
Elisabeth Haub School of Law at Pace University
Local land use law can permit McMansions: super-large homes that consume outsized quantities of fossil fuel for heating and cooling. The law that causes the resulting emissions can be changed. Larger houses can be required to be more fuel efficient and home sizes can be capped. In Marin County, California, for example, a land use regulation requires that the larger the house, the more energy efficient it must be. Houses exceeding 6,500 square feet must be net zero energy users. What architects and engineers can do, the law can embrace. This modest example focuses on the critical fact that residential and commercial buildings contribute nearly 40% of national CO2 emissions.
Alternatively, houses can simply be required to be smaller: to have less space to heat and cool. In Petaluma, California, where zoning initially favored single-family construction, the City rebalanced the future housing stock by adopting the Petaluma Plan to accommodate sudden growth pressures in the 1970s. The plan -- and zoning that implemented it -- limited growth to 500 dwelling units per year. Using an intricate point system, it rewarded builders who proposed projects that conformed to the plan and its environmental design standards. The land use regulations required that housing be evenly divided between single-family and multi-family dwelling units, a consequence of which was less energy consumption and fewer emissions per-capita.
The per capita result is critical. The population of the U.S. is growing and that growth is significant. It matters where and how people live. According to the 2015 New York City Inventory of Greenhouse Gases, the average City dweller emits 6.1 metric tons annually. In Bedford, a sprawling suburb of the City, the average is 25 per capita; in the northern Atlanta suburbs it bulges to 35. Nationally, the per capita average emission metric is 24.5 tons.
Similarly, land use regulations can reduce vehicle miles travelled. The movement of personal vehicles through the built environment contributes over 20% of CO2 nationally. Cars travel to convey their occupants from where they live to where they work, play, shop, and learn. The more distance between these destinations, the more miles travelled and the more emissions. By creating mixed-use, higher density zones around transit stations, local governments can significantly lower carbon emissions. When density is increased for both residential and commercial uses, the distance between origin and destination is shorter, and walking, bicycling, and mass transit services are more feasible. Studies have shown that mixed-use zoning and increased population density decrease automobile ownership and the number of vehicle miles travelled.
Centering growth has a corollary benefit. It focuses needed development on urban places and moves it away from more remote open spaces. In those places, ecological services on which life and prosperity depend are preserved as a consequence. One of those services is the biological sequestration of CO2. Up to 15% of CO2 is sequestered by the natural environment, more if that sequestered by undisturbed soils is counted.
As sprawling development consumed increasing amounts of open lands during the last quarter of the 20th century and into the 21st, local land use law responded. Its tool box is now full of sequestration-enhancing implements: clustering development, planned unit ordinances, and neighborhood tree canopy enhancement standards, for example. Sustainable neighborhood design standards include green roofs, rain gardens, vegetated swales, xeriscaped lawns, biologically-rich site design, and connected green landscapes. All of these land use laws protect and enhance the biologically sequestering environment and reduce the climate changing emissions from all sources.
The connections between land use law and emissions are demand-side strategies. They either reduce the demand for fossil fuels by lowering energy use in buildings and the emissions attributable to vehicle miles travelled, or they capture the resulting emissions through the natural environment. All told, these strategies address over 70% of emissions.
These strategies operate in different policy sphere from more traditional GHG mitigation initiatives such as a carbon tax, cap and trade mechanisms, or clean power regulations affecting coal-fired generation. At the national level, these supply-centered strategies are mostly on hold for the duration of the current administration. The opposite is true of strategies employing land use tools on the demand-side. As demonstrated in the previous post, the Paris Accord embraced these strategies as valued Nationally Determined Contributions to mitigation.
As this story plays out in the U.S., other countries, still committed to top-down, supply- side strategies, can benefit by embracing such grassroots efforts. This combination provides hope that the Paris Accord can effectively counter the worsening evidence of climate change.
Material from this series will appear in Low Carbon Land Use: Paris, Pittsburgh, and the IPCC, an article to be published by the Arkansas Law Review.
Previous posts in this series are available here:
Post 1: Paris, Pittsburgh, and the IPCC
Post 2: Post-Paris Contagion