Smart Preservation News

Greenbelts Grow Local Climate Action

Rick Pruetz

Communities with greenbelts conserve more open space and consequently sequester more carbon than communities without greenbelts. Not surprisingly, greenbelts also help to concentrate urban growth, which reduces greenhouse gas (GHG) emissions associated with long commutes and promotes diverse, compact neighborhoods served by planet-friendly transportation systems and energy-efficient development. In addition to GHG mitigation, greenbelts that reduce development in forests, floodplains, coastal zones, and other hazard-prone areas also lower the risk of wildfires, floods, and sea level rise. Greenbelts generate a wealth of benefits but they are hard to adopt and maintain. However, some communities have succeeded by using a form of zoning that compensates the owners of permanently-preserved greenbelt land using private-sector incentives rather than tax revenues. 

Montgomery County’s greenbelt is essential to this county’s Climate Action Plan.

A 2021 study confirms the expectation that counties with greenbelts conserve more forests, farms, grasslands, wetlands, and other types of open space than surrounding counties without greenbelts (Han, Kim, and Daniels 2021). This study focuses on six US counties with a large amount of open space resulting from low density zoning, urban growth boundaries, and/or permanent preservation secured by perpetual easements or public ownership. The study acknowledges that zoning and urban growth boundaries can change over time. Consequently, some communities view greenbelts formed solely by zoning and/or urban growth as being reserved rather than preserved. More about that later.

The forests, farms, grasslands, and wetlands protected by greenbelts are capable of mitigating the GHG emissions responsible for climate change. The 2021 study used USGS factors for these four types of open space to estimate the capacity of each county’s carbon sink in terms of carbon stock and carbon flux, meaning the exchange of carbon between the atmosphere and the land. Again, not surprisingly, the counties with greenbelts outperformed their non-greenbelt neighbors. 

In addition to carbon sequestration, greenbelts can mitigate GHG emissions by helping to concentrate growth in higher density urban centers where per capita energy consumption is lower than in sprawling auto-dependent suburbs. The 2021 study declines to quantify this mitigation effect for various reasons including the difficulty of determining whether greenbelts are concentrating growth or encouraging growth to leapfrog into jurisdictions with more permissive land use regulations. However, a study by the International Resource Panel of the United Nations Environmental Programme concluded that compact urban form, by itself, can cut resource and energy use in half compared with the sprawl produced by business-as-usual land use practices. And when applied in an integrated, mutually-supportive manner with three other key factors, compact urban form can decrease resource use by 80 to 90 percent (IRP 2018).

In addition to mitigating GHG emissions by sequestration and compact urban form, communities can use greenbelts to adapt to climate change. By protecting open space, greenbelts reduce development in places vulnerable to climate-change-exacerbated hazards including wildfires, floods, and sea level rise while safeguarding biodiversity and protecting water sources threatened by development as well as the increased severity of heat, drought, and extreme weather events (Pruetz 2021).  

Montgomery County, Maryland has permanently preserved 72,000 acres in its 92,000- acre greenbelt, which it calls the Agricultural Reserve. Montgomery County turned to permanent preservation after decades of seeing land converted to development because it was only protected by zoning. Montgomery County’s 1980 plan for the Agricultural Reserve observed that owners of land in metropolitan areas experience “impermanence syndrome”, the resignation that occurs when farmers fear that neighboring property will ultimately be rezoned for residential subdivisions that make long-term agricultural activities difficult or impossible.

Permanent preservation is most commonly achieved when property owners record a conservation easement to reduce their tax obligations and/or to receive compensation through public programs funded by local taxes and/or grants from state and federal sources. In many communities, the voting public opposes being taxed for land preservation programs. Montgomery County as well as 282 other US communities use transfer of development rights, or TDR, a form of zoning in which developers of suitable places called receiving areas are allowed increased development potential when they compensate property owners who voluntarily preserve their land in places called sending areas. In the case of Montgomery County, sending site owners were granted one TDR for each five acres of land placed under permanent easement in the Agricultural Reserve and participating receiving area developers were allowed addition density by buying TDRs. Of the total 72,000 acres placed under easement in Montgomery County’s Agricultural Reserve, 52,000 acres were preserved by TDR. 

In its 2009 Climate Protection Plan, Montgomery County recognized the success of TDR in reducing GHG emissions and added that: “The Agricultural Reserve should continue to be protected for food production, recreation and carbon sequestration” (Montgomery County 2009, ES-9). 

In 2017, Montgomery County declared a climate emergency and committed to reducing GHG emissions by 80 percent by 2027 and 100 percent by 2035. In June 2021, the county unveiled a Climate Action Plan aimed at implementing ambitious goals using multiple strategies including ones that rely on the Agricultural Reserve. For example, Sequestration Action 4 – Regenerative Agriculture recommends increasing the Agricultural Reserve’s potential for improved carbon sequestration, biodiversity, water management, and natural ecosystems by increased regenerative agricultural practices incentivized by TDRs (Montgomery County 2021).     

Not all TDR programs have had the success experienced by Montgomery County. However, as detailed in Smart Climate Action through Transfer of Development Rights, TDR works for jurisdictions that observe proven factors when developing and adopting their TDR programs. As frustration grows over inadequate response to climate change at state and local levels, more local governments are likely to consider TDR as a way to create greenbelts and pursue other climate action strategies without relying entirely on tax revenues.     


Han, A., C., Kim, and T. Daniels: 2021. Managing urban growth in the wake of climate change: Revisiting greenbelt policy in the US. Land Use Policy. December 2021. Accessed 12-3-21 at

IRP (International Resource Panel). 2018. The Weight of Cities: Resource Requirements of Future Cities. Paris: United Nations Environmental Programme. 

Montgomery County. 2009. Climate Protection Plan. Accessed 12-4-21 at

Montgomery County. 2021. Climate Action Plan. Accessed 12-4-21 at

Pruetz, R. 2021. Smart Climate Action through Transfer of Development Rights. Arje Press. 

TDR without Borders:
An International Look at Transferable Development Rights  

January 13, 2014 

I just posted profiles of 37 TDR programs in 11 countries outside the United States to making them freely available at the “TDR Updates” tab. I found these programs while writing an article published in Built Environment (Volume 39, Number 4, 2013) entitled Transfer of Development Credits Helps Cities Grow Up. That article argues that TDR can be a relevant and useful tool outside as well as inside the US when jurisdictions follow the 10 rules shown to produce successful TDR programs.

Australia (6) Brisbane, Gosford, Ipswich, Melbourne, Perth, Sydney
Brazil (1) Porto Alegre
Canada (2) Toronto, Vancouver
France (7) La Cadiere d’Azur, La Clusaz, Les Gets, Le Grand Bornand,
Longeville Sur Mer, Lourmarin, Taninges
India (1) Mumbai
Italy (14) Casalecchio di Reno, Cesena, Cremona, La Spezia, Monza, Padua,
Parma, Piacenza, Regio Emilia, Ravenna, Rome, Schio, Turin, Venice
Japan (1) Tokyo
Mexico (1) Sian Ka’an
Netherlands (1) Brabant
New Zealand (1) Auckland
Puerto Rico (1) San Juan
Spain (1) Almeria

I was pleased to learn about TDR experiences in other countries. But 37 programs represents less than 12 percent of the 320 TDR programs that I have been able to find so far. The other 283 TDR programs are from US jurisdictions. Of this US subtotal, 242 are profiled and freely accessible at while case studies of the other 41 US programs can be found in The TDR Handbook (Island Press, 2012).

As explored in my Built Environment article, underwhelming foreign use of TDR may suggest that planners in other countries are not convinced that TDR is an effective planning implementation tool. In response, I argue in Built Environment that many TDR programs don’t work because they don’t observe the success factors identified in the study that Noah Standridge and I published in the Winter 2009 issue of the Journal of the America Planning Association: “What Makes Transfer of Development Rights Work? Success Factors from Research and Practice.”

Some foreign planners may also question the relevance of TDR outside of the US because of misconceptions about the purpose of TDR. As discussed my Built Environment article, planning literature has repeatedly portrayed TDR primarily as a legal defense against a claim based on the Fifth Amendment of the US Constitution that a regulation has gone so far that it has effectively “taken” private property for public purposes without compensation. In reality, US jurisdictions should not rely on TDR as their sole defense against a taking challenge since the US Supreme Court has not yet definitively ruled on how much legal cover TDR would provide in the event that a regulatory taking has actually occurred.

Despite the fact that TDR is not primarily a legal strategy, the impression persists in many circles that TDR is chiefly designed as a means of complying with property rights protections in the US Constitution. Unfortunately this may have led many foreign practitioners to assume that TDR is inapplicable in countries where compensation has traditionally been required only when a regulation has led to the revocation of building permits or actual damage to private property.

As planners who have followed TDR closely know, very few US TDR programs involve regulations that would constitute a taking within the criteria established by the 1992 US Supreme Court decision of Lucas v South Carolina Coastal Council: a regulation that eliminates all economic use of a property unless the use would have been prohibited by the state’s underlying property and nuisance law. In fact, most US TDR programs are not adopted in conjunction with any form of downzoning, (a zoning change that reduces development potential.) Yet, many planners in other countries continue to dismiss TDR as a solution to a uniquely US problem.

In most US programs, TDR allows developers to voluntarily achieve additional development potential in an appropriate location when they contribute to community benefits established in the TDR ordinance. Some US jurisdictions use TDR to create affordable housing or public facilities but most programs aim to preserve environmental areas, farmland and historic landmarks. At home and abroad, planners rely primarily and sometime exclusively on zoning to achieve their land use goals despite evidence that these tools do not adequately protect significant natural and agricultural areas. In a 1997 survey, US planners confirmed their preference for zoning even though less than one third of the respondents expected that they would actually achieve all of their preservation goals with their current regulations and level of conservation funding. The inadequacy of zoning is perhaps best illustrated by the sad statistic that between 1982 and 2007, the population of the contiguous US grew by 30 percent while the amount of land converted to development in this time period grew 56 percent, almost twice as much.

Zoning alone is not winning the war on sprawl. The limits of regulation are perhaps best illustrated by impermanence syndrome, a state of mind afflicting the owners of farmland in US peri-urban areas. These owners fear that nearby land will be rezoned for urban or suburban development, creating land use conflicts that make the continuation of agriculture difficult or impossible. The perceived inevitability of urban encroachment often prompts these landowners to defer agricultural investments and land stewardship, causing further decline of rural activities and lifestyles, ironically accelerating sprawl. As illustrated in my 2012 book, Lasting Value, permanent preservation can treat and perhaps cure impermanence syndrome. As perpetual conservation easements are recorded in peri-urban areas, neighboring landowners gain confidence in the future of rural pursuits and often preserve their land as well. The maps of conservation easements in places like Lancaster County, Pennsylvania and Montgomery County, Maryland demonstrate how permanent preservation can spread through a community and stop sprawl in its tracks.

As with perceptions about the relevance of TDR, planners in other countries may also believe (or perhaps want to believe) that sprawl is a US problem. So called command-and-control land use systems in other countries rely primarily on regulations to keep unwanted growth out of important farmland and natural areas. Command and control seems to work, to an extent, partly because jurisdictional organization in other countries appears to be more rational than the balkanization and cross-border rivalry that characterize most US metro areas. But, while regulations might be more effective abroad than in the US, they don’t always produce perfection. Private property owners around the world apply pressure to develop their land and sometimes elected officials respond to that pressure. In other words, perhaps other countries may not need permanent preservation as much as the US, but many need to do more than simply rely completely on regulatory control.

The 37 international TDR programs just added to demonstrate an understanding that TDR is relevant beyond the US and that it can be a useful tool for permanently securing land use goals without reliance on taxes. As an advocate of TDR, I hope to see expanded international use. But I also recognize the need to be sensitive to each country’s land use laws and customs. Some countries might want to avoid a TDR program that provides compensation for permanently limiting the amount of development allowed on private land. However, as shown by the profiles of some TDR programs in Italy, Spain, and Gosford, Australia, TDR can also be used to acquire land in fee for parks, greenbelts and public facilities. Conversely, other countries might view TDR as simply a means of recapturing part of the value of bonus development potential and redirecting it to community benefits ranging from affordable housing, parkland and civic buildings to permanent development restrictions on private land. Of course, to deliver these outcomes, TDR programs must actually work. To do that, jurisdictions at home and abroad must build programs with the factors found in the 20 most successful US programs as detailed in our Winter 2009 JAPA article.

Beaufort TDR Program Wins Award