Abstract Improved access to data on land prices is vital for future advances in global change science and policy. Spatially explicit land price information should be a public good available to the international community. An open-access, global land price database would enable policymakers, scientists, and civic society to better grapple with the economic, social, and environmental challenges posed by global change. As multiple land uses compete for a decreasing reserve of available land, understanding the processes and outcomes of land-use decisions is critical to global sustainability (Lambin and Meyfroidt 2011). Land prices are a major driver of land-use dynamics, being a key factor in land acquisition and land-use decisions, a reflection of expected returns to land-based economic activity, and a signal of scarcity. However, despite their importance for understanding economic, social, and environmental outcomes of land use, land prices are often “proxied” by coarse measures such as market accessibility or, more often, omitted entirely from analyses because of lack of data. Land price information should be a public good, with new initiatives aimed at overcoming gaps in our understanding of the determinants and outcomes of land prices worldwide. Efforts toward an open-access global land price database will require innovative partnerships between public and private sectors to ensure transparency and access. A commitment to providing accessible land price data will enable policymakers, scientists, and civic society to better grapple with a wide range of contemporary issues, from economic growth and inequality to urban development and rural land-use policy, nature conservation, and sustainability. Land value and prices Land is the most important mainstream global financial asset, exceeding the worth of all equities, securities, and gold combined. In a 2016 study, Savills (a United Kingdom–based, international property services company) estimated the value of world developed real estate at $217 trillion, or three times global annual GDP and contributing 60% of global financial assets. For the United States, Larson (2015) determined the value of all land at $23 trillion, of which about 24% by area and 8% by value are held by the federal government. Because land is both an asset and a key factor of production, its price influences a range of production decisions and investment choices, as well as productivity and profits, ultimately shaping global trade, urban development, economic growth, and the distribution of wealth. Price signals strongly influence important land-use transitions such as the conversion of farmland into housing development on the urban fringe, deforestation of tropical rainforests for commodity crops and cattle, and large-scale farmland acquisition in developing countries. In addition, the opportunity cost of land shapes land allocation for protected areas as well as the valuation of ecosystem services and biodiversity, both directly by setting financial incentives for land managers and indirectly through land-use or land-cover change. Despite the pivotal role of land values, a critical gap persists in the availability, accessibility, and resolution of georeferenced data on the price of land around the world. A global database Over the past two decades, the development of novel spatially explicit data sets has enabled scientists to analyze the nature, pace, and drivers of global change. The public release of Landsat satellite imagery by the US Geological Survey, in parallel with advances in cloud computing and collaborative processing within Google's Earth Engine platform, for example, allowed researchers at the University of Maryland to map global forest-cover change for the first time at high spatial and temporal resolutions. Similar efforts are providing new data to guide research, modeling, and policy on global land use and landscape management (Erb et al. 2017). Although our ability to monitor and detect global biophysical changes still far exceeds that for social and economic conditions, a growing number of initiatives seek to produce global spatial data on socioeconomic variables, including population (Gridded Population of the World, WorldPop), infrastructure (Global Roads Inventory Project), land tenure and protection status (LandMark, Protected Planet), and economic development (Night Lights Development Index). A similar initiative is needed for global land prices. Not surprisingly, more data are available for high-value commercial and residential land in urban areas, such as London or Tokyo, and urbanized OECD countries, than for rural areas and developing countries (figure 1). Even in industrialized countries, researchers often focus either on urban or rural (farmland) prices and overlook where the two land markets meet: at the site of urban sprawl on the fringe of cities. Land price data are gathered and held by a disparate array of government sources (e.g., tax assessment agencies, land registries, federal and state agriculture agencies, central banks) and statistical services (e.g., OECD and EuroStat). Commercial firms specialize in real estate or agribusiness intelligence, such as CoStar Group, Savills, Frank Knight, Canada MLS, and Informa. And a myriad of research institutes, foundations, and professional societies (e.g., Wharton Business School, Lincoln Institute of Land Policy, and Royal Institute of Chartered Surveyors) compile and present land price data at different scales. In their study of house prices in 14 advanced economies since 1870, for example, Knoll and colleagues (2017) drew on 60 distinct data sources. Indeed, research efforts are multiplying toward assembling national and supranational land price estimates, both historical and current (e.g., Jadevicius et al. 2015, Knoll et al. 2017), to design innovative ways of estimating the value of land, and to fuse price data with geospatial information systems (Spinney et al. 2010, Larson 2015). Figure 1. View largeDownload slide A conceptual diagram of variation in land prices, their public availability, and potential data sources along stylized land-use gradients. Data availability typically follows the price of land, with high-resolution data available for urban areas and coarse resolution or often no data available for land that is not under commercial, residential, or agricultural use. Critical areas where land price data are lacking include rapidly urbanizing regions and remote agricultural frontiers. Dynamics at different scales and in different locales can influence each other through globalization (depicted by arrows on the right of the figure). Figure 1. View largeDownload slide A conceptual diagram of variation in land prices, their public availability, and potential data sources along stylized land-use gradients. Data availability typically follows the price of land, with high-resolution data available for urban areas and coarse resolution or often no data available for land that is not under commercial, residential, or agricultural use. Critical areas where land price data are lacking include rapidly urbanizing regions and remote agricultural frontiers. Dynamics at different scales and in different locales can influence each other through globalization (depicted by arrows on the right of the figure). The challenges An initiative to create a transparent, open-access, and impartial global land price database would be potentially disruptive. Governments have an uneven record for retaining and releasing land price data, such as the United Kingdom's Valuation Office Agency (VOA) decision in 2011 to cease to collect and publish its land price indices or even to use land price data themselves (Cheshire and Sheppard 2005). Sweden is an exception, with its recent development through a public–private partnership including Lantmäteriet, ChromeWay, and Kairos Future of a new land registry system based on blockchain technology, emerging as a leader in this area by advising other countries on this new technology. Firms specializing in agribusiness intelligence and real estate clearly prefer to restrict access to information so as to preserve rents and commercial advantage through asymmetric information and arbitrage. The uneven public availability of land assessment records across jurisdictions and countries also reflects reluctance among some landowners to reveal price information. Overcoming political–economic resistance would yield multifarious benefits, most immediately in enhanced land market efficiency and land allocation policies. There are several technical hurdles to creating a global land price database. To provide the foundations for a global database, a permanent public data repository intended explicitly for the storage of land price data is needed. This repository could be populated with existing high-resolution data, currently available only in select countries, and compiled into a common structure. Such data would be built on and “scaled up” through international collaborations to fill gaps in coverage globally. In developing a common structure, researchers will have to grapple with thorny issues related to the choice of price measures and estimation methods, as well as the spatial and temporal resolution of data. Where recorded land prices are not available, researchers can estimate land values indirectly using hedonic pricing methods (i.e., where land prices are assumed to reflect nearby house prices and environmental amenities), spatial transaction approaches, and decomposition (“residual”) analysis (Larson 2015). Practically, price data will likely comprise both measured values and estimations, given the low turnover in land sales, the common conflation of land value with property improvements (e.g., housing or irrigation), the uncertainty associated with land speculation, and the uneven availability and quality of data from land sales, listings, and appraisals. Price data available at scales ranging from individual parcels and properties to municipalities and counties would need to be reconciled and georeferenced so that the data can be spatially matched with information on related land use and land tenure. Land price data collected at disparate time resolutions (some with a single observation, others with varying degrees of frequency, from months to decades) will need to be unified into a common time frame, implying choices about aggregation and interpolation. A concerted effort is required to ensure consistency and comparability across sites to develop a spatially resolved, long-term time series of land prices. Applications Despite many open questions, the technical and political–economic challenges posed are not insurmountable. Technical advances in georeferencing, data processing and archiving, remote sensing and GIS, and communications have significantly reduced the cost of building databases and enabled data cleaning and harmonization. Similar challenges are being tackled, for example, in the production of global, fine-resolution population (e.g., WorldPop, www.worldpop.org.uk) and land cover and cropland data (e.g., the Food and Agriculture Organization of the United Nations’ Global Agro-Ecological Zones, FAO GAEZ). Data-mining methods can now be used to relatively efficiently and quickly compile and assemble data published online. Crowdsourcing has been successfully used to gather spatial data—such as with OpenStreetMap, the Logging Roads project, or the Land Matrix database—and may offer new opportunities for the verification of reported land price data. Innovations in data visualization now make possible interactive map designs of property values through the fusion of spatial data. In the near future, blockchain technology and smart contracts will enable more efficient tracking of verified land transactions without the need to rely on intermediaries. Still, regardless of the considerable promise of blockchain technology, the issue of data access for science and society is likely to remain. A commitment to sharing land price information and the release of a global database would provide new opportunities for innovation and enable fresh breakthroughs for research across multiple scientific fields. Global land price data would advance our understanding of the dynamics of urban sprawl, the functioning of land markets, land speculation and rural land grabbing, frontier deforestation and the forest transition, and trajectories of land system change. Enhanced land price information would foster research aimed at understanding the dynamics of rising income and asset inequality around the world, the drivers of economic growth, and the impacts of global trade. Furthermore, such data would enable a deeper understanding of the role of landholding in individual wealth accumulation, as well as a social determinant of health, subjective well-being, and mobility. Land price data would also enable advances in areas at the core of sustainability science, including the valuation of ecosystem services, the assessment the tradeoffs and synergies in raising agricultural productivity, and the foundations of food security. In conservation science, land price information would helpfully inform research aimed at valuing and protecting critical wildlife habitat, from urban marshlands to tropical rain forests, and preserving biological diversity. Finally, beyond the realm of science, access to comprehensive land price data will benefit the policy community as well as all those in civic society, nongovernmental organizations, businesses, governments, and international agencies who are engaged with complex and pressing land-related issues around the world. Given the transformative potential for both science and policy, the time is ripe for land prices to be considered as an informational public good and for the global community to work toward the creation of a unified global land price database. References cited Cheshire PC , Sheppard SC . 2005 . The introduction of price signals into land use planning decision-making: A proposal . Urban Studies 42 : 647 – 663 . Google Scholar CrossRef Search ADS Erb K‐H et al. 2017 Land management: Data availability and process understanding for global change studies . Global Change Biology 23 : 512 – 533 Google Scholar CrossRef Search ADS PubMed Jadevicius A , Huston D , Baum A . 2015 . Two Centuries of Farmland Prices in England . Saïd Business School, Oxford University . Working Paper no. RP 2015–8 . Knoll K , Schularick M , Steger T . 2017 . No price like home: Global house prices, 1870–2012 . American Economic Review 107 : 331 – 353 . Google Scholar CrossRef Search ADS Lambin EF , Meyfroidt P . 2011 . Global land use change, economic globalization, and the looming land scarcity . Proceedings of the National Academy of Sciences 108 : 3465 – 3472 . Google Scholar CrossRef Search ADS Larson W. 2015 . New Estimates of Value of Land of the United States . Bureau of Economic Analysis, Office of the Chief Statistician . Spinney JEL , Kanaroglou PS , Millward HA . 2010 . Improving access to land price data: A spatial decision support system for cleansing land registry data . Canadian Journal of Research Science 33 : 57 – 72 . © The Author(s) 2018. Published by Oxford University Press on behalf of the American Institute of Biological Sciences. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)
BioScience – Oxford University Press
Published: May 30, 2018
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