I have been inspecting the World Bank database, including development indicators based on FAO data. For some of these indicators, for instance "Permanent cropland (% of land area)" and "Land under cereal production," there is an abrupt dislocation in the time series between 1991 and 1992.

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This is not comparable to the year-to-year variability observed for the remaining years. I assume the dislocations are due to geopolitical events around the time, maybe incorporation of data from the former Soviet Union (the Russian Federation did not formally join the World Bank until 1992) or other states. However I can't tell whether the actual origin is changes in data because new regions or data sources were added or removed to the database, or because of problems on the ground with data reporting, acquisition, logging, sharing, etc, or due to actual changes in land use or production.

I checked the World Bank meta data but found it of little help:

The Food and Agriculture Organization (FAO) tries to impose standard definitions and reporting methods, but complete consistency across countries and over time is not possible. Thus, data on agricultural land in different climates may not be comparable. For example, permanent pastures are quite different in nature and intensity in African countries and dry Middle Eastern countries.
True comparability of the data is limited by variations in definitions, statistical methods, and quality of data. Countries use different definitions land use. The Food and Agriculture Organization of the United Nations (FAO), the primary compiler of the data, occasionally adjusts its definitions of land use categories and revises earlier data. Because the data reflect changes in reporting procedures as well as actual changes in land use, apparent trends should be interpreted cautiously.
Satellite images show land use that differs from that of ground-based measures in area under cultivation and type of land use. Moreover, land use data in some countries (India is an example) are based on reporting systems designed for collecting tax revenue. With land taxes no longer a major source of government revenue, the quality and coverage of land use data have declined.

Can someone shed light on the exact origin of these dislocations (for instance what sources might have been added or removed to the database, or whether acquisition or processing was done differently, in as much detail as possible)? Based on this I might have some options on modifying the data in such a manner as to minimize the dislocations and make trends clearer (recording of course a note that modifications were made).

  • $\begingroup$ @njuffa thanks for your comment. It is curious that a disruption in production in Europe (maybe not just Soviet Union of course) is supported by the per capita agricultural area, which shows a dip. However for Asia it does the opposite. Maybe demand driving increasing production there? See eg ourworldindata.org/grapher/agricultural-area-per-capita which is based on FAO data. $\endgroup$
    – Buck Thorn
    Commented Oct 19, 2023 at 17:03
  • $\begingroup$ @njuffa However I wonder if fallow fields would show up as a reduction in the reported agricultural area. Of course that would show up as a change in "permanent cropland". Thanks for your feedback. $\endgroup$
    – Buck Thorn
    Commented Oct 20, 2023 at 7:37


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