In Creating a Sustainable Food Future: Interim Findings, we proposed that the world needs to find ways to sufficiently feed itself without any further conversion of natural ecosystems into crops. We found, however, that it may be difficult to boost crop yields and limit crop demand growth sufficiently to close the approximately 70 percent gap between global crop calories available in 2006 and those needed in 2050 with absolutely no expansion of cropland.

New cropland historically has come from the conversion of forests, grasslands and wetlands. But such conversion generally has high environmental and social impacts. Finding alternative locations for any inevitable cropland expansion is therefore urgent.

In a new working paper, we argue that ensuring cropland expansion through mid-century and beyond is limited to “lands with low environmental opportunity costs” is the route most consistent with a sustainable food future.

Avoiding Ambiguity

One oft-cited, acceptable location for cropland expansion is degraded lands. But this solution is not as straightforward as it might seem in light of several challenges, including:

  • There is little consensus on the definition of “degraded land.” While some researchers focus on soil degradation, others focus on lands that have lost natural vegetation or even croplands that are not meeting potential yields.
  • Estimates of degraded land extent and location vary widely and often do not overlap.
  • Much of the land typically characterized as degraded is already cropland. By definition, it cannot be a candidate for cropland expansion, but rather for restoring crop productivity (which we support).
  • Although the phrase might connote vast tracts of uninhabited or unutilized land, degraded lands are not necessarily vacant areas that are unused by people or that fail to provide benefits.
  • There appears to be a “race for degraded lands” among a variety of interests, including those seeking to boost food production, increase wood product supplies, advance bioenergy, and restore native ecosystems. Thus, there is an emerging competition for these lands.

Beyond invoking “degradation,” other attempts to identify areas suitable for crop expansion often point to lands whose conversion actually would have high environmental impacts or forgone benefits. These lands include: (1) “potentially arable” land that is not currently farmed, (2) wet savannas, (3) grazing lands, (4) secondary forests, and (5) abandoned farmland. Considering these land types as always or inherently appropriate for cropland expansion can lead to overestimates of the amount of land available for sustainable cropland expansion, creating unrealistic expectations.

Identifying Lands with the Lowest Environmental Opportunity Costs

To accommodate any cropland expansion in a manner consistent with a sustainable food future, we need to circumvent these challenges. One approach is to limit any expansion of cropland to lands with low environmental opportunity costs. This concept acknowledges that there are typically opportunity costs to expanding crops onto a tract of land—the opportunity to use that land for some other purpose, or to merely let it regenerate into something eventually approaching its native ecosystem. Although borrowed from the world of economics, “opportunity costs” in this context focuses on forgone environmental benefits.

We propose that lands with low environmental opportunity costs are those that simultaneously meet at least four criteria:

1) Not already supporting crops: Land that is already being used for crop production (no matter how unproductive) is not eligible for cropland area expansion.

2) Minimal impact on native ecosystems and biodiversity: Any cropland expansion should avoid converting natural ecosystems or negatively impacting wildlife.

3) Low “carbon loss to crop production” ratios: These are lands whose conversion to cropping would release relatively little carbon compared to the likely tons of crop production per hectare.

4) Low “blue water” footprint: These are lands whose conversion to cropping would lower or at least maintain pressure on freshwater resources.

The extent of lands with low environmental opportunity costs is uncertain. We have not yet conducted a global mapping analysis.

Tracts of land that do meet these four criteria should then be assessed against a set of non-biophysical considerations that determine whether the tract should or even could be converted into cropland. These considerations include:

5) Economic viability: Is converting the tract of land into cropland affordable for the farmer?

6) Legal availability: In light of land-use zoning and other policies, is it legally possible to convert the tract of land to cropland?

7) Social acceptability: Do the people living on or holding rights to the tract of land want it converted to cropland?

8) Best alternative use: Is cropping an optimal use of that tract of land relative to alternatives, such as letting the native ecosystem recover?

Failure to meet criteria five, six, and seven does not mean that a tract of land should necessarily be removed from consideration since steps could be taken to improve performance against those criteria. For example, introducing economic incentives could improve economic viability.

Limiting Cropland Expansion to Only These Lands

To ensure that any future cropland expansion is limited to lands with low environmental opportunity costs, three sets of measures are needed. The first set is designed to generate a clearer understanding of what and where lands with low environmental opportunity costs are located, including:

  • Agreeing on a clear definition;
  • Applying our criteria to generate maps; and
  • Identifying cleared or abandoned agricultural lands where biophysical or human factors are blocking natural regeneration.

The second set would facilitate use of lands with low environmental opportunity costs, including:

  • Prioritizing lands with low environmental opportunity costs in participatory spatial planning;
  • Clarifying and strengthening land tenure on lands with low environmental opportunity costs;
  • Introducing financial incentives such as tax breaks for farmers to use lands with low environmental opportunity costs;
  • Improving technical assistance and rural extension for using such lands; and
  • Strengthening community engagement processes.

The third set discourages cropland expansion to lands with high environmental opportunity costs by making the financial, reputational, market access, or legal “cost” of converting natural ecosystems into cropland greater than the cost of expanding onto lands with low environmental opportunity costs. These include:

  • Introducing and enforcing moratoriums on converting natural ecosystems;
  • Accelerating adoption of “deforestation-free” supply chain commitments; and
  • Implementing monitoring systems.

Combined, these measures can contribute to the menu for a sustainable food future.