James Gerber

University of Minnesota Twin Cities | UMN · Consortium on Law and Values in Health, Environment & the Life Sciences

Accurate predictions of crop yield are critical for developing effective agricultural and food policies at the regional and global scales. We evaluated a machine-learning method, Random Forests (RF), for its ability to predict crop yield responses to climate and biophysical variables at global and regional scales in wheat, maize, and potato in comp...

With increasing nitrogen (N) application to croplands required to support growing food demand, mitigating N2 O emissions from agricultural soils is a global challenge. National greenhouse gas emissions accounting typically estimates N2 O emissions at the country scale by aggregating all crops, under the assumption that N2 O emissions are linearly r...

Soils play a pivotal role in major global biogeochemical cycles (carbon, nutrient and water), while hosting the largest diversity of organisms on land. Because of this, soils deliver fundamental ecosystem services, and management to change a soil process in support of one ecosystem service can either provide co-benefits to other services or can res...

Carbon stock estimates based on land cover type are critical for informing climate change assessment and landscape management, but field and theoretical evidence indicates that forest fragmentation reduces the amount of carbon stored at forest edges. Here, using remotely sensed pantropical biomass and land cover data sets, we estimate that biomass...

A growing and more affluent human population is expected to increase the demand for resources and to accelerate habitat modification, but by how much and where remains unknown. Here we project and aggregate global spatial patterns of expected urban and agricultural expansion, conventional and unconventional oil and gas, coal, solar, wind, bio-fuels...

Agricultural trade plays an important role in global food security and resource sustainability. Global food commodities trade is worth more than US$520 billion per year, could feed approximately two billion people, uses about 13% of worldwide cropland and pasture, and has geographically concentrated irrigation water demands. However, researchers ra...

Many studies have examined the role of mean climate change in agriculture, but an understanding of the influence of inter-annual climate variations on crop yields in different regions remains elusive. We use detailed crop statistics time series for similar to 13,500 political units to examine how recent climate variability led to variations in maiz...

Pollinators contribute around 10% of the economic value of crop production globally, but the contribution of these pollinators to human nutrition is potentially much higher. Crops vary in the degree to which they benefit from pollinators, and many of the most pollinator-dependent crops are also among the richest in micronutrients essential to human...

Achieving sustainable global food security is one of humanity’s contemporary challenges. Here we present an analysis identifying key “global leverage points” that offer the best opportunities to improve both global food security and environmental sustainability. We find that a relatively small set of places and actions could provide enough new calo...

Yield gap and increasing production calculations Yield gaps were calculated based on methods defined in previous studies (3, 13, 32), which groups spatially-explicit yield data in Monfreda (30) in 100 equal-area climate "bins." Bins are crop-specific and are defined based on annual precipitation and growing-degree days. Climate data were from World...

Nitrogen fertilizer use across the world's croplands enables high-yielding agricultural production, but does so at considerable environmental cost. Imbalances between nitrogen applied and nitrogen used by crops contributes to excess nitrogen in the environment, with negative consequences for water quality, air quality, and climate change. Here we u...

Background/Question/Methods Assessments of changes in ecosystems need to account for the ability of ecosystems to supply and deliver services to societies but also on tradeoffs and synergies among services. Yet, little is known about how services are related to each other and which services can be delivered in the same spatial areas. Metrics that...

Background/Question/Methods Growth in agricultural trade has important implications for management of global land and water resources. Exports of agricultural commodities embody the characteristics of the production systems they are derived from among different regions. If countries import specific commodities rather than producing them domestical...

Background/Question/Methods Global demand for energy and minerals has increased by 25-50 percent over the last half-century, and a similar increase is projected by 2030. Development to meet these growing demands has resulted in impacts to human health and well-being as well as increased habitat loss and modification and further stress on biologic...

Worldwide demand for crops is increasing rapidly due to global population growth, increased biofuel production, and changing dietary preferences. Meeting these growing demands will be a substantial challenge that will tax the capability of our food system and prompt calls to dramatically boost global crop production. However, to increase food avail...

Yield gap analysis, which evaluates magnitude and variability of difference between crop yield potential (Yp) or water limited yield potential (Yw) and actual farm yields, provides a measure of untapped food production capacity. Reliable location-specific estimates of yield gaps, either derived from research plots or simulation models, are availabl...

We evaluate the comparative productivity of maize and sugarcane biofuel feedstocks as a function of latitude. Solar radiation for photosynthesis varies by latitude and contributes to differential productivity of tropical and temperate zones. We calculate comparative productivity in two ways—the amount of net sugar energy produced per unit area, and...

In the coming decades, a crucial challenge for humanity will be meeting future food demands without undermining further the integrity of the Earth's environmental systems. Agricultural systems are already major forces of global environmental degradation, but population growth and increasing consumption of calorie- and meat-intensive diets are expec...

Background/Question/Methods Agricultural expansion (both in the form of cropland and pastureland) is a persistent pressure on Amazonia’s tropical forest resources, with that land-use change having associated environmental impacts on one of the world’s most biodiverse and carbon-rich tracts of tropical forest. As population size and incomes increa...

What will happen to global crop production under climate change scenarios if the footprint of agriculture is frozen? Research based on empirical crop yield models has shown that if the crop mix is unchanged, global production decreases under climate change. Here, with a focus on cereal production, we allow the mix of crops (but not the cropland) to...

Over two billion people worldwide suffer from inadequate levels of micronutrients, mainly in the form of iodine, iron, and vitamin A deficiencies. With a growing population, producing crops that contain high amounts of these micronutrients is of increased importance. Addressing these deficiencies sustainably requires a detailed examination of the a...

Agricultural land occupies approximately 4.9 billion hectares of the earth's surface. The amount of land that is required to feed a person differs globally, however, dependent mainly on diet. Diets dense in grain-fed animal protein require more land than plant-based diets in order to supply the same quantity of calories and protein. As the world's...

Meeting the expected doubling of food demand by 2050 will require either expansion of the world's croplands into sensitive ecosystems or the intensification of production on existing croplands. Although both strategies involve environmental tradeoffs, more sustainable pathways of cropland intensification (which minimize local environmental external...

The Amazon is not only an exceptionally biodiverse and carbon-rich tract of tropical forest, it is also a case study in land use change. Over the next forty years it will continue to experience pressure from an urbanizing and increasingly affluent populace: under a business-as-usual scenario, global cropland, pasture and biofuels systems will carry...

Increasing population and consumption are placing unprecedented demands on agriculture and natural resources. Today, approximately a billion people are chronically malnourished while our agricultural systems are concurrently degrading land, water, biodiversity and climate on a global scale. To meet the world's future food security and sustainabilit...

This paper presents two sets of quantitative predictions for global soy and maize yields under changes to temperature and precipitation. The climatic changes considered are based on IPCC scenarios A1B and B1 as calculated with a variety of GCMs. One set of crop yield predictions is calculated with the process-based PEGASUS model, the other is based...

The continued expansion and intensification of agriculture are key drivers of global environmental change. Meeting a doubling of food demand in the next half-century will further induce environmental change, requiring either large cropland expansion into carbon- and biodiversity-rich tropical forests or increasing yields on existing croplands. Clos...

Agricultural land-use, which now covers one-third of earth's ice-free surface, is a dominant driver of global environmental change. With an increasing population and rapidly changing diets, there's much discussion over how to increase the productivity of existing croplands. Agricultural productivity is usually defined in terms of yield: tons of a g...

Various countries have mandated ethanol blending into transportation fuel and increase in biodiesel production over time. To grow the extra biofuel either an intensification to prevent further land cover changes or extensification that would result in land cover change would be imperative. In this paper we developed and applied the relationship bet...

Optimizing pastureland use has the potential to be a key part of sustainably meeting the growing global demands for food, feed, fiber, and fuel. This study identified where and to what degree we can utilize pastureland more intensively. We quantified and mapped the pasture utilization intensity, which is the ratio of current to potential pasturelan...

Intensity correlations for ocean acoustic propagation show markedly different behavior in the partially saturated regime than in the fully saturated regime. In contrast to the known exponential decay of temporal intensity correlations in full saturation, partial saturation correlations fall off very slowly. This phenomenon is a consequence of the p...