The Mississippi River Basin (MRB)-one of the most important agricultural regions in the world-faces significant water sustainability challenges due to intensive farming practices and excessive fertilizer use. In addition to efforts to encourage the adoption of more efficient and sustainable on-farm practices, several government programs have been developed with a focus on land conservation to reduce impacts on freshwater resources. Chief among these is the Conservation Reserve Program (CRP), which provides financial incentives for rural landowners to convert environmentally sensitive land into ecologically beneficial land cover. Over its four-decade history, the CRP has shown promising results in reducing soil erosion and improving water quality and wildlife habitat. However, recent surges in crop demand and agricultural commodity prices have led to higher land rental rates, increasing the need to ensure that finite CRP rental payments are allocated efficiently to maximize the program's ecosystem benefits. We employ a dynamic panel regression model with two-way fixed effects to assess the responsiveness of CRP enrollment to variations in county-level rental payments and apply a spatial linear optimization framework to reallocate CRP rental payments across counties with the goal of minimizing total MRB-wide nitrogen surplus. Our results indicate that optimized CRP enrollment strategies could increase nitrogen surplus reduction in the MRB by about 8% with up to a 50% adjustment in state-level rental payments and no increase in the basin-wide budget. The reduction rises to as much as 24% when the same rental flexibility is paired with a 30% increase in the total CRP budget. These changes correspond to an annual reduction of approximately 0.17-0.55 million metric tons of avoided nitrogen surplus compared with current levels. Although these reductions do not directly imply proportional decreases in riverine nitrogen loads, they represent 2%-35% of the nitrogen load currently reaching the Mississippi Delta. These findings underscore the promise of spatially optimizing and increasing CRP rental payments and highlight the program's significant potential for enhancing water sustainability throughout the MRB. Our study also presents a transferable framework for optimizing the allocation of limited conservation funding across agricultural landscapes facing similar challenges.

Climate change threatens smallholder agriculture and food security in the Global South. While cropland expansion is often used to counter adverse climate effects despite ecological trade-offs, the benefits for diets and nutrition remain unclear. This study quantitatively examines relationships between climate anomalies, forest loss from cropland expansion, and dietary outcomes in Nigeria, Africa’s most populous country. Combining high-resolution data on forest cover and climate variables within random forest and panel regression models, we find that 25 to 31% of annual forest loss is linked to climate variability. Using georeferenced household survey data, we then find that changes in forest cover have a significant positive association with changes in child diet diversity—a key proxy of nutritional adequacy—while cropland expansion does not, suggesting that such forest conversions may be an ineffective climate adaptation strategy for improving nutrition. Our findings highlight the potential of nutrition-sensitive climate adaptation to enhance yields, promote nutritious cropping choices, and protect remaining forests.

The rising homogeneity of global crop supply has increased vulnerability to climatic and economic disruptions. While substantial work has examined yield variations in relation to climate variability, little is known about the influence of harvested area on production stability. To investigate this, here we take the example of monsoon cereal production in India, which has steadily shifted towards climate-sensitive rice and away from alternative cereals (finger millet, maize, pearl millet, and sorghum). We find that variations in harvested area are significantly associated with current and past price fluctuations for all cereals except rice. This suggests that farmer decisions based on economic factors may exercise great influence in determining variations in harvested area. We also show that optimized allocations of harvested area can reduce climate-induced production loss by 11% or improve farmer net profit by 11% while maintaining calorie production and cropland area. Such improvements would be possible by reducing harvested areas dedicated to rice and increasing areas allocated to alternative cereals. Our findings show that strategies using harvested area to address cereal yield fluctuations and improve farm profits could complement ongoing efforts to improve alternative cereal yields and stabilize cereal production.

AbstractPersistent overuse of water supplies from the Colorado River during recent decades has substantially depleted large storage reservoirs and triggered mandatory cutbacks in water use. The river holds critical importance to more than 40 million people and more than two million hectares of cropland. Therefore, a full accounting of where the river’s water goes en route to its delta is necessary. Detailed knowledge of how and where the river’s water is used can aid design of strategies and plans for bringing water use into balance with available supplies. Here we apply authoritative primary data sources and modeled crop and riparian/wetland evapotranspiration estimates to compile a water budget based on average consumptive water use during 2000–2019. Overall water consumption includes both direct human uses in the municipal, commercial, industrial, and agricultural sectors, as well as indirect water losses to reservoir evaporation and water consumed through riparian/wetland evapotranspiration. Irrigated agriculture is responsible for 74% of direct human uses and 52% of overall water consumption. Water consumed for agriculture amounts to three times all other direct uses combined. Cattle feed crops including alfalfa and other grass hays account for 46% of all direct water consumption.

The Rio Grande-Rio Bravo's flow regime has been highly altered for more than 130 years, yet the river ecosystem still supports important biodiversity including numerous endangered species. More than 80% of water consumed in the basin goes to irrigating farms, but in recent decades, farmers have repeatedly experienced severe water shortages. Given this water-scarce condition, any plans for enhancing environmental flows must be carefully designed to minimize impacts or provide benefits to agriculture. This study describes the development of the Rio Grande-Rio Bravo's first whole-basin hydrologic model-representing both the United States and Mexico portions of the basin-to enable exploration of environmental flow restoration needs and options for meeting these needs. We then demonstrate an analytical process in which environmental flow needs are compared to existing flow conditions to quantify gaps, and then evaluate how those gaps can be filled by reducing farm irrigation needs by shifting to less water-intensive crops and fallowing a portion of existing farmland while maintaining or improving net revenues. In our pilot assessment we find that an improvement of 2.2 m3/s would fill the environmental flow gap for late-summer low-flow conditions at Albuquerque, New Mexico. This flow enhancement is attainable by fallowing 18%-26% of cropland and shifting to more profitable and less water-intensive crops to sustain overall farm revenues.

Food production stability against climate variability and extremes is crucial for food security and is influenced by variations in planted area, harvested area and yield. Yet research has focused on yield responses to climate fluctuations, ignoring how planted area and harvestable fraction (that is, the ratio of planted area to harvested area) affect production stability. Here we apply a time series shock detection approach to county-level data (1978–2020) on seven crops in the United States, finding that shocks (that is, sudden statistically significant declines) in planted area and harvestable fraction co-occur with 51–81% of production shocks, depending on the crop. Decomposing production shock magnitudes, we find that yield fluctuations contribute more for corn (59%), cotton (49%), soybean (64%) and winter wheat (40%), whereas planted area and harvestable fraction have a greater role for others. Additionally, climatic variables explain considerable portions of the variance in planted area (22–30%), harvestable fraction (15–28%) and yield (32–50%). These findings demonstrate that crop production shocks are often associated with fluctuations in planted area and harvestable fraction. This highlights the (largely ignored) importance of producer decision-making about cropping patterns in stabilizing food production against climate variability and emphasizes the need to consider all three production components to improve food system stability.

Irrigated agriculture dominates freshwater consumption globally, but crop production and farm revenues suffer when water supplies are insufficient to meet irrigation needs. In the United States, the mismatch between irrigation demand and freshwater availability has been exacerbated in recent decades due to recurrent droughts, climate change and overextraction that dries rivers and depletes aquifers. Yet, there has been no spatially detailed assessment of the potential for shifting to new crop mixes to reduce crop water demands and alleviate water shortage risks. In this study, we combined modelled crop water requirements and detailed agricultural statistics within a national hydrological model to quantify sub-basin-level river depletion, finding high-to-severe levels of irrigation scarcity in 30% of sub-basins in the western United States, with cattle-feed crops—alfalfa and other hay—being the largest water consumers in 57% of the region’s sub-basins. We also assessed recent trends in irrigation water consumption, crop production and revenue generation in six high-profile farming areas and found that in recent decades, water consumption has decreased in four of our study areas—a result of a reduction in the irrigated area and shifts in the production of the most water-consumptive crops—even while farm revenues increased. To examine the opportunities for crop shifting and fallowing to realize further reductions in water consumption, we performed optimizations on realistic scenarios for modifying crop mixes while sustaining or improving net farm profits, finding that additional water savings of 28–57% are possible across our study areas. These findings demonstrate strong opportunities for economic, food security and environmental co-benefits in irrigated agriculture and provide both hope and direction to regions struggling with water scarcity around the world. Farmer livelihoods and food production are impacted by water shortages in many regions globally. These shortages can be mitigated by changing the mix of crops produced in water-scarce regions, potentially resulting in reduced irrigation needs of 28–57%.

Earth and Space Science Open Archive Presented WorkOpen AccessYou are viewing the latest version by default [v1]Majority of production shocks for major US crops explained by fluctuations in planted and harvested areaAuthorsDongyangWeiiDKyleDavisSee all authors Dongyang WeiiDCorresponding Author• Submitting AuthorUniversity of DelawareiDhttps://orcid.org/0000-0003-0384-4340view email addressThe email was not providedcopy email addressKyle DavisUniversity of Delawareview email addressThe email was not providedcopy email address

Diets exercise great influence over both human and environmental health. While numerous efforts have sought to define and identify sustainable diets, there remains a poor understanding of the extent to which such shifts are feasible when taking into account local dietary preferences. Accounting for 40% of dietary calories and 46% of global cropland, cereals offer an important food group by which culturally appropriate dietary shifts may achieve large sustainability benefits. Here we combine country-specific information on dietary cereal supply with nutrient content values, CO 2 nutrient penalties, and environmental footprints to quantify the outcomes of adopting two feasible dietary shifts—maximizing the share of C4 cereals (e.g. maize, millet, sorghum) based on historical shares and increasing the share of whole grains. Our results show that increasing the share of whole grains can increase nutrient supply (+7% protein, +37% iron, +42% zinc) and overcome the nutrient-depleting effects of elevated CO 2 (eCO 2 ) and that maximizing the share of C4 cereals can substantially reduce environmental burden (−12% greenhouse gas emissions, −11% blue water demand), particularly in Africa and the Middle East. We also find that a combination of the two strategies would likely produce strong co-benefits between increased nutrient supply and reduced environmental impacts with mixed outcomes for offsetting the effects of eCO 2 . Such simultaneous improvements are particularly important for food insecure regions such as West Africa and Southeast Asia. These findings demonstrate important opportunities to identify sustainable diets that incorporate local preferences and cultural acceptability. Such considerations are essential when developing demand-side solutions to achieve more sustainable food systems.

Abstract The El Cañizar de Villarquemado pollen record covers the last part of MIS 6 to the Late Holocene. We use Tolerance-Weighted Averaging Partial Least Squares (TWA-PLS) to reconstruct mean temperature of the coldest month (MTCO) and growing degree days above 0°C (GDD0) and the ratio of annual precipitation to annual potential evapotranspiration (MI), accounting for the ecophysiological effect of changing CO2 on water-use efficiency. Rapid summer warming occurred during the Zeifen-Kattegat Oscillation at the transition to MIS 5. Summers were cold during MIS 4 and MIS 2, but some intervals of MIS 3 had summers as warm as the warmest phases of MIS 5 or the Holocene. Winter temperatures declined from MIS 4 to MIS 2. Changes in temperature seasonality within MIS 5 and MIS 1 are consistent with insolation seasonality changes. Conditions became progressively more humid during MIS 5, and MIS 4 was also humid, although MIS 3 was more arid. Changes in MI and GDD0 are anti-correlated, with increased MI during summer warming intervals. Comparison with other records shows glacial-interglacial changes were not unform across the circum-Mediterranean region, but available quantitative reconstructions are insufficient to determine if east-west differences reflect the circulation-driven precipitation dipole seen in recent decades.

Most techniques for pollen-based quantitative climate reconstruction use modern assemblages as a reference data set. We examine the implication of methodological choices in the selection and treatment of the reference data set for climate reconstructions using Weighted Averaging Partial Least Squares (WA-PLS) regression and records of the last glacial period from Europe. We show that the training data set used is important because it determines the climate space sampled. The range and continuity of sampling along the climate gradient is more important than sampling density. Reconstruction uncertainties are generally reduced when more taxa are included, but combining related taxa that are poorly sampled in the data set to a higher taxonomic level provides more stable reconstructions. Excluding taxa that are climatically insensitive, or systematically overrepresented in fossil pollen assemblages because of known biases in pollen production or transport, makes no significant difference to the reconstructions. However, the exclusion of taxa overrepresented because of preservation issues does produce an improvement. These findings are relevant not only for WA-PLS reconstructions but also for similar approaches using modern assemblage reference data. There is no universal solution to these issues, but we propose a number of checks to evaluate the robustness of pollen-based reconstructions.

Pollen data are widely used to reconstruct past climate changes, using relationships between modern pollen abundance in surface samples and climate at the surface-sample sites as a calibration. Visualization of modern pollen data in multidimensional climate space provides a way to establish that taxon abundances are well behaved before using them in climate reconstructions. Visualization is also helpful for ecological interpretation of variations in pollen abundance in space and time. Here, we present Generalized Additive Models for the distribution of 195 European pollen and pteridophyte spore taxa in a bioclimate space defined by seasonal temperatures (as mean temperature of the coldest month and annual growing degree days) and an annual moisture index. These models can be used to explore the realized climate niche of pollen taxa and to build statistical models for palaeoclimate reconstruction. The data set is released under a Creative Commons BY license. When using the data set, we kindly request that you cite this article.

This manuscript contains some excellent material (e.g. Appendix 1, correcting estimates of moisture for [CO2]) and much less good material (e.g. pollen-based reconstructions, numerical methods, component selection, SI Table 2, no data for the fossil sequence, no pollen diagram showing major taxa, no information about how the sequence has been constructed from the several pollen diagrams published from the sites, no age-depth model). I am surprised that the statistical significance of the reconstructions was not assessed using the Telford Birks (2011, QQSR) randomisation procedure. Such an assessment would provide a critical test of how potentially robust the reconstructions are. Overall I recommend major revisions to some parts plus extending the manuscript to be more complete. It is potentially a very valuable study, it