Agriculture is under significant pressure to meet current and future food demands. Food consumption growth and climate change push the system to produce more food with the same resources. Irrigation is a key strategy to producing higher yields but current practices are already consuming non-renewable water, threatening the natural and human ecosystem. Desalination – the conversion of saltwater from to freshwater – could help ease constraints on irrigation resources, eliminate unsustainable withdrawals and improve yields in a more difficult climate for food producers (for example in increasingly drier regions). However the extent to which desalination can be deployed, and its associated impacts at a global level is largely unquantified. Using data from 172 countries, We estimate the global demand for desalinated irrigation water in 2050 accounting for climate change and varying blue water availability. We assume this water is used to replace both unsustainably sourced freshwater and to meet irrigation requirements under climatic changes. We assess its cost, energy requirement and the brine produced (an environmental impact from desalination). Results indicate that desalinated water could sustainably feed an additional 500 million to 1 billion people when replacing unsustainable blue water withdrawals within the current system and up to 3.5-5 billion people when providing the water resources to close yield gaps. The annual cost of water is significantly higher than current irrigation at 160-2000 billion euros. The use of desalination at a global scale is unlikely due to prohibitive costs and energy requirements. The feasibility of desalination increases with future technological advancements, increasing water scarcity, decreasing costs, and renewable energy integration. However, challenges such as brine disposal and socio-economic constraints need to be solved. We anticipate that desalinated irrigation is looked at as a niche pathway to provide necessary water resources next to storage fed irrigation and irrigation water application efficiency improvements.

The food system emits one third of anthropogenic greenhouse gas (GHG) emissions and is projected to contribute 0.9 °C to end-of-century warming. It is also a primary source of methane; a powerful short-lived climate forcer (SLCF) and the second-most important GHG. Most food system methane emissions result from livestock production and is biogenic (part of the short carbon cycle). As such, livestock emission reductions can actively lower surface temperatures. Despite this, the livestock sector’s current commitments do not meet the IPCC’s 2035 global emissions reduction target. Here, we use the reduced-complexity climate model MAGICC to show that reduction trajectories identified by expert-elicitation for a livestock sector compliant with the Paris Agreement would avoid up to 0.42 °C warming by 2100. Specifically, a reduction in methane emission contributes 76.6% to this cooling in 2050 (of a total of 0.17 °C). Climate studies typically report emissions using GWP100, which underestimates the warming potential of SLCFs in the short term. We assess various climate metrics’ performance relative to MAGICC outcomes, and find better performance for target-aligned time horizons (for both 1.5 °C and 2.0 °C). Our findings reinforce the scientific consensus that reductions in livestock emissions are unavoidable in meeting targets and developing climate policy.

In the spirit of equity, all humans should be entitled to a life congruous with a very high level of well-being. The development needed to achieve this would however heavily rely on manufactured assets, the production of which negatively impacts the climate system. Both efficiency- and sufficiency-based strategies have been put forward as solutions to reduce greenhouse gas remissions. Assessing their respective and combined effectiveness in supporting the realization of a fair and sustainable future is essential to guide future policy-making. Here I show that combining both would minimize the risk of a global warming beyond 1.5-2˚C while allowing developing regions, particularly Africa and Asia, to sufficiently raise the well-being of their citizens. Comparing different effort-sharing approaches, I further show that this sustainable development can be supported in international climate negotiations by adopting the Human Development Index (HDI) as a proxy for equitably allocating the remaining carbon budget (RCB). This supports research advocating for equating development with human well-being, rather than economic growth, and thus the introduction of demand-side interventions to reduce emissions. The ensuing discussion also points to need to strategically invest in assets in order to prevent unsustainable lock-ins and additional stranded assets.

The growing demand for food production and the global developments regarding the intensification and mechanization of agriculture are likely to affect material use in the agricultural sector in some way in the future. This study addressed a research gap regarding the current and future material requirements of the global agricultural system, and it represents a first attempt to estimate the size and composition of the current global material stock embedded in agricultural field machinery. The study also explored the potential future developments of this material stock in five Shared Socioeconomic Pathways (SSPs) through a material scenario analysis, which utilized scenario data generated by an integrated assessment model IMAGE. Available country-level data on the number of machinery in use was linked to agricultural production data through the calculation of ‘mechanization factors’, which describe the relationship of the size of the in-use machinery stock and the annual production quantities of a country. Regionally aggregated mechanization factors were used in combination with regional production data for the estimation of the total numbers of different field machinery currently in use in 26 world regions. These numbers were combined with literature-based estimates of the average material compositions and masses of different types of agricultural field machinery to quantify their current in-use material stocks. Steel (121 Mt), ductile iron (86 Mt), and rubber (21 Mt) were identified as the largest global material stocks of agricultural field machinery, and the largest shares of the materials were found in tractors and combine harvesters. The results of the quantification of the current material stock were incorporated in a material scenario analysis in combination with IMAGE scenario data on agricultural production in the different SSPs. The scenario analysis involved two scenario models with distinct assumptions concerning the development of mechanization levels over time. Depending on the SSP scenario and the model assumptions, the results of the scenario analysis indicated a 50 to 200 percent growth in the global material stock of agricultural machinery by the year 2100. While the scenario analysis assumed the current agricultural practices and technologies to maintain their importance in the future, the study also explored some newer developments taking place in the global agricultural system and the ways they might influence the material stock of agricultural machinery in the future.