Previous transportation fuel life cycle assessment studies have not fully accounted for the full variability in the crude oil transport stage, for example, transporting a light crude through a high-diameter pipeline, vs transporting a heavy crude through a small-diameter pipeline. We develop a first-principles, fluid mechanics-based crude oil pipeline transportation emissions model (COPTEM) that calculates the greenhouse gas (GHG) emissions associated with pipeline transport as a function of crude oil parameters, pipeline dimensions, and external factors. Additionally, we estimate the emissions associated with the full life cycle of pipeline construction, maintenance, and disposal. This model is applied to an inventory of 62 major Canadian and U.S. pipelines (capacity greater than 100 000 barrels/day) to estimate the variability of GHG emissions associated with pipeline transportation. We demonstrate that pipeline GHG emissions intensities range from 0.23 to 20.3 g COe/(bbl·km), exhibiting considerably greater variability than data reported in other studies. A sensitivity analysis demonstrates that the linear velocity of crude transport and pipeline diameter are the most impactful parameters driving this variability. To illustrate one example of how COPTEM can be used, we develop an energy efficiency gap analysis to investigate the possibilities for more efficient pipeline transport of crude oil.

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Climate change will likely impact smallholder farmer livelihoods substantially. However, empirical evidence is inconclusive regarding how increased climate stress affects smallholder farmers' deployment of various livelihood strategies, including rural-urban migration. Here we use an agent-based model to show that in a South Asian agricultural community experiencing a 1.5 o C temperature increase by 2050, climate impacts are likely to decrease household income in 2050 by an average of 28 percent, with fewer households investing in both economic migration and cash crops, relative to a stationary climate. Pairing a small cash transfer with risk transfer mechanisms significantly increases the adoption of migration and cash crops, improves community incomes, and reduces community inequality. While specific results depend on contextual factors such as risk preferences and climate risk exposure, these interventions are robust in improving adaptation outcomes and alleviating immobility by addressing the intersection of risk aversion, financial constraints, and climate impacts. Climate change is likely to impact the livelihoods of many of the world's 500 million smallholder farming households [1], particularly with projected increases in drylands populations [2]. Migration represents one of several adaptation strategies that farmers could deploy in the face of climate stress [3], and there is mixed evidence on the extent to which climate change may positively or negatively impact migration flows [4, 5, 6]. Uncertainty regarding future climate adaptation policies [7], including new financial instruments to An Agent-Based Model to Simulate Farmer Livelihood DecisionsWe develop an ABM that examines livelihood decisions among smallholder farming households under increasing climate stress. Households are the main decision-making entity, and choose between multiple livelihood strategies characterized by different income distributions, including on-farm options and rural-urban migration (Fig. 1a). Decision-making is grounded in the theory of the New Economics of Labour Migration (NELM), which posits

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