Sara Ohrel

Climate change impacts on US agriculture and forestry: benefits of global climate stabilization

United States. Environmental Protection Agency. Climate Change Division (Contract EP-BPA-12-H-0023, Call Order EP-B13H-00143)

Global mitigation potential and costs of reducing agricultural non-CO2 greenhouse gas emissions through 2030

Abstract Agricultural emissions account for 53% of 2010 global non-CO2 emissions and are projected to increase substantially over the next 20 years, especially in Asia, Latin America and Africa. While agriculture is a substantial source of emissions, it is also generally considered to be a potential source of cost-effective non-CO2 GHG abatement. Previous “bottom-up” analyses provided marginal abatement cost (MAC) curves for use in modeling these options within economy-wide and global mitigation analyses. In this paper, we utilize updated economic and biophysical data and models developed by the US Environmental Protection Agency (EPA) to investigate regional mitigation potential for major sources of agricultural GHG emissions. In addition, we explore mitigation potential available at costs at or below the estimated benefits of mitigation, as represented by the social cost of carbon. Key enhancements over previous regional assessments include incorporation of additional mitigation options, updated baseline emissions projections, greater spatial disaggregation, and development of MAC curves through 2030. For croplands and rice cultivation, biophysical, process-based models (DAYCENT and DNDC) are used to simulate yields and net GHG emissions under baseline and mitigation scenarios while the livestock sector is modeled by applying key mitigation options to baselines compiled by EPA. MAC curves are generated accounting for net GHG reductions, yield effects, livestock productivity effects, commodity prices, labor requirements, and capital costs where appropriate. MAC curves are developed at the regional level and reveal large potential for non-CO2 GHG mitigation at low carbon prices, especially in Asia.

Global climate change impacts on forests and markets

This paper develops an economic analysis of climate change impacts in the global forest sector. It illustrates how potential future climate change impacts can be integrated into a dynamic forestry economics model using data from a global dynamic vegetation model, the MC2 model. The results suggest that climate change will cause forest outputs (such as timber) to increase by approximately 30% over the century. Aboveground forest carbon storage also is projected to increase, by approximately 26 Pg C by 2115, as a result of climate change, potentially providing an offset to emissions from other sectors. The effects of climate mitigation policies in the energy sector are then examined. When climate mitigation in the energy sector reduces warming, we project a smaller increase in forest outputs over the timeframe of the analysis, and we project a reduction in the sink capacity of forests of around 12 Pg C by 2115.

Global mitigation of non-CO2 greenhouse gases: marginal abatement costs curves and abatement potential through 2030

Abstract Greenhouse gases (GHGs) other than carbon dioxide (CO2) play an important role in the effort to understand and address global climate change. Approximately 25% of Global warming potential-weighted GHG emissions in the year 2005 comprise the non-CO2 GHGs. The report, Global Mitigation of Non-CO2 Greenhouse Gases: 2010–2030 provides a comprehensive global analysis and resulting data-set of marginal abatement cost curves that illustrate the abatement potential of non-CO2 GHGs by sector and by region. The basic methodology – a bottom-up, engineering cost approach – builds on the baseline non-CO2 emissions projections published by EPA, applying abatement options to the emissions baseline in each sector. The results of the analysis are MAC curves that reflect aggregated breakeven prices for implementing abatement options in a given sector and region. Among the key findings of the report is that significant, cost-effective abatement exists from non-CO2 sources with abatement options that are available today. Without a price signal (i.e. at

Will U.S. Forests Continue to Be a Carbon Sink

0/tCO2e), the global abatement potential is greater than 1800 million metric tons of CO2 equivalent. Globally, the energy and agriculture sectors have the greatest potential for abatement. Among the non-CO2 GHGs, methane has the largest abatement potential. Despite the potential for project level cost savings and environmental benefits, barriers to mitigating non-CO2 emissions continue to exist. This paper will provide an overview of the methods and key findings of the report.

Evaluating the effects of climate change on US agricultural systems: sensitivity to regional impact and trade expansion scenarios

This paper develops structural dynamic methods to project future carbon fluxes in forests. These methods account for land management changes on both the intensive and extensive margins, both of which are critical components of future carbon fluxes. When implemented, the model suggests that U.S. forests remain a carbon sink through most of the coming century, sequestering 128 Tg C y−1. Constraining forestland to its current boundaries and constraining management to current levels reduce average sequestration by 25 to 28 Tg C y−1. An increase in demand leads to increased management and greater sequestration in forests. The results are robust to climate change. (JEL Q23, Q54)

Overview of the Special Issue: A Multi-Model Framework to Achieve Consistent Evaluation of Climate Change Impacts in the United States

Agriculture is one of the sectors that is expected to be most significantly impacted by climate change. There has been considerable interest in assessing these impacts and many recent studies investigating agricultural impacts for individual countries and regions using an array of models. However, the great majority of existing studies explore impacts on a country or region of interest without explicitly accounting for impacts on the rest of the world. This approach can bias the results of impact assessments for agriculture given the importance of global trade in this sector. Due to potential impacts on relative competitiveness, international trade, global supply, and prices, the net impacts of climate change on the agricultural sector in each region depend not only on productivity impacts within that region, but on how climate change impacts agricultural productivity throughout the world. In this study, we apply a global model of agriculture and forestry to evaluate climate change impacts on US agriculture with and without accounting for climate change impacts in the rest of the world. In addition, we examine scenarios where trade is expanded to explore the implications for regional allocation of production, trade volumes, and prices. To our knowledge, this is one of the only attempts to explicitly quantify the relative importance of accounting for global climate change when conducting regional assessments of climate change impacts. The results of our analyses reveal substantial differences in estimated impacts on the US agricultural sector when accounting for global impacts vs. US-only impacts, particularly for commodities where the United States has a smaller share of global production. In addition, we find that freer trade can play an important role in helping to buffer regional productivity shocks.