Reducing greenhouse gas emissions in agriculture without compromising food security?

To keep global warming possibly below 1.5◦C and mitigate adverse effects of climate change, agriculture, like all other sectors, will have to contribute to efforts in achieving net negative emissions by the end of the century. Cost-efficient distribution of mitigation across regions and economic sectors is typically calculated using a global uniform carbon price in climate stabilization scenarios. However, in reality such a carbon price would substantially affect food availability. Here, we assess the implications of climate change mitigation in the land use sector for agricultural production and food security using an integrated partial equilibrium modelling framework and explore ways of relaxing the competition between mitigation in agriculture and food availability. Using a scenario that limits global warming cost-efficiently across sectors to 1.5◦C, results indicate global food calorie losses ranging from 110–285 kcal per capita per day in 2050 depending on the applied demand elasticities. This could translate into a rise in undernourishment of 80–300 million people in 2050. Less ambitious greenhouse gas (GHG) mitigation in the land use sector reduces the associated food security impact significantly, however the 1.5◦C target would not be achieved without additional reductions outside the land use sector. Efficiency of GHG mitigation will also depend on the level of participation globally. Our results show that if non-Annex-I countries decide not to contribute to mitigation action while other parties pursue their mitigation efforts to reach the global climate target, food security impacts in these non-Annex-I countries will be higher than if they participate in a global agreement, as inefficient mitigation increases agricultural production costs and therefore food prices. Land-rich countries with a high proportion of emissions from land use change, such as Brazil, could reduce emissions with only a marginal effect on food availability. In contrast, agricultural mitigation in high population (density) countries, such as China and India, would lead to substantial food calorie loss without a major contribution to global GHG mitigation. Increasing soil carbon sequestration on agricultural land would allow reducing the implied calorie loss by 65% when sticking to the initially estimated land use mitigation requirements, thereby limiting the impact on undernourishment to 20–75 million people, and storing significant amounts of carbon in soils

Contribution of the land sector to a 1.5 °C world

Acknowledgements The analysis in this study was guided by the valuable feedback and recommendations of expert consultations and interviews, and we extend our gratitude to all those individuals who contributed to our research and analysis: Jeff Atkins (Virginia Commonwealth University), Jonah Busch (Earth Innovation Institute), Peter Ellis (The Nature Conservancy), Jason Funk (Center for Carbon Removal), Trisha Gopalakrishna (The Nature Conservancy), Alan Kroeger (Climate Focus), Bernice Lee (Chatham House), Donna Lee (Climate and Land Use Alliance), Simon Lewis (University College London), Guy Lomax (The Nature Conservancy), Dann Mitchell (University of Bristol), Raoni Rajão (University of Minas Gerais), Joeri Rogelj (IIASA), Carl-Friedrich Schleussner (Climate Analytics), Paul West (University of Minnesota), Graham Wynne (Prince of Wales International Sustainability Unit), Ana Yang (Children’s Investment Fund Foundation) and Dan Zarin (Climate and Land Use Alliance). A special thank you to Esther Chak and Mary-Jo Valentino (Imaginary Office) for designing the figures in this study. This work was generously supported by the Children’s Investment Fund Foundation and the authors’ institutions and funding sources.Peer reviewedPostprin

The marker quantification of the Shared Socioeconomic Pathway 2: A middle-of-the-road scenario for the 21st century

AbstractStudies of global environmental change make extensive use of scenarios to explore how the future can evolve under a consistent set of assumptions. The recently developed Shared Socioeconomic Pathways (SSPs) create a framework for the study of climate-related scenario outcomes. Their five narratives span a wide range of worlds that vary in their challenges for climate change mitigation and adaptation. Here we provide background on the quantification that has been selected to serve as the reference, or ‘marker’, implementation for SSP2. The SSP2 narrative describes a middle-of-the-road development in the mitigation and adaptation challenges space. We explain how the narrative has been translated into quantitative assumptions in the IIASA Integrated Assessment Modelling Framework. We show that our SSP2 marker implementation occupies a central position for key metrics along the mitigation and adaptation challenge dimensions. For many dimensions the SSP2 marker implementation also reflects an extension of the historical experience, particularly in terms of carbon and energy intensity improvements in its baseline. This leads to a steady emissions increase over the 21st century, with projected end-of-century warming nearing 4°C relative to preindustrial levels. On the other hand, SSP2 also shows that global-mean temperature increase can be limited to below 2°C, pending stringent climate policies throughout the world. The added value of the SSP2 marker implementation for the wider scientific community is that it can serve as a starting point to further explore integrated solutions for achieving multiple societal objectives in light of the climate adaptation and mitigation challenges that society could face over the 21st century

A review of successful climate change mitigation policies in major emitting economies and the potential of global replication

This article reviews climate change mitigation policies implemented in five major emitting economies: China, the European Union, India, Japan and the United States. It analyses their historical performance in terms of energy system and greenhouse gas emissions indicators. In cases where policies aim to reduce future emissions, their target performance levels are assessed. The review centres on the sectors of electricity generation, passenger vehicles, freight transport, forestry, industry, buildings, agriculture, and oil and gas production. Most focus countries have implemented successful policies for renewable energy, fuel efficiency, electrification of passenger vehicles, and forestry. For other sectors, information is limited or very heterogeneous (e.g. buildings, appliances, agriculture) or there are few comprehensive policies in place (e.g. industry). The article further presents an explorative emissions scenario developed under the assumption that all countries will replicate both the observed trends in sector-level indicators and the trends that policies for future emissions reductions aspire to achieve. It shows that the global replication of sector progress would reduce greenhouse gas emissions by 2030 by about 20% compared to a current policies scenario. All countries analysed would overachieve the emissions reduction targets in their post-2020 climate targets. However, the resulting reduction in global emissions by 2030 would still not be sufficient to keep the world on track for a global cost-effective pathway that keeps temperature increase below 2°C. The findings of this study emphasise the need for transformative policies to keep the Paris Agreement temperature limit within reach

On fair, effective and efficient REDD mechanism design

The issues surrounding 'Reduced Emissions from Deforestation and Forest Degradation' (REDD) have become a major component of continuing negotiations under the United Nations Framework Convention on Climate Change (UNFCCC). This paper aims to address two key requirements of any potential REDD mechanism: first, the generation of measurable, reportable and verifiable (MRV) REDD credits; and secondly, the sustainable and efficient provision of emission reductions under a robust financing regime

Cost and attainability of meeting stringent climate targets without overshoot

Global emissions scenarios play a critical role in the assessment of strategies to mitigate climate change. The current scenarios, however, are criticized because they feature strategies with pronounced overshoot of the global temperature goal, requiring a long-term repair phase to draw temperatures down again through net-negative emissions. Some impacts might not be reversible. Hence, we explore a new set of net-zero CO2 emissions scenarios with limited overshoot. We show that upfront investments are needed in the near term for limiting temperature overshoot but that these would bring long-term economic gains. Our study further identifies alternative configurations of net-zero CO2 emissions systems and the roles of different sectors and regions for balancing sources and sinks. Even without net-negative emissions, CO2 removal is important for accelerating near-term reductions and for providing an anthropogenic sink that can offset the residual emissions in sectors that are hard to abate

Land-based implications of early climate actions without global net-negative emissions

Delaying climate mitigation action and allowing a temporary overshoot of temperature targets require large-scale carbon dioxide removal (CDR) in the second half of this century that may induce adverse side effects on land, food and ecosystems. Meanwhile, meeting climate goals without global net-negative emissions inevitably needs early and rapid emission reduction measures, which also brings challenges in the near term. Here we identify the implications for land-use and food systems of scenarios that do not depend on land-based CDR technologies. We find that early climate action has multiple benefits and trade-offs, and avoids the need for drastic (mitigation-induced) shifts in land use in the long term. Further long-term benefits are lower food prices, reduced risk of hunger and lower demand for irrigation water. Simultaneously, however, near-term mitigation pressures in the agriculture, forest and land-use sector and the required land area for energy crops increase, resulting in additional risk of food insecurity

Towards harmonizing competing models: Russian forests' net primary production case study

This paper deals with the issue of reconciling competing stochastic estimates provided by independent sources. We employ an integration method based on a principle of mutual compatibility of prior estimates. The method does not take into account credibility of the sources of the estimates, including their past performance. The quality of integration is evaluated in terms of change in the probability distribution. We use the method to integrate two types of estimates of the annual Net Primary Production (NPP) of the forest ecosystems in seven bioclimatic zones in Russia. The estimates are generated based on an empirical landscape-ecosystem approach and on an ensemble of dynamic global vegetation models; the gaps in thei estimates reach 23%. Elimination of the gaps may help better quantify the input of the terrestrial ecosystems to the global carbon cyce. The main result of this paper is the evidence of applicability of the method for selection a set of candidates for credible integrated estimates of uncertain ecological parameters (like forest NPP) integrating prior estimates

Лінійна оптимізація лісокористування для динамічної рекурсивної моделі

Our study presents development of a forest management model based on LP which can be easily integrated into a large-scale dynamic recursive model and contain the instruments providing future consideration for harvesting plans under recursive limitations. We introduce a general structure and simulation algorithm of the model. The forest management algorithm was tested applying historical data of Ukrainian forests. Obtained modeling results demonstrate a correct age class transition. They prove as well adequacy of utilizing benefit losses and delay costs as regulative mechanisms for temporal allocation of forest harvesting. As far as statistic data concerning age structure of Ukrainian forests are not publicly available, FesT was validated by comparing projected forest age structure with results of Global Forest Model (G4M).The comparison shows that the projections of both models are fairly close to each other. The divergence between the results can be explained by difference in forest management modelling approach.В исследовании представлена разработка модели оптимизации лесопользования на основе линейного программирования, которая может быть легко интегрирована в сложные динамические рекурсивные модели и которая содержит инструменты, обеспечивающие учет будущего состояния леса во время текущей заготовки древесины при наличии рекурсивных ограничений. Представлена общая структура и алгоритм моделирования. Проведено сравнение результатов двух моделей леса и определены основные пути дальнейшего совершенствования разработанной модели лесопользования.У дослідженні представлено розроблення моделі оптимізації лісокористування на основі лінійного програмування, яка може бути легко інтегрована у складні динамічні рекурсивні моделі і яка містить інструменти, що забезпечують врахування майбутнього стану лісу під час поточної заготівлі деревини за наявності рекурсивних обмежень. Представлено загальну структуру і алгоритм моделювання. Проведено порівняння результатів двох лісових моделей та визначено основні шляхи подальшого вдосконалення розробленої моделі лісокористування