Degrowth scenarios for emissions neutrality

The global emission mitigation potential of avoiding waste and product lifespan extension by Chinese households

This paper examines the emission mitigation potential of Chinese households' low-carbon behavior by 2030 through a global carbon footprint scenario analysis. The emission reduction effect is estimated by comparing the projected global emissions in 2030 in a lifestyle emulation scenario and a low-carbon scenario, in which Chinese households adopt low-carbon consumption behaviors. Lifestyle emulation is modeled based on what we call "world Engel curves", which describe how the expenditure share of a certain consumption good depends on the total per capita expenditures for household consumption (which depends on income). By including a dynamic link between household lifestyle changes and GDP, we then obtain the emission projections under different scenarios in 2030, based on the historical data for 49 countries from 1995 to 2011 from EXIOBASE. Our results show that adopting a mild low-carbon lifestyle by households helps only little in terms of reducing GHG emissions. Reducing avoidable waste and expanding the lifetime of products are not enough to help meeting the 2 °C goal. More drastic changes are required.

Efficiency traps beyond the climate crisis: exploration-exploitation trade-offs and rebound effects

Higher levels of economic activity are often accompanied by higher energy use and consumption of natural resources. As fossil fuels still account for 80% of the global energy mix, energy consumption remains closely linked to greenhouse gas (GHG) emissions and thus to climate change. Under the assumption of sufficiently elastic demand, this reality of global economic development based on permanent growth of economic activity, brings into play the Jevons Paradox, which hypothesises that increases in the efficiency of resource use leads to increases in resource consumption. Previous research on the rebound effects has limitations, including a lack of studies on the connection between reinforcement learning and environmental consequences. This paper develops a mathematical model and computer simulator to study the effects of micro-level exploration-exploitation strategies on efficiency, consumption and sustainability, considering different levels of direct and indirect rebound effects. Our model shows how optimal exploration-exploitation strategies for increasing efficiency can lead to unsustainable development patterns if they are not accompanied by demand reduction measures, which are essential for mitigating climate change. Moreover, our paper speaks to the broader issue of efficiency traps by highlighting how indirect rebound effects not only affect primary energy (PE) consumption and GHG emissions, but also resource consumption in other domains. By linking these issues together, our study sheds light on the complexities and interdependencies involved in achieving sustainable development goals. This article is part of the theme issue 'Climate change adaptation needs a science of culture'.

Achieving decent living standards in emerging economies challenges national mitigation goals for CO2 emissions

Emerging economies, low- and middle-income countries experiencing rapid population and GDP growth, face the challenge of improving their living standards while stabilizing CO2 emissions to meet net-zero goals. In this study, we quantify the CO2 emissions required for achieving decent living standards (DLS) in emerging economies. The results show that, compared to other regions, achieving DLS in emerging Asian and African economies will result in more additional CO2 emissions, particularly in the DLS indicators of Mobility and Electricity. Achievement of DLS in emerging economies will result in 8.6 Gt of additional CO2 emissions, which should not jeopardize global climate targets. However, a concerning trend arises as more than half of the emerging economies (62 out of 121) will face substantial challenges in aligning their expected emission growth for achieving DLS with their national emission mitigation targets.

The Effects on Energy Markets of Achieving a 1.5 °C Scenario

Net zero emission scenarios are aligned with the criteria for the Paris Agreement to keep global warming below 1.5 °C. By soft-linking an energy model with a macroeconomic model, we create a similar pathway to the net zero emission scenario from the International Energy Agency (IEA) to 2050 both of demand for fossil fuels and total CO₂ emissions. Soft-linking entails that we insert endogenous variables from one model into the other model. We implement measures such as CO₂ taxes, improved energy efficiency, more renewables in electricity production and other sectors, easier substitution between electricity and fossil fuels for final users, and drastically limiting future production of oil, gas and coal. Our conclusion is that net zero is possible by introducing very strict measures, e.g., a high rate of energy efficiency improvement, far above what has been achieved in the past. While our partial equilibrium energy model, similar to the IEA model, overlooks the potential rebound effects, i.e., more energy used by consumers due to lower prices caused by energy efficiency improvement, our macroeconomic model does capture the rebound effects and has to implement stricter supply-side measures to reduce fossil fuel use to achieve the 1.5 °C scenario.

An Equality-Based Approach to Analysing the Global Food System's Fair Share, Overshoot, and Responsibility for Exceeding the Climate Change Planetary Boundary

The climate catastrophe is being caused by human effects on earth system processes that are surpassing several planetary boundaries. This crisis is driven significantly by the global food system. It has been increasing over recent years, yet food systems are essential in upholding food and nutrition security. This study proposed a novel method for enumerating national contributions to the cessation of the climate crisis by approximating nations’ aggregate greenhouse gas (GHG) emissions from food systems, within the equitable and sustainable planetary boundaries of climate change. This study included 221 nations, which were grouped as per their human development index (HDI) categories, income groups, and continental locations. During 1990−2018, the annual fair share, overshoot of emissions, and collective historical responsibility in the world of each country were assessed. There was a 22.52% increase in overshooting of GHG emissions from the global food system, starting in 1990. A group of 15 countries, including Brazil, China, Indonesia, and the U.S.A., were responsible for >67% of global overshoot. The primary liability is borne by countries with upper-, middle-, and high-income economies, and high to very-high HDI groups, as well as Asia and South America. Countries such as India, China, the Democratic Republic of the Congo, and others have steadily increased their share of responsibility over the last 28 years. More than 76% of countries in the world, mostly from Africa, Europe, and Asia, proved to be absolute overshooters. After contextualising the study’s findings, the global food system’s decarbonization and its limits were discussed; some recommendations for prospective research were also offered. It appears that academics, governments, and policymakers should start concentrating more on reshaping and redesigning the global food system to be climate-friendly (i.e., a carbon-neutral food system), whilst being able to fairly allocate food and nutrition security to achieve long-term Sustainable Development Goal 2 (SDG 2).