Bastien Girod

More or Better? A Model for Changes in Household Greenhouse Gas Emissions Due to Higher Income

Households exert an important influence on total greenhouse gas (GHG) emissions. Therefore, their consumption behavior is of interest in evaluations of climate policy options and projections of future emission paths. While most evaluations of household consumption and its emissions are based on expenditure only, we use a household consumption model based on functional units (e.g., kg food, person kilometers, living square meters). The goal of this article is to assess changes in consumption with increasing affluence level of households and to compare the allocation of GHG emissions to monetary versus functional units. We find that (1) the model based on functional units provides good bottom-up estimates for greenhouse emissions of Swiss households; (2) quality (price per functional unit) increases with income for many consumption categories, and therefore using functional instead of monetary units leads to a lower increase of greenhouse gas emissions with income; (3) the relevance of GHG emissions from goods and mobility will increase. We conclude that using household models based on monetary units only overestimates the impact of marginal consumption and neglects the potential of decoupling income and environmental impact by consuming better instead of more. For sustainable consumption, research and policy should aim at preventing goods of higher quality from having higher environmental impact in order to benefit from the increasing quality orientation with rising income.

Climate impact of transportation A model comparison

Transportation contributes to a significant and rising share of global energy use and GHG emissions. Therefore modeling future travel demand, its fuel use, and resulting CO2 emission is highly relevant for climate change mitigation. In this study we compare the baseline projections for global service demand (passenger-kilometers, ton-kilometers), fuel use, and CO2 emissions of five different global transport models using harmonized input assumptions on income and population. For four models we also evaluate the impact of a carbon tax. All models project a steep increase in service demand over the century. Technology change is important for limiting energy consumption and CO2 emissions, the study also shows that in order to stabilise or even decrease emissions radical changes would be required. While all models project liquid fossil fuels dominating up to 2050, they differ regarding the use of alternative fuels (natural gas, hydrogen, biofuels, and electricity), because of different fuel price projections. The carbon tax of 200 USD/tCO2 in 2050 stabilizes or reverses global emission growth in all models. Besides common findings many differences in the model assumptions and projections indicate room for further understanding long-term trends and uncertainty in future transport systems.

Global Climate targets and future consumption level: An evaluation of the required GHG intensity

Discussion and analysis on international climate policy often focuses on the rather abstract level of total national and regional greenhouse gas (GHG) emissions. At some point, however, emission reductions need to be translated to consumption level. In this article, we evaluate the implications of the strictest IPCC representative concentration pathway for key consumption categories (food, travel, shelter, goods, services). We use IPAT style identities to account for possible growth in global consumption levels and indicate the required change in GHG emission intensity for each category (i.e.?GHG emission per calorie, person kilometer, square meter, kilogram, US dollar). The proposed concept provides guidance for product developers, consumers and policymakers. To reach the 2??C climate target (2.1?tCO2-eq. per capita in 2050), the GHG emission intensity of consumption has to be reduced by a factor of 5 in 2050. The climate targets on consumption level allow discussion of the feasibility of this climate target at product and consumption level. In most consumption categories products in line with this climate target are available. For animal food and air travel, reaching the GHG intensity targets with product modifications alone will be challenging and therefore structural changes in consumption patterns might be needed. The concept opens up possibilities for further research on potential solutions on the consumption and product level to global climate mitigation.

Regional differences in mitigation strategies: an example for passenger transport

This paper shows the importance of including region-specific circumstances in long-term climate change mitigation strategies, by example of a modeling exercise of the transport sector. Important emission reduction options in the transport sector include biofuels, electric vehicles and efficiency standards. The most effective combination of these options depends, among others, on the availability of biofuels, the effectiveness of efficiency standards, and the (expected) emission intensity of the power sector—all of which differ between regions. Differences in climate policies between regions influence these factors. For instance, fuel efficiency standards slowdown the long-term transition in regions where plugin hybrid electric cars compete with gasoline cars (such as the USA or Europe) by decreasing the costs for driving gasoline costs and therefore in fact increase long-term emissions. Another example is that promoting electric vehicles is less effective in regions which are expected to rely heavily on fossil fuels for power generation, such as South Africa, China and India. Based on these findings from the TIMER energy model, we introduce an indicative region-specific framework for assessing mitigation strategies for the transport sector up to 2050, for different ambition levels of climate policy.

Corrigendum: Global climate targets and future consumption level: an evaluation of the required GHG intensity

Discussion and analysis on international climate policy often focuses on the rather abstract level of total national and regional greenhouse gas (GHG) emissions. At some point, however, emission reductions need to be translated to consumption level. In this article, we evaluate the implications of the strictest IPCC representative concentration pathway for key consumption categories (food, travel, shelter, goods, services). We use IPAT style identities to account for possible growth in global consumption levels and indicate the required change in GHG emission intensity for each category (i.e. GHG emission per calorie, person kilometer, square meter, kilogram, US dollar). The proposed concept provides guidance for product developers, consumers and policymakers. To reach the 2 C climate target (2.1 tCO2-eq. per capita in 2050), the GHG emission intensity of consumption has to be reduced by a factor of 5 in 2050. The climate targets on consumption level allow discussion of the feasibility of this climate target at product and consumption level. In most consumption categories products in line with this climate target are available. For animal food and air travel, reaching the GHG intensity targets with product modifications alone will be challenging and therefore structural changes in consumption patterns might be needed. The concept opens up possibilities for further research on potential solutions on the consumption and product level to global climate mitigation.