Information and communication technology (ICT) provides unprecedented opportunities to reduce greenhouse gas (GHG) emissions from passenger transport by avoiding, shifting or improving transport. Research on climate protection through ICT applications in passenger transport mainly focuses on theoretical potentials, is assuming that digitalmobility services replace GHG-intensive transport modes (e.g. car travel), and does not specify the conditions under which decarbonization potentials will materialize. It is known that digitalmobility services can also take a complementary (as opposed to substituting) role in travel or replace non-motorized travel, which can increase GHG emissions. Based on existing literature, we develop a conceptual framework to guide qualitative and quantitative assessments of the relationship between ICT use, passenger transport and GHG emissions. The framework distinguishes three types of effects: (1) First-order effects, GHG impacts of producing, operating and disposing the ICT hardware and software, (2) second-order effects, impacts of ICT on properties of transport modes, transport mode choice and travel demand, and (3) third-order effects, long-term structural changes due to ICT use (e.g. residential relocation). We qualitatively demonstrate the framework at the example of automated driving and discussmethodological challenges in assessments of ICT impacts on passenger transport such as the definition of system boundaries, consideration of socio-demographic characteristics of individuals and the inference of causality. The framework supports researchers in scoping assessments, designing suitable assessment methods and correctly interpreting the results, which is essential to put digitalization in passenger transport at the service of climate protection.

ICT hold significant potential to increase resource and energy efficiencies and contribute to a circular economy. Yet unresolved is whether the aggregated net effect of ICT overall mitigates or aggravates environmental burdens. While the savings potentials have been explored, drivers that prevent these and possible counter measures have not been researched thoroughly. The concept digital sufficiency constitutes a basis to understand how ICT can become part of the essential environmental transformation. Digital sufficiency consists of four dimensions, each suggesting a set of strategies and policy proposals: (a) hardware sufficiency, which aims for fewer devices needing to be produced and their absolute energy demand being kept to the lowest level possible to perform the desired tasks; (b) software sufficiency, which covers ensuring that data traffic and hardware utilization during application are kept as low as possible; (c) user sufficiency, which strives for users applying digital devices frugally and using ICT in a way that promotes sustainable lifestyles; and (d) economic sufficiency, which aspires to digitalization supporting a transition to an economy characterized not by economic growth as the primary goal but by sufficient production and consumption within planetary boundaries. The policies for hardware and software sufficiency are relatively easily conceivable and executable. Policies for user and economic sufficiency are politically more difficult to implement and relate strongly to policies for environmental transformation in general. This article argues for comprehensive policies for digital sufficiency, which are indispensible if ICT are to play a beneficial role in overall environmental transformation. 

Most telecommuting (TC) studies focus on travel impacts and do not consider changes in time spent on non-travel activities (e.g. 'leisure') and the energy impacts of these changes. We demonstrate a time-use approach to assess interrelations between changes in commuting time and time spent on travel and non-travel activities and associated energy impacts. Time-use data analysis shows that spending less time on commuting is associated with more time spent on 'sleep', 'leisure', 'personal, household and family care', 'private travel' and 'eating and drinking'. Substituting car commuting with 'sleep', 'eating and drinking', common 'leisure' and 'personal, household and family care' activities is likely to reduce energy requirements as these are associated with less energy requirements than car commuting. This is different for 'private travel', 'meal preparation at home', and energy-intensive or out-of-home 'leisure' activities, which are associated with relatively high energy requirements. The commute modal split is a key variable in energy impacts of TC, because transport modes differ in their energy requirements. While car commuters can realize high energy savings through TC, for people who usually bike or walk to work, direct energy savings through reduced commuting are zero. Thus, any additional energy impact due to substitute activities, increases net direct energy requirements. Future research should further investigate the relationship between TC and time spent on (non-)travel activities and the marginal energy requirements of these activities. If so, the time-use approach can become key for assessing energy impacts of TC and other applications which impact individual time allocation.

Increasing the service lifetime of mobile Internet-enabled devices (MIEDs) such as smartphones, tablets and laptops is a promising strategy to reduce the number of devices that need to be produced and reduce environmental impacts associated with device production. A broad spectrum of lifetime-extending measures has been explored in literature and in industry practice. In this article, we present an overview of explored measures, discuss challenges in their implementation and environmental impacts of lifetime extension. We find that measures can be distinguished into measures aiming at (1) the improvement of the device design (e.g. modular or durable design of smartphones), (2) device retention (increasing the time a user keeps a device, e.g. by offering repair services or fostering emotional attachment to devices), and (3) recirculation (creating a second life with a different user and/or in a different context, e.g. by refurbishing and reselling devices). The implementation of measures is challenged by trade-offs faced by organizations in the MIED value chain, which specifically occur when revenues depend on the number of new devices produced and sold. Furthermore, measures are subject to rebound and induction effects (e.g. imperfect substitution, re-spending effects), which can compensate for the (theoretical) environmental gains from service lifetime extension. In particular, it is uncertain to what extent a measure actually leads to lifetime extension and eventually reduces primary production of devices (displacement rate). Thus, more systematic research is needed on the feasibility of measures and the conditions under which they effectively contribute to a net reduction of environmental impacts. 

To meet internationally agreed climate protection targets, a drastic reduction of passenger transport greenhouse gas (GHG) emissions is required. The “Avoid-Shift-Improve”-Approach suggests to meet future transport demand by avoiding unnecessary travel, shifting travel to more environmentally-friendly transport modes and improving the environmental performance of transport modes. Digital applications can contribute to both an increase or a decrease of passenger transport GHG emissions, e.g. by avoiding travel, increasing travel or shifting travel to more GHG-intensive or GHG-efficient transport modes. In view of the large number of digital applications in passenger transport and their uncertain impacts on GHG emissions, the aim of this report is to present a review of (1) digital technologies that are used in passenger transport, (2) applications that are supported by digital technologies and (3) their potential impacts on GHG emissions.

We identified nine central categories of digital technologies that shape passenger transport, namely (mobile) end user devices and apps, telecommunication networks, cloud computing, artificial intelligence and big data, geospatial technologies, digital sensors, computer graphics, automation and robotics and blockchain. These technologies support various applications in passenger transport which can be categorized into digital traveler information systems (e.g. trip planning and booking apps), digital shared mobility services (e.g. car or ride sharing), digitally-enabled transport modes that would not exist without digital technologies (e.g. virtual mobility, taxi drones), digital in-vehicle applications (e.g. automated driving), and digital applications for traffic and infrastructure management (e.g. traffic simulations and mobility pricing).

All described applications can have reducing and increasing effects on GHG emissions. Main levers to reduce GHG emissions are (1) a reduction of number of vehicles produced (e.g. through vehicle sharing), (2) a reduction of total travel distances (e.g. through virtual mobility), (3) an increase in the attractiveness of and shift to more GHG-efficient transport modes (e.g. through multimodal mobility platforms), (4) an increase in the utilization of transport modes and a reduction of vehicle kilometers traveled (e.g. through ride sharing), and (5) an increase in the fuel efficiency of vehicles (e.g. through automated driving systems).

In a real-life setting, the impacts of digital applications depend on the interplay between the applications and their design, existing travel patterns and the policy framework in place. In order put digital applications in passenger transport at the service of climate protection, applications and policies have to be aligned in a way that they promote GHG reducing levers. Otherwise, there is a risk that these applications lead to an increase in GHG emissions, e.g. by inducing additional travel or promoting more GHG-intensive transport modes.

Future research should empirically assess the impacts of digital applications on passenger transport and identify the conditions under which decarbonization potentials will materialize. This will support policy makers and market actors to jointly create conditions under which offering digital applications in passenger transport contributes to a net GHG emission reduction and is economically-feasible.

Through virtual presence, information and communication technology (ICT) allows employees to work from places other than their employer’s office and reduce commuting- related environmental effects (telecommuting). Co-working, as a form of telecommuting, has the potential to significantly reduce commuting and is not associated with deficits of working from home (e.g. isolation, lack of focus). However, environmental burden might increase through co-working due to the infrastructure required to set-up and operate the co-working space and potential rebound effects. In this paper, we (1) develop a framework of direct and indirect environmental effects of co- working based on a well-known conceptual framework of environmental effects of ICT and, (2) apply the framework to investigate the case of a co-working living lab established in Stockholm. Based on actual data of the co-working space and interviews conducted with participants, we roughly estimate associated energy impacts. Results show that energy requirements associated with operating the co-working space can counterbalance commute-related energy savings. Thus, in order to realize energy savings co-working should be accompanied with additional energy saving measures such as a net reduction of (heated) floor space (at the CW space, at the employer's office and the co-workers home) and use of energy-efficient transport modes.