Mode, Load, And Specific Climate Impact from Passenger Trips

The climate impact from a long-distance trip can easily vary by a factor of 10 per passenger depending on mode choice, vehicle efficiency, and occupancy. In this paper we compare the <i>specific climate impact</i> of long-distance car travel with coach, train, or air trips. We account for both, CO₂ emissions and short-lived climate forcers. This particularly affects the ranking of aircraft’s climate impact relative to other modes. We calculate the specific impact for the Global Warming Potential and the Global Temperature Change Potential, considering time horizons between 20 and 100 years, and compare with results accounting only for CO₂ emissions. The car’s fuel efficiency and occupancy are central whether the impact from a trip is as high as from air travel or as low as from train travel. These results can be used for carbon-offsetting schemes, mode choice and transportation planning for climate mitigation

Specific Climate Impact of Passenger and Freight Transport

Emissions of short-lived species contribute significantly to the climate impact of transportation. The magnitude of the effects varies over time for each transport mode. This paper compares first the absolute climate impacts of current passenger and freight transportation. Second, the impacts are normalized with the transport work performed and modes are compared. Calculations are performed for the integrated radiative forcing and mean temperature change, for different time horizons and various measures of transport work. An unambiguous ranking of the specific climate impact can be established for freight transportation, with shipping and rail having lowest and light trucks and air transport having highest specific impact for all cases calculated. Passenger travel with rail, coach or two- and three-wheelers has on average the lowest specific climate impact also on short time horizons. Air travel has the highest specific impact on short-term warming, while on long-term warming car travel has an equal or higher impact per passenger-kilometer

Climate Effects of Emission Standards: The Case for Gasoline and Diesel Cars

Passenger transport affects climate through various mechanisms involving both long-lived and short-lived climate forcers. Because diesel cars generally emit less CO₂ than gasoline cars, CO₂ emission taxes for vehicle registrations and fuels enhance the consumer preference for diesel cars over gasoline cars. However, with the non-CO₂ components, which have been changed and will be changed under the previous and upcoming vehicle emission standards, what does the shift from gasoline to diesel cars mean for the climate mitigation? By using a simple climate model, we demonstrate that, under the earlier emissions standards (EURO 3 and 4), a diesel car causes a larger warming up to a decade after the emissions than a similar gasoline car due to the higher emissions of black carbon and NO_X (enhancing the O₃ production). Beyond a decade, the warming caused by a diesel car becomes, however, weaker because of the lower CO₂ emissions. As the latter emissions standards (EURO 5 and 6) are phased in, the short-term warming due to a diesel car becomes smaller primarily due to the lower black carbon emissions. Thus, although results are subject to restrictive assumptions and uncertainties, the switch from gasoline to diesel cars encouraged by CO₂ taxes does not contradict with the climate mitigation focusing on long-term consequences

Climate Penalty for Shifting Shipping to the Arctic

The changing climate in the Arctic opens new shipping routes. A shift to shorter Arctic transit will, however, incur a climate penalty over the first one and a half centuries. We investigate the net climate effect of diverting a segment of Europe–Asia container traffic from the Suez to an Arctic transit route. We find an initial net warming for the first one-and-a-half centuries, which gradually declines and transitions to net cooling as the effects of CO₂ reductions become dominant, resulting in climate mitigation only in the long term. Thus, the possibilities for shifting shipping to the Arctic confront policymakers with the question of how to weigh a century-scale warming with large uncertainties versus a long-term climate benefit from CO₂ reductions