Today’s global road emissions have a strong and long-lasting effect on climate. After 100 years these emissions will lead to a temperature increase that is six times greater than the temperature increase from today’s air transport, according to the CICERO study "Global temperature responses to current emissions from the transport sectors" published in Proceedings of the National Academy of Sciences (PNAS). The study includes the effects of all climate-relevant components of the emissions, not only CO2.
“Among the transport sectors, road transport has a strongly dominating temperature effect, both on short and longer terms,” says Jan Fuglestvedt, researcher at CICERO in Oslo, Norway.
Total global emissions
“It is important to underline that the study looks at the effect of the total global emissions, not emissions per passenger kilometer,” says Terje Berntsen, the other researcher behind the study.
The researchers will calculate climate impacts per passenger kilometer in a later study.
The study has investigated how the global emissions from different transport sectors (road, rail, shipping, and aviation) in year 2000 affect the future temperature. While air transport has some strong climate effects that decrease relatively quickly over time, emissions from road transport have a strong and long-lasting effect on climate. The reason is the much larger total fuel consumption and thus higher CO2 emissions from road traffic, while for aviation there is a strong short-term warming by aviation induced contrails and cirrus clouds.
Air transport effects short lasting
“In contrast to road transport, air transport has several strong, but short lasting, effects on the global temperature,” says Fuglestvedt. “But there are large uncertainties in our understanding of these effects. It is important to work towards reducing this uncertainty.”
Current shipping emissions differ from emissions from the road and aviation sectors by having a cooling effect on climate that lasts 30-70 years. This cooling effect results from the very high emissions of SO2 and NOx. However, the warming effect will dominate in the long term because shipping also emits significant amounts of CO2.
Neither international shipping nor international aviation is covered by the Kyoto Protocol today. Ongoing climate negotiations are debating whether one these emissions should be included in a post-Kyoto agreement.
Choice of method important
Understanding the climate impact of transportation requires not only taking into account the total quantity of emissions, but also how emissions of various components interact with one another and the climate. Transportation emits a broad mix of components with very different characteristics with respect to climate impacts. They operate on different timescales and cause both warming and cooling. Aviation emits between 2 and 3 percent of the total human-produced CO2 emissions, but that does not tell the full story. Effects down the cause-effect chain must be considered when we assess the climate impacts of this sector.
“When we quantify and compare the climate impacts of the different transport sectors, the conclusions will vary strongly depending on which method and climate indicator is used and the adopted time perspectives,” says Fuglestvedt. “In this work we have looked at the emissions’ effect on global mean temperature. This is a significant step forward compared to earlier work. In our previous study we quantified the climate impacts in terms of accumulated radiative forcing, which is similar to the Global Warming Potential (GWP) method used in the Kyoto Protocol.”
Integrated radiative forcing and GWPs give equal weight to effects over time up to the chosen time horizon.
“After 100 years, this method still gives full weight to impacts on climate that happened 99 years ago. It therefore has a ‘strong memory,’” Fuglestvedt explains. “When used on short-lived gasses and particles with strong climate effect, this characteristic of GWP can give results that are quite different from what we get when we use temperature as indicator.”
Petter Haugneland | alfa
Scientists on the road to discovering impact of urban road dust
18.01.2018 | University of Alberta
Gran Chaco: Biodiversity at High Risk
17.01.2018 | Humboldt-Universität zu Berlin
On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.
We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
19.01.2018 | Materials Sciences
19.01.2018 | Health and Medicine
19.01.2018 | Physics and Astronomy