Transport is affecting the climate and experts say it's only going to get worse. Data show that transport was responsible for around 10% of the total net man-made warming nearly a decade ago; topping the list was carbon dioxide (CO2) followed by tropospheric ozone (O3).
Researchers at the Oslo-based Centre for International Climate and Environment Research (CICERO) in Norway have calculated how transport will affect global warming in the coming years.
The study's results, presented in the journal Atmospheric Environment, are part of the EU-funded QUANTIFY ('Quantifying the climate impact of global and European transport systems') project, which received EUR 8.39 million under the Sixth Framework Programme (FP6).
Jan S. Fuglestvedt, director of research at CICERO, said transport emissions will treble or quadruple global warming within the next 40 years. The research team explained that based on three out of four scenarios, transport will generate 15% of the total man-made global warming in 2050. Emissions will also rise in other sectors. Right before the 22nd century kicks in, transport's contribution to man-made warming may reach 20%.
“More travelling and international trade drive the emission increase,” Dr Fuglestvedt explained. “Road transport gives the largest contribution and will most likely continue to do so in the future.”
Scientists say CO2 is the leading climate gas from road traffic. They also predict a rise in these emissions and a drop in other gas emissions.
Various gases and particles are emitted by the transport sector impacting the climate; while some emissions cool the Earth, others warm it, and some effects last for many years, while others last for only a short time.
According to the researchers, four different scenarios for emissions from transport exist, taking into account various assumptions in terms of economic development and population growth.
“A scenario-based study shows the main patterns of possible future developments, given what we know today and different assumptions,” Dr Fuglestvedt said. “We see that CO2 is the most important greenhouse gas in the long term, but several other components and effects are also important. Some of these effects are very uncertain, especially those regarding aviation.”
Ranked second in terms of highest warming effect is global aviation, and CO2, contrails and cirrus clouds play a central role in this effect. However, researchers say because these processes are more ambiguous than the CO2 effect, the climate effect from aviation is more uncertain than that from road transport. Data show that aviation could be responsible for 4% of global warming in the next 40 years.
Shipping, meanwhile, has cooled the global temperature since early 2000 because of sulphur dioxide (SO2) emissions. New rules to be put in place should reduce these emissions considerably.
As for what the future holds in terms of greener transport means, the researchers said zero-emission vehicles and new fuels will be launched on the market.
A total of 40 partners from EU Member States including the Czech Republic, Hungary, Poland and the UK, as well as Russia and the US are participating in the QUANTIFY project, which is being coordinated by Germany's Deutsches Zentrum für Luft- und Raumfahrt (DLR) and is due to end in February 2010.
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