Laxenburg, Austria – The study, published in the journal ‘Environmental Science & Technology’ by a team of researchers from Austria and Norway, compares the impacts on global warming of different means of transport. The researchers use, for the first time, a suite of climate chemistry models to consider the climate effects of all long- and short-lived gases, aerosols and cloud effects, not just carbon dioxide, resulting from transport worldwide.
In the long run, the global temperature increase from a car trip will on average be higher than from a plane journey of the same distance. However, in the first years after the journey, air travel increases global temperatures four times more than car travel. Passenger trains and buses cause four to five times less impact than automobile travel for every kilometer a passenger travels. The findings prove robust despite the scientific uncertainties in understanding the earth’s climate system.
“As planes fly at high altitudes, their impact on ozone and clouds is disproportionately high, though short lived. Although the exact magnitude is uncertain, the net effect is a strong, short-term, temperature increase,” explains IIASA’s Dr. Jens Borken-Kleefeld, lead author of the study. “Car travel emits more carbon dioxide than air travel per passenger kilometer. As carbon dioxide remains in the atmosphere longer than the other gases, cars have a more harmful impact on climate change in the long term.”
The research also showed that when it comes to freight transport, moving goods by planes will increase global temperatures between 7 to 35 times more than moving the same goods the same distance in an average truck. Shipping, on the contrary, exerts 25 times less warming in the long run, and even cools on shorter time scales.
“Ships contribute to global warming through carbon dioxide, ozone and soot. Currently, they also emit relatively large amounts of sulfur dioxide which forms sulfate particles in the atmosphere. Those particles cool the planet by reflecting solar radiation back into space,” says co-author Dr. Jan Fuglestvedt from CICERO. “In the first decades after a shipment, the cooling effect more than offsets the warming. And because of the large volumes of goods traded by ship, global trade actually counteracts some of the temperature increases caused by global passenger travel. However, in the long term all means of motorized transport add to global warming.”
The study concluded that as climate change acts at various time scales, it is important to have policies to reduce both the air pollutants that have strong, short-term impacts and the long-lived gases that lead to long-term warming. In addition, Dr. Borken-Kleefeld argues, “A comprehensive strategy to tackle climate change caused by the transport sector is actually to minimize the demand for transport.”
A comparison of how cargo transport by different modes affects global mean temperatures five, twenty, and fifty years after the shipment. For ease of comparison truck transport has been given values of 100. Negative values mean cooling, positive values warming.
A comparison of how passenger travel by different modes affects mean global temperatures five, twenty, and fifty years after the journey. For ease of comparison car travel has been given values of 100. Negative values mean cooling, positive values warming.
Original Work:
Title of the Study: “Specific Climate Impact of Passenger and Freight Transport”
Authors: Jens Borken-Kleefeld, Terje Berntsen and Jan Fuglestvedt
Published in ‘Environmental Science & Technology’ 2010, 44 (15), pp 5700–5706, doi: 10.1021/es9039693
Click here to read the Full Study: http://pubs.acs.org/doi/abs/10.1021/es9039693
About IIASA
IIASA (International Institute for Applied Systems Analysis) is an international scientific institute that conducts research into the critical issues of global environmental, economic, technological, and social change that we face in the twenty-first century. Their findings provide valuable options to policy makers to shape the future of the changing world. IIASA is independent and funded by scientific institutions in Africa, the Americas, Asia and Europe. For more information, visit www.iiasa.ac.at.
About CICERO
The Norwegian government established CICERO (the Center for International Climate and Environmental Research – Oslo) by royal decree in 1990. CICERO is an independent research center associated with the University of Oslo. CICERO conducts research on and provides information and expert advice about national and international issues related to climate change and climate policy.
More about CICERO can be found at www.cicero.uio.no.
Source: IIASA Press Release dated August 4, 2010.
