PrintTransportation emissions have historically been the second-biggest sector for most countries (or other geographic scales of measurement), coming in only behind stationary energy sources. But, as the energy sector makes consistent strides in efficiency, these scales are tilting. Look at 2016 in the next image. Transportation emissions overtake emissions from electric power generation.
- Want to read more about this? Check out Yale Environment 360's Transportation Replaces Power in US as Top Source of CO2 Emissions from December 2017.
CO2 emissions from historical and projected energy consumption by the transportation sector in the next image shows a five-fold increase in emissions between 1970 and 2050. Emissions growth from sea transport is relatively small, whereas air and road transport increases are bigger with the highest growth rates projected for air transport. However, despite the higher growth rates, road transport still maintains the vast majority of transportation-related emissions and therefore represents the biggest opportunities for reductions.
The image is a line chart described in text below. Numbers are approximate
- Road Sector
- Historical data from IEA (1970 - 2000), increase from 1.5 Gt CO2 to 4.5 Gt CO2
- Estimated data from (WBCSD) (2000 - 2050), increase from 4.5 Gt CO2 to 8 Gt CO2
- Air Sector
- Historical data from IEA (1970 - 2000), increase from 1.75 Gt CO2 to 4.75 Gt CO2
- Estimated data from (WBCSD) (2000 - 2050), increase from 4.75 Gt CO2 to 11 Gt CO2
- Sea Sector
- Historical data from IEA (1970 - 2000), increase from 2 Gt CO2 to 5.25 Gt CO2
- Estimated data from (WBCSD) (2000 - 2050), increase from 5.25 Gt CO2 to 12 Gt CO2
The US EIA finds that energy-related CO2 emissions in the transportation sector will remain relatively constant after 2030 because of little change in the carbon intensity of transportation fuels (EIA Annual Energy Outlook 2017).
- But what about the rapidly developing economies of the world?
Projections of energy consumption (Figure 5.3) suggest that China will not be alone in its dash to institute private car ownership. Experts project that energy consumed for transport will more than double between 2000 and 2050. The strongest growth is expected to take place in the air, freight trucks, and light-duty vehicles (LDVs), which includes cars, pickup trucks, minivans, and sport utility vehicles (SUVs). That growth will be greatest in the developing countries, especially China, India, other areas of Asia, and Latin America. Note that this projection drastically underestimated the growth in China during the first decade of the millennium.
Focusing on LDVs in the next image, projections for the total stock see a doubling of LDVs in the 2020s and tripling of this vehicle type by mid-century. The least growth is projected to take place in developed countries, while robust increases are expected in developing countries. The biggest increases are projected for China, but those increases are happening now, so growth may be slower for that country later in the century.
Vehicle ownership is a function of per capita income: as income goes up, rates of car ownership increase (Figure 5.5). The wealthiest major country –– the United States –– has much higher ownership rates than any other nation. Vehicle ownership is still very high among the next richest countries, essentially Canada, western and northern Europe, Japan, Australia, and New Zealand. Next comes southern and eastern Europe and Korea, followed by other developing countries around the world.
The take-home message from this series of graphs is that global energy consumption and GHG emissions from transport are increasing rapidly and are expected to continue grow significantly in the future. The largest subsector responsible for this growth is personal vehicles, which is projected to grow strongly over the coming decades as nations and their people emerge from poverty and are able to afford ownership.
The material for this section comes from Kahn Ribeiro, S., S. Kobayashi, M. Beuthe, J. Gasca, D. Greene, D. S. Lee, Y. Muromachi, P. J. Newton, S. Plotkin, D. Sperling, R. Wit, P. J. Zhou, 2007: Transport and its infrastructure. In Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds.), Cambridge University Press, Cambridge and New York.