[updated in May 2012]
Are greenhouse gas emissions from transport still on the rise in Australia? Are vehicle fuel efficiency improvements making a difference?
This post takes a look at available emissions data.
Australian Transport Emissions
The Department of Climate Change’s National Greenhouse Gas Inventory reports Australia’s emissions in great detail, and 1990 to 2010 data was available at the time of updating this post (there is usually more than a year’s lag before this data is released).
But the Department of Climate Change has recently began publishing quarterly reports that includes more recent transport figures. Here’s what the rolling 12 month trend looks like:
Transport emissions surged by 4.8% in 2011. The quarterly report attributes this growth mostly to aviation and road freight sectors.
Here’s the make up of those emissions to 2010:
In 2011 transport represented 16% of total Australian emissions (excluding land use).
Road transport contributed 86% of transport emissions (down slightly from a peak of 89% in 2004). Cars accounted for 50% of Australia’s transport emissions in 2010, but their share has been declining.
Note that the above chart does not include electric rail emissions (see below), indirect emissions, or emissions from international shipping and aviation. They are included in the following chart lifted from an 2008 ATRF paper by BITRE’s David Cosgrove shows this adds a lot on top (and the future projections are frightfully unsustainable). International transport emissions seem to sneak under the radar in the figures.
Per capita transport emissions
The following chart shows Australian transport emissions per capita have been fairly flat, with a drop in 2009 and 2010 but a resurgence in 2011:
An aside on electric rail emissions
Electric rail emissions are included under stationary energy, rather than “transport” in the main inventory. Melbourne train and tram electricity emissions have been estimated at 505 Gg for 2007 (ref page 8). Apelbaum 2006 estimated that Australia electric rail emissions in 2004/05 were 2,082 Gg (ref page 68), which is very similar to the inventory figures. I’ve struggled to find any other figures on electric rail emissions in the public domain.
Sectoral growth trends
Transport is now Australia’s second largest sector (after stationary energy), and transport has had the third highest rate of emissions growth (very close to second placed industrial processes).
Within the transport sector, civil aviation has had the strongest growth since 1990 (but note that a lot of this relates to the bounce-back from significant disruptions to domestic aviation in 1990). There’s been a lot of growth in light commercial vehicles, trucks and buses, and in more recent times, motorcycles and railways. Car emissions peaked in 2004 and have been trending downwards since.
Transport Emissions by state
The national inventory data allows us to see what is happening at a state level. As my interest is primarily in passenger transport here is a chart for road emissions:
The trends show strongest growth in Queensland and Western Australia, little growth in South Australia, and a recent decline in Victoria. It’s hard to see the trends on these charts for Tasmania and the territories due to the scale (sorry). And these growth rates will of course depend on various factors, such as economic development and population growth.
The following charts attempt to remove population growth by showing emissions per capita figures for each state (unfortunately the climate doesn’t take into account per capita (or per-GDP) emissions). Most states appear to be in decline except for Western Australia and the Northern Territory.
Car emissions reductions – mode shift or fuel efficiency?
The following chart shows car emissions per capita (which essentially removes freight from the road transport figures).
Again, all states (except WA and NT) show a decline in recent years, with stronger reductions in the states with cities showing more mode shift to public transport (refer to earlier post on BITRE data).
Is the drop in road transport emissions related to behaviour change and/or fuel/emissions efficiency?
The following chart shows that the average emissions per km of Australia cars has been trending downwards (I’ve used BITRE Working Paper 124 data on car kms travelled hence a little noise):
We’ve seen more significant declines in car emissions per capita since around 2004. So what if cars had made no improvement in emissions intensity since 2004? The following chart estimates what car emissions per capita would have been in that case:
Car emissions per capita have dropped from 2.20 to 1.87 tonnes between 2004 and 2010. It would appear that emissions efficiency improvements since 2004 can explain 0.12 tonnes of this difference – around 36% of the overall decline. This would suggest that travel behaviour change has contributed around 64% of the reduction in car emissions since 2004.
What about transport emissions in cities?
As part of the Victorian Transport Plan, the Victorian Department of Transport commissioned the Nous Group to do a wedges exercise on Victorian transport emissions. This report included estimates of Melbourne’s 2007 transport emissions (12,270 Mt). In addition, Apelbaums’s Queensland Transport Facts 2006 was for a brief time on the internet and I was lucky enough to grab a copy. From that report, estimates of Brisbane’s 2003-04 transport emissions can be derived (7,312 Mt).
The breakdowns are remarkably similar:
What does this look like per capita? I’ve also added London and Auckland figures (though I am not aware of the make up of the Auckland data) to create the following chart:
Obviously these cities’ transport systems and energy sources are very different, but it shows what is possible even for a large city like London. Transport emissions will closely follow transport energy use per capita, which has been the focus of a lot of research, particularly by Prof Peter Newman (eg his Garnaut Review submission).
For 1995 measures of passenger transport emissions per capita for other cities, see this wikipedia chart created using UITP Millenium Cities Database for 1995. Note: these figures only include passenger transport and hence are different to the above.
Also, here is some data for US cities from the Brookings Institute, but it excludes industry and non-highway transportation so is not comparable to the above chart.
Where are transport emissions headed?
The most recent data suggests that Australian transport emissions are presently on the rise.
The 2010 Department of Climate Change projections suggest transport emissions will continue to rise, as shown in the following chart lifted from their website:
Most of the forecast growth is expected to come from freight vehicles (trucks and light commercials). Curiously they forecast quite small increases in car emissions. This is based on forecast significant improvements in emissions intensity but also a return to growth in total car kms travelled (including car kms per capita).
Here is a chart of forecast of car emissions intensity, derived from their forecast data on vehicle kms and emissions:
Perhaps more optimistic is the assumption around future oil prices:
At the time of writing the oil price was $113/barrel (in April 2011 US dollars). Even with an inflation adjustment, this is certainly pushing the high end of their sensitivity testing. This prediction of oil prices doesn’t seem to take into account peak oil, or even much of an oil crunch (where supply cannot keep up with demand).