Journey's End I

Planes, trains and automobiles, we've covered them all and before we move any further forward in our journey, I want to look back at where we have come from and the places visited. 

3 and a half months ago I embarked on a project to learn and blog about the effects travel and transport (T&T) have had, and are having, on global environmental change. Given the broad nature of the topic it is unsurprising I don't feel it has all been covered. In saying that, however, by investigating the ways in which the effects of T&T can be monitored and explored, the role of migrations to America and the Crusades in the location of the Anthropocene, the impact of cars, ships and planes in environmental change, and the ways in which the issues that have surfaced could be mitigated, we have certainly given it a good go.

While based primarily around tourism, a comprehensive 2002 article by Gossling provided the backbone for many of the early blogs, by listing three ways in which the effects of T&T could be measured; land cover and use changes, energy use and the extinction of wild species. 

Given that a number of studies that I reviewed have based their work solely or almost entirely around energy use, it was this measure I found most to write about. While this focus could have been seen as a limitation of the studies, it allowed authors to concentrate their efforts and produce some quite staggering statistics. For example, since the 1960s air travel has been growing at a rate of 9% per annum, with each passenger now using on average 2.75 mega joules per passenger per kilometre while flying, relative to the 1.44 MJ/PKM on a train or 0.75 MJ/PKM on a bus (Becken et. al, 2003). As was shown in 2 blogs about sea transport, these numbers are not confined to air travel either as in 2003 ocean going ships use 200 million tonnes of fuel each year, a figure up 53 million tonnes from 4 years previous (Endresen et. al, 2003; Corbett et. al, 1999).

While land use change as a result of T&T was more difficult to show, in saying that, however, two good maps highlighting land dedicated to roads and airports are presented, my investigation of species extinction led to the surfacing of some of the blogs most interesting ideas. Looking specifically at the ways in which habitat fragmentation and the translocation of species as a result of T&T could lead to extinctions it became clear the impact was much greater than I expected. Focussing on the latter, through the growth of trade and increases in transport efficiency the number of invasive species has been growing rapidly since 1850, and in the last 150 years the number of invasive invertebrates taxa per annum has increased from under 2 million to almost 14 (Hulme, 2009). This prompted Hulme, in his 2009 study to suggest we have entered the "3rd age of biological invasions: the era of globalisation" (Pg. 11) a claim he backs up persuasively with a wide range of evidence ranging from trends in global shipping cargo, to the relationship between gross domestic product and alien plant richness, fig. 1.

Figure 1. Here the relationship between GDP and the number of alien plant species is graphed.  It is interesting to note that the relationship is stronger between the variables for island states than for continental ones. This is most probably owing to the greater proportion of merchandise imports for island states, and the greater chance therefore of alien species.

The revelation of statistics such as these prompted me to curtail my work on the impact of travel, and instead focussed my attention over the last few weeks on the ways in which these alarming trends could be halted especially with regards to car and plane usage. While arguments that promote research into more sustainable and environmentally friendly vehicles are widespread (Mildenberger and Khare, 2000), there seems also to be a belief that such changes alone will not be enough to halt the rise in emissions. Instead many argue it is necessary to change the behaviour of car and plane users (Beirao and Cabral, 2007). Although, as illustrated, there are different ways of doing this, in my opinion the idea as a whole seems to be the one that warrants pursuing and further research. While people may not want to change their habits and make compromises at first (Hares et. al, 2010), it is the long-term option and once behaviours are changed they will be passed down through generations. It is important to recognise, however, that these changes alone, will not be enough and if there is not continued support given to research into, and the development of, more sustainable forms of transport, I would argue that emissions might plateau, but not decrease.

To finish off next time, I will be putting forward the 4 ideas I think that are vital to take from this blog.