Plane, train, or automobile? The climate impact of transport is surprisingly complicated

Plane, train, or automobile? The climate impact of transport is surprisingly complicated

The years to come will include some major decisions regarding transport, the most polluting area. The UK government’s response to the issue to date has been inconsistent, and it has opted to intervene in order to prevent the demise of Flybe (Europe’s largest regional carrier) and to give the approval for the high-speed rail project HS2.

Decarbonizing transportation would reduce 26 percent of UK carbon dioxide emissions which result from the way people travel. But Prime Secretary Boris Johnson recently said that taking this step is a matter of ” difficult and complicated” issues. To this point, Johnson is almost certainly correct.

The protests of the gilets jaunes protests against increases in fuel duty rates in France demonstrate the delicate balance between the need for climate change action that is decisive and economic growth as well as convenience. However, shouldn’t the government let an operator of regional flights fail and invest in high-speed trains instead? The answer isn’t easy.

Carbon footprints are often misleading.

Aviation is among the most rapidly growing fossil fuel users as airlines account for around 3.5 percent of greenhouse gas emissions that are caused by humans. This may seem low; however, one transatlantic flight between London to New York can grow your personal carbon footprint by nearly the total heating expenses for the typical European.

At higher altitudes, contrails – the white lines that we can see in the sky form in the wake of aircraft. The clouds that form at higher altitudes aren’t able to reflect sunlight well. However, the ice crystals within them are able to trap heat. Contrary to the low-level cloud that has a net cooling result, these contrails are a contributor substantially to global climate change, increasing the percentage of aviation’s part carbon dioxide emissions, which is currently around 4.9 percent.

The warming effect of flights is more than their CO2 emissions by themselves. Aapsky/Shutterstock

Most of the time, the environmental benefits of high-speed rail have been taken as a given. The majority, but not all, studies suggest the possibility that high-speed rail is able to mitigate the emissions of aviation when it is able to draw sufficient passengers from other air routes. However, the climate-related impacts of aviation versus other modes of transport rely on much more than just engines and the altitude at which they travel.

It is possible to compare the emissions from different types of transportation by calculating the emission produced by each when you move one person one km. This is a way to measure the amount of CO2 released from the exhaust of each vehicle. However, it does not take into account greenhouse gas emissions resulting from the construction and maintenance of automobiles, infrastructure like runways, tracks, and airports – as well as producing fuel.

The warming effects of various greenhouse gases are experienced over various periods of time that range from only a few days of intense warming to centuries of mild influence. To create an equivalent unit for measuring the effects of various gases warming effects, they are standardized over a specific time span. The standard time frame for measuring warming effects is 100 years.

However, if it were five years later, the impact of contrails could cause the most global climate change than any of the cars on the planet. They raise the temperature of the air in short, powerful flashes. In longer time periods, such as twenty years in the future, short-term impacts are not as important and allow aviation to look more attractive – and flying possibly less harmful than other automobiles over the same distance.

The majority of comparisons focus on the emissions generated by vehicles when they’re being used. Khunkorn/Shutterstock

But this isn’t the complete story. The energy inputs required for various modes of travel differ. Direct combustion of fossil fuels by engines, such as jet kerosene used in aircraft, produces greenhouse gasses. In high-speed rails that are electrically powered, the train’s operation produces no emissions, aside from the fossil fuels used to create the electricity elsewhere.

Read more: Electric cars won’t save the planet without a clean energy overhaul – they could increase pollution

Developing HS2 will mean deploying stations, tracks, and centers of communication, and they’ll need ongoing maintenance. These all need energy and material investments, which will create further greenhouse gas emissions through manufacture, transport, and use. That could increase the carbon footprint of rail by between 1.8 and 2.5 times , over just accounting for the operation of the trains. For aviation, the same infrastructure requirements are relatively small and are responsible for a 1.2–1.3 increase, with road transport showing a 1.4–1.6 increase.

Comparing life cycle

The life cycle method provides a greater understanding of the locations of the sources of emissions and allows for the comparison of transport modes on a more comparable playing field. This helps us realize that the majority of greenhouse gas emissions that occur in transportation and air result from driving and flying, while in train travel, effects on climate are driven by the emissions generated by the construction of the infrastructure. The emissions from operating trains tend to be lower due to the dependence on electricity. However, there are emissions from the production as well as maintenance of renewable energy sources to be considered.

Each mode of high-speed travel has an environmental cost. The ability to precisely evaluate the energy needs and emissions of various transportation choices is the first step toward addressing their environmental impact.


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