Transport & Global Overview

Greenhouse gas emissions from transport are a key contributor to the global climate crisis and air pollution.

Carbon dioxide represents the largest proportion of greenhouse emissions. Over the past three decades, emissions from transport have risen faster compared to all the other sectors and are projected to rise more rapidly in the future. Globally, transport accounted for one quarter of total emissions in 2016, 71% higher than what was seen in 1990.

Transport is a major user of energy, and burns most of the world's petroleum.

Air pollution, noise and urbanization are just a few of the many environmental damages that transport can cause. And they can happen at any stage, from production of transportation devices to the recycling.

The effects of transportation can be harmful for every species and have become a threat to humans as well. In Europe, the World Health Organization (WHO) calculated that at least 6% of premature deaths are due to air pollution.

The situation effects animals on a bigger level, since they live in over-urbanized environments, they suffer from light pollution, noise pollution and air pollution at the same time.

Different types of transportation and statistics

We know several environmental issues transport is partly responsible for, including air pollution and global warming. We know as well that more than 90%  of the worldwide population breathe polluted air and the average temperature increased by 0,8C°.

Indeed transport emits 26% of greenhouse gases emissions in Europe. But all transportation modes are not responsible at the same scale. For example, the CO2 footprint of an average airplane is 20 times larger than of a train for traveling the same distance.

The problem of this sector in terms of climate change reduction is the growth. Each year the air traffic grows between 4% and 5% which is a big number for a sector that needs to reduce its greenhouse gases emissions. It is the same for cars, they are, every year, more in numbers and contribute a lot to emissions.

Impact on the environment

Air pollution
In October 2013, the World Health Organization classified outdoor air pollution and outdoor air particles as cancerogen for humans. Air pollutants, especially particles, represent a major health issue. In Europe, it is estimated that exposure to PM 2.5 fine particles reduces life expectancy by 8.2 months. The latest scientific data strengthen the link between outdoor air pollution and respiratory and cardiovascular diseases and highlight effects on reproduction, fetal or neurological development. The impact of air pollution start to be felt everywhere on the globe, essentially with global warming that threaten the whole planet.

Indeed, pollution from exhausts is the first emitter of CO2 which is part of greenhouse gases. 13% of the total greenhouse gas emissions is due to transportation, essentially road transport.

Nitrogen dioxide (NO2) and ozone (O3) are also toxic for humans and have several effects on ecosystems. The health costs of pollution, including premature deaths, chronic bronchitis or cardiovascular diseases, represent each year between 110 and 130 billion euros in Europe. Scientists think that this number will increase in the following years and these issues would cost more than 200 billion euros for the European society.

Over-urbanization and space consumption
The consumption and fragmentation of space associated with the development of transport infrastructure (roads, rails, airports…) has a strong impact on the physical and natural environment, plants, animals, agriculture and even the quality of life for humans. The consumption of space by transport leads to the effect of isolation and thus crossing problems for individuals and wildlife. In extra-urban areas, infrastructures and associated remembrements can cut paths, diminish the tourist interest of certain zones and fragment the areas of life of the species. It is thus considered that a "fragmented" territory in ten parts sees its biological diversity divided by two.

Noise pollution
Transport is also strongly responsible for noise pollution. In Europe, 125 million people would be exposed to noise levels above 65 dBA on the façade, including around 7 million at levels above 70. The noise is mainly due to road traffic and, in a smaller scale, rail traffic and air traffic. It is considered that the noise level that corresponds to an acoustic level of comfort is 55 dBA, which would respect natural life and create better human life quality. The noise level for a quiet day in the countryside is 40 dBA, but to reach the 40 dBA objective, next to a motorway for example, you have to travel between 1 and 3 km. It is the same for several species that have a small resistance to noise.

For instance, birds need a low level of noise, to have an efficient communication. This is why they start to leave noisy areas. This displacement of animals leads to overpopulation in some places which is dangerous for food ressources and relation with predators.

Water pollution
Major road infrastructures cause changes in the aquatic environment, both surface water and groundwater. For example, the effects on watersheds. The mountain is a fragile system, subject to sudden flow regimes and easily modified. The road network can accentuate modification process of resources quality for absorption and various phenomenons, or by modifying the flows.

There are also problems associated with rainwater treatment. Rainwater can’t be absorbed in urban areas. Thus, nutrient and chemical product are brought by flows to sewers and, finally, stay in wastewater.

It leads to high flow rates in water supply networks with a diffuse pollution (metals, hydrocarbons) that can disrupt treatment in wastewater treatment plants. In non-impregnated or rural areas, this pollution affects soils, groundwater and streams.

Nitrogen oxide is one source of pollution from cars and trucks.

Pollution from cars has also impacted the quality of water, as smoke from the exhaust combines with rain, leading to acid rain, which makes its way to oceans and seas.

Let’s compare the impact and different aspects of each transportation system.

Transportation & Planes
Planes are definitely the worse transportation mode. It spends on average 285g of CO2 for each kilometer and per passenger. This number is an average because the range of energy spendings is from 150g per kilometer if the plane is full and for long distance. But it can also be worse, for instance a plane traveling with only half of its passengers and for short distance will spend a lot more energy. We estimate that airplane CO2 emissions represent 2.5% of all CO2 emissions related to humans.

Then, the problem of planes is not only based on CO2. A lot of several and harmful substances come from plane exhaust and harm environment in a high scale. For example, sulfur is a substance that has a warming power 22000 times more harmful than CO2. In the fuel used for airplanes we can find 3000 times more sulfur than in the fuel for cars. This number illustrate the lack of regulation for companies in this sector, they can use fuel which has a very dangerous impact on environment even if they pay nothing on it.

Transportation & Marine
As for planes, ships don’t have regulation in term of fuel, they can use the type of fuel they like, even with a disastrous impact. We can find in this fuel some substances that are even worse that fuel used for planes.

Ships emits sulfur oxides and nitrogen oxides in the atmosphere to form sulfate and nitrate. These gases are responsible for acid rains that harm soils and plants, but they have many other harmful effects. Emissions of nitrogen oxides, carbon monoxide, and volatile organic compounds (VOC) will lead to enhanced surface ozone formation and methane oxidation, depleting the ozone. The effect of the international ship emission on the distribution of chemical compounds like NOx, CO, O3, OH, SO2, HNO3, and sulfate is so impactful for the atmosphere. Scientists consider that 16 ships can emit as much sulfur oxides as 50 million cars.

Transportation & Road
The gases that are emitted out from the exhaust of an automobile contain various poisonous gases that are harmful for living beings. Gases like carbon-dioxide, carbon-monoxide, oxides of nitrogen exacerbate the already deteriorating ozone layer. The harmful particles that remain suspended in our atmosphere impact the quality of air that we breathe and can lead to several diseases.

Car exhausts emit several gases that are in the category of greenhouse gases, therefore participating in the global warming. Carbon dioxide, nitrogen oxides or even sulfur are spread in the atmosphere everyday due to car transportation. 13% of all greenhouse gases human emissions are made by transport and 9% are made by cars. Hopefully, car are a bit more regulated than other transportation systems. Exhausts are equipped by filters, some substances are ban from oil used for cars and speed is regulated, which is a a key element in the fight against global warming.

Transportation & Trains
Trains represent today the cleanest way to travel today. Indeed, a train, compared with other transportation mode, will use less energy for the same distance. A trains will consume 14g of CO2 per kilometer and per person, which is very low compared to planes for example, which consume 285g for the same distance. Rail’s share of transport energy consumption is less than 2% despite a market share of over 8.5%. The main polluting element of trains is the brake system which emits particles in the air. These particles are very toxic and are found all over railways. Railways themselves are also a very big issue in some regions. it can divide an ecosystem in different part, in addition to the noise disturbance made by trains and all infrastructure related to it.

Transportation & Animals
Animals are transported both nationally and internationally for slaughter and breeding. There are laws and regulations regarding animal transport to ensure animal welfare.

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Sources:

https://toxtown.nlm.nih.gov/chemicals-and-contaminants/nitrogen-oxides
https://www.epa.gov/ghgemissions/global-greenhouse-gas-emissions-data
http://www.cowspiracy.com/facts
http://www.cer.be/sites/default/files/publication/Facts%20and%20figures%202014.pdf