Roads form the backbone of modern society's infrastructure. As urbanization and transportation needs increase, environmental impacts also rise, while climate change becomes an increasingly significant threat. This article examines the causes of climate change, the contributions of the transportation sector to this process, and the advantages of concrete roads in combating climate change.
What is Climate Change and Why Does It Occur?
Climate change refers to long-term alterations in global climate patterns. These changes result from both natural processes and human activities. Greenhouse gases like carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) accumulate in the atmosphere, trapping heat from the sun. This leads to rising global temperatures, melting glaciers, and rising sea levels.
Key Data:
- According to the Intergovernmental Panel on Climate Change (IPCC), human-induced greenhouse gas emissions have increased atmospheric CO2 levels by 40% since 1750.
- A study by the National Aeronautics and Space Administration (NASA) shows that global surface temperatures have risen by approximately 1 degree Celsius over the past 100 years.
Sectors Most Contributing to Climate Change
-
Energy Production: The burning of fossil fuels constitutes a significant portion of global greenhouse gas emissions. Transitioning to renewable energy sources can mitigate this issue. According to the International Energy Agency (IEA), the energy sector is responsible for about 42% of global CO2 emissions.
-
Industry: Various industrial sectors, particularly the chemical industry, emit substantial amounts of CO2. Heavy industries are known for high energy consumption and emissions. The United Nations Environment Programme (UNEP) reports that the industrial sector contributes 21% of total greenhouse gas emissions.
-
Agriculture and Deforestation: Agricultural activities and deforestation increase carbon emissions. Forests play a crucial role in climate change mitigation by absorbing large amounts of carbon. The Food and Agriculture Organization (FAO) states that deforestation accounts for 10% of global greenhouse gas emissions.
-
Transportation: Fossil fuels used in vehicles are a major source of CO2 emissions. Road transport, maritime, and aviation are significant contributors in this sector. According to the Environmental Protection Agency (EPA), the transportation sector accounts for 29% of greenhouse gas emissions in the U.S.
Impact of the Transportation Sector on Climate Change
The impact of the transportation sector on climate change can be examined in two main areas: emissions from vehicles using the transportation network and the effects of road infrastructure types, particularly in the road network.
-
Fossil Fuel Consumption: Gasoline and diesel vehicles produce large amounts of greenhouse gases. Electric vehicle alternatives can mitigate this issue. Research by the International Council on Clean Transportation (ICCT) shows that lifecycle emissions of electric vehicles are 50-70% lower compared to gasoline vehicles.
-
Road Transport: Diesel vehicles on highways have high emission values. Rail transport and electric vehicles are more sustainable alternatives. According to the European Environment Agency (EEA), rail transport produces 75% less CO2 emissions compared to road transport. However, the "door-to-door" advantage of road transport is not applicable to other modes, making the choice of road type more significant in combating climate change in the short to medium term.
Effects of Road Infrastructure on Climate Change
In addition to reducing emissions from transportation vehicles, implementing low-emission strategies in road infrastructure is crucial in reducing global carbon emissions and combating climate change.
The environmental impact of road infrastructure can be categorized into four main areas: albedo, re-carbonation, urban heat island effect, and fuel consumption.
- Albedo
Albedo refers to a surface's ability to reflect sunlight. A higher albedo value indicates more light reflection and less absorption. High albedo surfaces reflect more sunlight, reducing surrounding temperatures and energy consumption. Increasing urbanization reduces high-albedo surfaces like ice, soil, and forests, replacing them with low-albedo dark structures, which absorb more sunlight and increase temperature. A study published in Nature Communications suggests that increasing albedo in cities can reduce surface temperatures and energy consumption by up to 10%.
Concrete roads have an albedo value approximately 3-4 times higher than asphalt roads. Asphalt roads, due to their dark color, absorb more sunlight and typically have a low albedo value of around 0.10. This results in higher surface temperatures and exacerbates the urban heat island effect, accelerating global warming.
Concrete roads, with an albedo value of about 0.30 (nearly as high as ice), provide tangible benefits in reducing global carbon emissions. By reflecting more sunlight, they help lower environmental temperatures and slow global warming. For example, projections in the U.S. show that converting roads from asphalt to concrete could result in a temperature decrease of 1.2°C in Boston and 1.8°C in Phoenix, with potential reductions of 2 Mt CO2e and 9.5 Mt CO2e, respectively, over a 50-year period.
- Urban Heat Island Effect
The urban heat island effect occurs when urban structures and asphalt surfaces absorb and retain solar energy, causing higher temperatures in cities compared to rural areas. This effect is exacerbated by dense construction, reduced green spaces, and high energy consumption. The Environmental Protection Agency (EPA) reports that in some large cities, this temperature difference can reach up to 10 degrees.
Different road surface materials significantly impact the urban heat island effect. Asphalt roads, with their dark color, absorb much of the sunlight and have low albedo values, leading to higher surface temperatures and a more pronounced urban heat island effect. Considering that approximately 65-70% of city areas are covered with roads, the heat-raising impact of asphalt roads becomes more evident.
In contrast, concrete roads, with their higher albedo values, reflect more sunlight and absorb less, reducing surface temperatures and mitigating the urban heat island effect. Lower surface temperatures also decrease air conditioning usage, leading to reduced energy consumption and carbon emissions.
.png)
- Re-carbonation
Re-carbonation is the process by which concrete absorbs atmospheric CO2 over its service life, reversing the calcination reaction that occurs during cement production. During cement production, calcium carbonate is broken down, releasing CO2. However, the exposed surfaces of concrete structures absorb CO2 over time, converting calcium hydroxide into limestone. Thus, concrete structures act as carbon sinks, helping to mitigate global warming and climate change.
Re-carbonation rates increase with the surface area of concrete exposed to the atmosphere. Therefore, concrete roads, with their extensive surface area, experience higher re-carbonation rates compared to other concrete structures. Additionally, the re-carbonation process accelerates during the recycling of old concrete roads.
Studies by MIT in the U.S. show that concrete roads contribute significantly to emission reduction through re-carbonation both during their service life and recycling process. Concrete roads can capture up to 21% of the CO2 emitted during cement production through re-carbonation.
In Turkey, research indicates that approximately 20,000 km of existing concrete roads could absorb around 600,000 tons of CO2 over their 30-year service life and recycling period, reclaiming up to 19% of the emissions from cement production.
- Fuel Consumption
Another important aspect in combating climate change is the impact of road infrastructure on vehicle fuel consumption. Factors such as surface texture, smoothness, and deformation affect fuel consumption. Studies in the U.S., Canada, Sweden, and Japan show that concrete roads, due to their rigid structure, minimize deformation and therefore reduce fuel consumption.
Heavy vehicles moving on flexible pavements experience increased fuel consumption due to deformation, which is akin to moving uphill. This results in higher fuel consumption.
Concrete roads' rigid structure reduces deformation, leading to up to 7% fuel savings. On average, this translates to approximately 0.45 liters of fuel savings per 100 km per heavy vehicle and a reduction of 2.1 kg of CO2 emissions.
Conclusion
This article examined the causes of climate change, the transportation sector's contributions to this process, and the advantages of concrete roads in combating climate change. Roads play a critical role in modern infrastructure, and selecting the right road surface type can significantly impact environmental effects.
Concrete roads provide substantial benefits in combating climate change through their high albedo values, which reduce surface temperatures and mitigate the urban heat island effect. The re-carbonation process further helps in reducing atmospheric CO2. Additionally, concrete roads' rigidity results in fuel savings and reduced emissions.
In summary, concrete roads offer significant advantages in combating climate change and play a crucial role in environmental sustainability. City planners and infrastructure engineers should consider these benefits to create more sustainable and climate-friendly infrastructure.