2.2.1. Heat emissions from crude oil making
According to “the use of crude oil in plastic making contributes to global warming” (Gervet, 2007), the net generation from plastic making is overestimated. Unfortunately, it is not possible to know the amount of plastic that already burnt or decomposed. Moreover, it is not known whether to crude oil production reports consider the oil related raw material in plastic making.
The net heat generation from the use of crude oil in plastic making is roughly 0.414 kWh from 1939 – 2000. It corresponds to 1.3% of the missing heat and contributes to 0.5% of the global warming. Its contribution is about the same magnitude with the gas flaring, less than impact of nuclear power, but more than coal fires. The contribution of plastic production and disposal to climate
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change has been largely hidden which estimates the GHGs footprint of plastic from the cradle to the grave for the first time (Center for International Environmental Law, 2019).
After the extraction of fossil fuels to produce plastic, the carbon footprint of a material which has become ubiquitous across the globe continues through the refining process, and on well past its useful life as a drinks bottle or plastic bag, through the way it is disposed of and the plastic afterlife, most of plastic items sustain for more than 200 years in the environment prior to decay so most of them are dumped into landfill.
2.2.2. Greenhouse gases emission from plastic waste treatment
As mentioned before, plastic products contribute directly or indirectly to greenhouse gas emissions, from production to refining and transport. The effects of plastic products on the climate do not end when they are thrown away. They will continue to be a climate threat through the disposal of plastic waste such as recycling, landfill, incineration, and an amount of waste that is freely dumped into the environment. Among these types of disposable packaging, plastic packing is one of the types that cause the most problems because of the unique, disposable packaging characteristics. Therefore, plastic packing accounts for 40% of the total waste.
According to the report published by Center for International Environmental Law (CIEL) about the hidden climate polluter from plastic incineration, plastic packaging burns an additional 16 million tons of GHG into the atmosphere at a global level. This is equivalent to more than 2.7 million households using electricity every year. If the petrochemical industry expands by 2050, GHG emissions from burning plastic packaging will increase to 309 million tons. These estimates only account for plastic packaging, which
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accounts for 40% of total plastic waste and 64% of plastic packaging waste is managed after use. This is just over a quarter of plastic waste. Therefore, the potential for much bigger climate impacts still comes to rest.
Plastic waste is still increasing, and greenhouse gas emissions from plastic waste incineration have also increased despite the urgency of addressing plastic pollution and climate change by reducing plastic use and burning.
The quantity of gases emitted from dumping grounds and landfill sites depends considerably on the air temperature and climatic season. It increases when the temperature is high and the emission quantity in summer is higher than in winter. It is estimated that in the degradation process of garbage, 30%
of the gas emission from landfill sites can lead to the ground surface without any intervention Greenhouse effect due to the emission of CH4 and CO2.
Burning waste produces carbon dioxide and smoke containing particles harmful to health, but smoke also contains small black particles that have a significant impact on the climate in the short term. The amount of soot is maximized when the garbage contains two types of plastic: polystyrene and polyethylene terephthalate (commonly abbreviated as PET, commonly used in the manufacture of beverage bottles). When burning waste containing fiber, many of which are plastic and soot emissions rise (Natalia et al, 2019).
Black carbon from burning open waste has an effect of global warming equivalent to 2% to 10% of global carbon dioxide emissions. If this situation does not change, this problem is set to get worse as the amount of waste we throw away is expected to increase by 70% by 2050.
Compared to other plastics and organic wastes, large carbon black emission factors are observed, especially with PET and polystyrene, which means these resins are a major source of overall black carbon (Natalia et al, 2019).
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2.2.3. Greenhouse gases emission from plastic
In 2018, a study from Hawaii University led by Sarah - Jeanne Royer showed that the increasing accumulation of plastics in the environment contributes to climate change. These effects are the result of plastic exposure to solar radiation in a decaying or degrading environment. The study also shows that of the most commonly used plastics worldwide, LDPE, the most abundant plastic found in the ocean, releases methane, ethylene, ethane and propylene at the highest levels. Another finding suggests that the larger the surface area of the plastic, the greater the release of greenhouse gases.
For example, sanitized LDPE produces methane up to 488 times faster than pellet form at the same weight.
The study has proven that plastics exposed to sunlight produce more gas.
LDPE releases about twice as much methane and 76 times as much ethylene when exposed to air than when incubated in water. As such, the plastic floating on the ocean surface and the plastic on the shallow environment emit greenhouse gases even though it has not been mentioned.
After a period of survival in the environment, the plastic exposed to environmental conditions such as temperature, light, and moisture will begin to weaken, often becoming brittle and breaking into small pieces. In water like the ocean, biodegradation, oxidative degradation, thermal degradation, hydrolysis and solar radiation contribute to greenhouse gas production.
This finding suggests that a large amount of greenhouse gases from plastic waste has not been shown in the past. And that amount of greenhouse gases tends to increase as the amount of plastic and plastic thrown into the environment still increases every year (Andrady, 2011).
17 2.2.4. Impact on the oceanic carbon sink
The ocean becomes the largest reservoir of greenhouse gases to absorb greenhouse gases. It absorbed 30% to 50% of the total CO2 from the industrial era in the late 18th century. The problem of plastic waste in the ocean emitting greenhouse gases has been mentioned in many studies. However, in addition to those direct effects, a recent study also pointed out that the indirect impact of plastic waste on the ocean affects climate change through its impact on the activities of living organisms like Plankton, what brings carbon to the bottom of the ocean (Tim de Vries et al., 2017).
Plankton in the ocean includes phytoplankton and zooplankton. They all play different roles but are related to the absorption of CO2 and transport to the ocean floor. Phytoplankton is capable of photosynthesis absorbing nearly half of the atmospheric CO2. Not only does it play a role in producing the first food chain for the ocean, plankton also contributes to 80% of the world's total oxygen (Sarah Witman, 2017).
However, recent laboratory studies have shown that micro-plastic in water can harm to Plankton. The smaller the micro-plastic size, the greater the potential for harm. This directly affects their ability to absorb CO2 and produce oxygen. Laboratory experiments have shown that the phytoplankton are poisoned by micro-plastic, reducing CO2 absorption by up to 45%. The research proves that phytoplankton easily integrate and form aggregates with microflora particles when they are in water (Gallo et al., 2018)
In addition to harm and adversely affect the uptake of carbon on the ocean surface by phytoplankton, plastic also harms zooplankton and transports carbon to the ocean floor. One can imagine phytoplankton as a carbon
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fixture, while zooplankton will play a role in transporting deep into the ocean. Without this activity, the CO2 absorbed by phytoplankton would quickly be released back to the surface of the water and into the atmosphere.
Figure below illustrates the role of plankton in carbon exchange between atmosphere and ocean.
Figure 2.3: Plankton processes (Andrew Brierly, 2017)
However, the presence of micro-plastic in the ocean has caused the zooplanktons to confuse it as food. When zooplanktons are contaminated with micro-plastic, its ability to absorb phytoplankton decreases by 40%. Next, the
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consequence of plastic poisoning is that the eggs of the zooplankton become smaller, with a higher mortality rate (Cole et al., 2016).
In the study of Cole et al., also indicated that, when zooplankton eat phytoplankton, the carbon they absorb is transported to the deep sea in pellet form. The pellets slowly fall into the deep sea, where it settles into the mud on the sea floor. Studies show that microorganisms are transported below the surface of the plankton. However, if the pellets are contaminated with particles, they will sink slowly and break more easily. Therefore, the function of transporting carbon into the deep sea of plankton is greatly affected.