The Global Acceptance for Anthropogenic GHGs
An introduction into the global acceptance for anthropogenic GHGs and a highlight of three major environmental topics; environmental impacts of meat production, transport emissions and plastic pollution – maritime health.
The United Nations Framework Convention on Climate Change (UNFCCC) was adopted at the Rio Earth Summit of 1992. It sets out the first overall framework intended to stabilize atmospheric concentrations of greenhouse gases (GHGs) and to “prevent dangerous anthropogenic interference with the climate system.” . The Rio Summit was followed by a series of semi-successful conferences such as Kyoto, Montreal, Copenhagen and Durban, aiming to implement action. Failure to address differences in decarbonizing capabilities between more economically developed nations and developing nations led to friction and regressive action on climate mitigation. The Paris conference of 2015 aimed to address these issues.
COP21 shifted emphasis towards national action and had a much more nuanced differentiation between developed and developing countries. It further recognized the difference in economic and resource-dependent capabilities of developed and developing nations, by placing greater recognition on adaptation and the inclusion of loss and damage. New developments on finance, such as stronger reporting provisions, renewed recognition of market mechanisms and 5-year global stock taking aimed to improve and better monitor climate adaptation. Paris also added ‘global peaking’ and balance between emissions and removals as supplementary goals.
The most ambitious target that emerged from COP21 however was the pledge to keep global temperature rise to below 2°C (of pre-industrial levels) and going further to reference 1.5°C. Global atmospheric temperature targets would encourage greater cooperation between nations as there would be a mutual target regardless of borders. These reasons founded on self-determined emissions targets and mitigation strategies resulted in the largest global agreement with 174 countries signing and more joining in the years following.
Global Greenhouse Gas Emissions
Environmental Impacts of Meat Production
There is increasing evidence that meat production, intensive or non-intensive, has been found to have a variety of negative effects on the environment due to the combination of land use and animal waste production. Agriculture accounts for 12% of global greenhouse gas emissions, while land use and deforestation accounts for another 12% (IPCC, 2014). The UN Food and Agriculture Organization reported that the livestock sector (most of which are cows) generates 18% of all global GHGs (UNFAO, 2006). This makes it the second highest source of greenhouse gas emissions (fig. 1) and more polluting than all transport emissions combined. It also consumes about 70% of agricultural land and is one of the leading causes of deforestation, biodiversity loss and water pollution.
Livestock and their by-products account for at least 32,000 million tons of carbon dioxide (CO2) per year, or 51% of all worldwide greenhouse gas emissions (Goodland and Anhang, 2009). Livestock is the greatest contributor of atmospheric methane (CH4) gas emissions, the second most potent greenhouse gas. It is 120x more powerful in trapping heat at the surface of the planet than CO2 in its first year of release; making it the biggest contributor to short-term climate change. Over a 20-year lifetime, methane is 25-100 times more destructive and has a warming potential 86 times greater than CO2 (Shindell et al., 2009).
Methane takes longer to break down in the Earth’s atmosphere than CO2 does because the breakdown of CH4 results in a series of complex feedback loops. The predominant mechanism for methane removal from the atmosphere is by oxidation with a hydroxyl radical (OH). Reactions eventually convert methane into carbon dioxide and water (H2O). However, during this process, other species such as carbon monoxide (CO), nitrogen dioxide (NO2) and hydroperoxide (HO2) can also be produced (Jardine et al., 2004). These species, along with volatile organic compounds, also react (readily) with hydroxyl radicals, meaning there are fewer available OH molecules to remove methane thus increasing its breakdown period.
Livestock covers 45% of the Earth’s total land and is the leading cause of desertification and rainforest destruction (Hogan et al., 2010; Thornton et al., 2011; Butler, 2012). The land required to feed 1 meat eater for 1 year is 3 acres, whereas a vegan or a vegetarian would require 1/6th and ½ an acre respectively (Eshel et al., 2014). World Population grows by 228,000 people every day (Worldometers, 2019) and the demand for food will follow. Emissions from agriculture are subsequently forecast to increase by 80% come 2050 (Tilman and Clark, 2014). Therefore, to reduce anthropogenic climate change, food emissions and land use – there needs to be a greater emphasis on plant-based diets.
Transport accounts for 14% of global greenhouse gas emissions (IPCC, 2014); about one-fifth of the EU’s total emissions and around a quarter of all UK GHG emissions. Although the transport sector comprises of many different mediums (aviation, maritime, rail etc.), road transport is by far the greatest emitter, accounting for more than 70% of all transport emissions (EC, 2016).
Road transport is responsible for significant contributions of Carbon Dioxide (CO2), Hydrocarbons (HCs), Nitrogen Oxides (NOx), Particulate Matter (PM) and Carbon Monoxide (CO) emissions. CO2 is the main bi-product of fuel combustion in vehicle engines. HCs are a bi-product of incomplete or partial combustion and they, along with VOCs (Volatile Organic Compounds) contribute to the formation of ground-level ozone and photochemical smog in the atmosphere which are harmful to human health.
NOx emissions, (often Nitrogen Oxide (NO) and Nitrogen Dioxide (NO2)) lead to the formation of secondary PM and ground level ozone in the atmosphere as well as contributing to acidification and eutrophication of waters and soils. PM is one of the most destructive pollutants to human health as it has the potential to penetrate through sensitive regions of the respiratory system. PM is a product of incomplete combustion and is categorized into primary and secondary PM, with the first being emitted directly into the atmosphere and the latter being formed in the atmosphere via precursor gases; SO2 (Sulphur Dioxide), NOx, NH3 (Ammonia) and some VOCs.
Finally, CO is produced from incomplete carbon combustion whereby the fuels is only partially oxidized; creating a single oxygen bond rather than two (dioxide; CO2). In humans and animals, CO prohibits oxygen from being absorbed into hemoglobin in red-blood cells while also contributing to ground level ozone and smog formation.
Figure 3: Share of transport greenhouse gas emissions in the European Union (EEA, 2018)
A combination of policies and measures introduced in the last 25 years such as; setting technological standards for vehicle emissions and fuel quality, legislation establishing air quality limits and measures implemented at the local level to manage transport use (improved planning and public transport incentives) have been successful in limiting exhaust emissions per vehicle. However, the number of vehicles on the road continues to grow annually, significantly adding to the sectors overall ghg emissions contributions.
The need to improve fuel efficiencies and the introduction of progressively stricter emissions standards have greatly contributed to technological development in the vehicle manufacturing industry. Innovations include improvements in conventional engine and exhaust technologies, eco-innovations and the development of hybrid-electric and pure-electric vehicle technologies.
In a conventional ICE vehicle, only about 18-25% of the energy available from fuel is used for movement, the rest of the energy is lost to engine and drivetrain inefficiencies (fig. 4). Improvements such as direct fuel injection, variable valve timing and lift, cylinder deactivation, turbocharging and start-stop systems are a few of the major advancements in modern vehicles combatting energy loss. Fundamentally, improvements orientate around creating optimal air-fuel compositions within the engines chamber so that the correct amount of fuel is being burned in relation to the vehicle’s application, minimizing partial or incomplete combustion.
Despite this, engines-alone still produce waste emissions that exceed government set emissions targets. Therefore additional exhaust aftertreatment technologies, such as catalytic converters, filters, traps and absorbers are used. These convert harmful particulates and gases such as NOx, CO and HCs into CO2, water and nitrogen by activating oxidation or reduction reactions through closed loop re-combustion or in the exhaust system before atmospheric release.
Hybrid vehicles have the potential to reduce fuel consumption and CO2 emissions by up to 35% (ICCT, 2015). They achieve this by powering the vehicle with an electric motor during low speed travel; in traffic, during idling or acceleration. This minimizes emissions from incomplete or partial combustion as the engine chamber is only engaged during optimal combustion periods. Pure electric vehicles on the other hand have an efficiency that may exceed 80%. They emit no waste therefore no ghg emissions, and have far fewer internal components.
Figure 4: Conversion of energy in an internal combustion engine displaying losses of efficiency (EEA, 2015).
It is becoming clear that incremental improvements in vehicle efficiencies will not deliver the substantial greenhouse gas emission reductions needed to comply with the 2°C atmospheric temperature limit. Research and policy that encourages the development and uptake of future clean technologies; ULEVs and their infrastructure, will be fundamental for the reduction in transport emissions.
Plastic Pollution – Maritime Health
1 million plastic bottles are bought around the world every minute, that adds up to approximately 500 billion bottles every year (Laville and Taylor, 2017). 2 million plastic bags are used every minute, and between 500 billion and 1 trillion plastic bags are used worldwide annually. Plastic bags are used for an average of 12 minutes and take up to a thousand years to decompose (Leblanc, 2018). 50% of all plastic used is used just once and then thrown away. Enough plastic is thrown away each year to circle the Earth 4 times over. Only 5% of plastic produced is recovered and it takes around 500 to 1,000 years for plastic to degrade (EcoWatch, 2014) with some products such as Styrofoam not degrading naturally at all (Leblanc, 2018).
Microplastics are defined as all forms of plastics less than 5mm. They can enter the oceans as primary microplastics and secondary microplastics. Primary microplastics include; beads from personal care products, microfibers from clothes and pre-production pellets (nurdles/mermaid tears) (Boucher and Friot, 2017). Secondary microplastics are derived from larger plastic items which slowly get broken into smaller pieces (Efimova et al., 2018). Weathering degradation of plastics results in surface embrittlement and microcracking resulting in the formation of microparticles (Andrady, 2011), if on the beach these particles can be carried into the ocean by wind or wave action.
Microplastics can adversely affect growth and reproduction as they can adsorb waterborne contaminants and/or leach toxic additives (Cole et al., 2011). These include organic micropollutants such as nonylphenols, an endocrine disruptor and secondary pollutants such as Polychlorinated biphenyls (PCBs) and Dichlorodiphenyldichloroethylenes (DDEs) (Marine Conservation Society, 2019). These toxins could potentially be passed into animal tissue and up the food chain as they can be ingested by everything. From primary consumers such as zooplankton to fish, seabirds, turtles and whales, eventually making their way into human ingestion.
Billions of pounds of plastic can be found in swirling convergences in the oceans making up about 40 percent of the world’s ocean surfaces. 8 million tons of plastic are dumped into the sea every year and 73% of all beach litter is plastic (National Geographic, 2018).
Figure 5: Number and weight of plastic pieces globally afloat at sea (McCarthy, 2017)
According to research conducted by the World Economic Forum; just 10 rivers are responsible for 90% of the planet’s oceanic plastic waste. Eight of these rivers are in Asia: the Yangtze, Indus, Yellow, Hai He, Ganges, Pearl, Amur, and Mekong. Two of the rivers can be found in Africa: the Nile and the Niger (Gray, 2018).
Plastic by ingestion is killing an estimated 1 million marine birds and 100,000 marine animals each year. More than 90% of all birds and fish are believed to have plastic particles in their stomach. Close to 700 species of marine life are facing extinction due to the increase of plastic pollution (Thompson, 2017). The average human eats 70,000 microplastics each year equating to about 100 bits of microplastic over the course of just one meal (Catarino et al., 2018).
However, the plastic problem can be fixed. It requires mobility from policy makers and the public to reduce our plastic dependency, increase producer responsibility, raise awareness on user discomfort, recycle properly and avoid single use and microbead plastics (Hutchinson, 2017). Raising fees and taxes on plastic pollution, stricter international cooperation and greater emphasis on circular economic models (Minter, 2018; EC, 2015). Improved funding for clean-up initiatives, waste management where the problem is greatest and stopping the flow from anthropogenic sources to sea (Jensen, 2018). Greater research, surveillance and mapping (Zabala, 2018) is also vital to improve removal processes as well as studying the effects plastic has had, is having and will have on the planet.
Written by Ajeet Panesar, Sustainable Infrastructure Specialist, Solisco