Carbon dioxide is the most prevalent greenhouse gas and is the leading pollutant in the atmosphere, causing our Earth’s natural greenhouse effect to intensify and lead to steadily increasing atmospheric temperatures. Before our geologic age of the Anthropocene, named based on the human effects on the environment, carbon dioxide within the Earth’s carbon cycle was able to ebb and flow between natural sinks – areas that absorb carbon dioxide from the atmosphere – and sources such as methane-emitting mangroves. However, as humankind has industrialized and continued pumping out greenhouse gases, the sinks present in the environment have been unable to balance out our increasing emissions.
Ultimately, human activity has pushed the planet past its tipping point, causing various positive feedback loops that are accelerating us towards this trend of global warming., One daunting example is the melting of permafrost in the Arctic. These areas of frozen organic matter have been in a solid state for thousands of years deep within the earth. However, as global temperatures increase, this permafrost has thawed and continued to decay, releasing this organic matter, and thus sources of carbon dioxide and methane into the atmosphere. These greenhouse gases then contribute further towards atmospheric warming, continuing the cycle.
Though it might seem like a futile endeavor to cut down on these emissions now, considering the United States’ dependence on energy and transportation – the largest sources of emissions, there are still mitigation strategies that the country can pursue. However, dealing with such an issue of air pollution requires policy intervention at the federal level.
There are arguably many different solutions for our carbon emissions. The following points outline the various options that our society could pursue to work towards mitigating our emissions.
- Stop emitting
This approach is ideal, but also lofty and unattainable. In this time and age, it is difficult to even imagine living without carbon emissions. What would completely cutting emissions entail? It would mean the halting of vehicular transportation, including buses, cars, motorcycles, and trains. It would cut off electricity usage across the country, extending to services such as lighting, heating and air conditioning, and internet access. All industries would grind to a halt, particularly those that involve robotics and other technological innovations powered by electricity. The food and agriculture industry would slow, since many of the most productive farms utilize large-scale machinery to harvest crops. Though this is an impossible endeavor, it is possible at the individual level to cut down on emissions, such as biking places or handwashing laundry rather than using washing machines. At larger scales, there are policy tools that can be put in place to reduce emissions, though they can only slow the introduction of additional carbon dioxide to the environment. For example, the ENERGY STAR certification program allows consumers to use more energy efficient appliances that result in fewer emissions.
- Carbon capture and sequestration
The first step to this method is typically capturing the CO2 at the point sources of emission, using various technologies such as carbon scrubbing techniques. These techniques aim to separate the carbon dioxide from the gases that are produced in energy generation through a form of combustion. From there, the question is where to store this captured carbon safely and permanently. Some of the initiatives being taken around the world include injecting or burying the captured forms of carbon in rock formations below the surface of the earth. Other options include storing the carbon in the planet’s oceans, which already act as natural carbon sinks. Though these potential methods are viable, there are many uncertainties that arise about whether they are truly permanent or if they are any safer for the environment. Storing carbon inside rock poses the risk of gas leaks that may contaminate local water sources, and adding carbon to the ocean causes acidification as a result of chemical reactions. Additionally, with our current technological capabilities, there are tremendous costs to these capture and sequestration methods – costs arising from extracting and compressing the CO2, drilling into deep sedimentary rock beds, constructing the injection wells – that cost up to $140 per ton of CO2. The Kemper Project, which was to be the first entirely “clean coal” power plant, had racked up $7.5 billion in costs before being shut down.
- Carbon offsets
As individuals and companies set and work towards their own goals of carbon neutrality, there has arisen voluntary demand for carbon offsets, creating a marketplace in which units of carbon are removed from or prevented from entering the environment. For example, Duke’s Office of Sustainability has spearheaded a Carbon Offsets Initiative with the commitment to becoming carbon neutral by 2024, meaning the university is attempting to offset as much as it emits., The offset purchases within the market often go towards projects such as reforestation and methane destruction programs that physically work to remove the carbon dioxide from the atmosphere. In the United States, there are multiple smaller regimes that implement these offsets markets – California’s Global Warming Solutions Act of 2006, the Western Climate initiative, the Regional Greenhouse Gas Initiative, and many company-level initiatives.
The United States needs to take responsibility of its carbon emissions instead of treating the world atmosphere as a common-pool resource. As the second highest country in emissions, there needs to be action at the political level to work towards incentivizing offsets using market-based tools, and further developing research on cost-effective sequestration techniques that can be used in the future. In order to really pursue these goals of cutting down on emissions, the United States has to be willing to front the costs of offsets and sequestration in order to prepare for a more sustainable future.
 The Guardian, “What are climate change feedback loops?” https://www.theguardian.com/environment/2011/jan/05/climate-change-feedback-loops, (January 5, 2011)
 NASA, “Effects of Changing the Carbon Cycle,” https://earthobservatory.nasa.gov/features/CarbonCycle/page5.php, (June 16, 2011)
 National Snow and Ice Data Center, “Methane and Frozen Ground,” https://nsidc.org/cryosphere/frozenground/methane.html, (2019)
 Mary Hoff, “8 Ways to Sequester Carbon to Avoid Catastrophe,” https://www.ecowatch.com/carbon-sequestration-2461971411.html , (July 19, 2017)
 NAE Grand Challenges for Engineering, “Develop Carbon Sequestration Methods,” http://www.engineeringchallenges.org/challenges/sequestration.aspx, (2015)
 Michael Barnard, “Carbon Capture is Expensive Because Physics,” https://cleantechnica.com/2016/01/19/carbon-capture-expensive-physics/, (January 19, 2016)
 Sharon Kelly, “How America’s clean coal dream unraveled” https://www.theguardian.com/environment/2018/mar/02/clean-coal-america-kemper-power-plant (March 2, 2018)
 Ecosystem Marketplace, “Carbon Market: Overview,” http://www.ecosystemmarketplace.com/marketwatch/carbon/ (2019)
 Duke University Office of Sustainability, “What is a Carbon Offset?” https://sustainability.duke.edu/offsets/about/what-carbon-offset (2019)
 Union of Concerned Scientists, “Each Country’s Share of CO2 Emissions”, https://www.ucsusa.org/global-warming/science-and-impacts/science/each-countrys-share-of-co2.html (October 11, 2018)