April 22, 2014

Earth Day 2014: Following the carbon footprint to the sea

by Bonnie Denmark

Where are we now, 43 years after the first nationwide Earth Day was celebrated in the US? The Intergovernmental Panel on Climate Change (IPCC) paints a grim picture in its latest assessment report, AR5, announcing that global emissions of greenhouse gases are endangering worldwide security of food, water resources, human health, ecosystems, and the economy – and humans are to blame. Carbon dioxide makes up the vast majority of US greenhouse gas emissions at 82%, most of which results from electricity production (38%), transportation (32%), and industry (14%), according to 2012 EPA estimates.

US Greenhouse Gas Emissions in 2012 (Source: EPA)

US Greenhouse Gas Emissions in 2012 (Source: EPA)

Although greenhouse gases are necessary to keep Earth warm enough to sustain life, their ability to trap heat poses a danger when released into the atmosphere in large quantities. In 2010, New York City alone added more than 54 million metric tons of CO2 to the atmosphere – nearly 2 metric tons every second. Watch Carbon Visuals’ rendering of CO2 emissions in New York City over one hour, one day, and one year. On a positive note, New York City’s emissions in 2010 were 12% less than those measured in 2005. However, globally, emissions of greenhouse gases from human activities have continued to rise (IPCC).

The atmosphere is not the only place affected by an increase in carbon dioxide levels. High concentrations of CO2 are also seen in the ocean, resulting in ocean acidification. As levels of CO2 rise in the atmosphere, CO2 levels rise in the ocean as well, causing chemical reactions which decrease the pH of the seawater. In fact, surface ocean waters have become approximately 30 percent more acidic (= lower pH) since the beginning of the Industrial Revolution (NOAA).

This graph shows the correlation between rising levels of carbon dioxide (CO2) in the atmosphere at Mauna Loa with rising CO2 levels in the nearby ocean at Station Aloha. As more CO2 accumulates in the ocean, the pH of the ocean decreases. (Modified after R.A. Feely, Bulletin of the American Meteorological Society, July 2008)

This graph shows the correlation between rising levels of carbon dioxide (CO2) in the atmosphere at Mauna Loa with rising CO2 levels in the nearby ocean at Station Aloha. As more CO2 accumulates in the ocean, the pH of the ocean decreases. (Modified after R.A. Feely, Bulletin of the American Meteorological Society, July 2008)

More underwater carbon dioxide means less oxygen for sea creatures to breathe. CO2 levels also affect how light and sound travel through the ocean, with potential impacts on marine species’ habitats and marine mammal communication.

A more acidic environment has a profound effect on coral reefs and other species that depend on calcification. Carbon dioxide (CO2) in the ocean reacts with water molecules (H2O) and carbonate ions (CO32-) to form bicarbonate ions (HCO3). (See our module for an explanation of how Chemical Equations work.) This chemical reaction reduces the availability of calcium carbonate minerals that sea creatures need to grow and maintain their shells.

Seawater carbonate chemistry (Source: NOAA)

Seawater carbonate chemistry (Source: NOAA)

The ocean must sustain not only underwater life, but the more than one billion people across the globe who rely on food from the ocean as their main source of protein. “When shelled organisms are at risk, the entire food web may also be at risk,” according to NOAA.

As with many other environmental problems we are facing, slowing or stopping ocean acidification will ultimately depend on reducing CO2 emissions. The most effective way to reduce carbon dioxide (CO2) emissions is to reduce fossil fuel consumption. This can involve

  • Lifestyle changes: Buying longer-lasting products, changing dietary habits, and reducing food waste.
  • Energy conservation: Reducing household and business energy use by turning off lights and electronics when not in use and reducing driving distances.
  • Recycling: Making products from recycled or renewable, rather than raw, materials.
  • Land management: Managing forests and implementing sustainable agriculture practices.
  • Energy efficiency: Developing and using energy efficient technologies, improving building insulation, and using fuel-efficient vehicles and energy-efficient appliances.
  • Alternate technologies: Pursuing renewable energy technologies such as wind, hydro, and solar power and developing new techniques for carbon capture and sequestration.

What’s your carbon footprint? Use the EPA’s Household Carbon Footprint Calculator to estimate your greenhouse gas emissions.

 

LEARN MORE

Learn more about the effects of carbon dioxide on our oceans in Oceanography, the official magazine of the Oceanography Society.

Visit EPA’s ActOnClimate Today for tips on how you can reduce carbon dioxide pollution.

Written by

Bonnie Denmark holds an MA in linguistics and teacher certification in English, ESL, and Spanish. She has devoted her professional life to educational and accessibility issues as a computational linguist, multimedia curriculum developer, educator, and writer. She has also worked nationally and internationally as a language instructor, educational technology consultant, and teacher trainer. Bonnie joined the Visionlearning team as a literacy specialist in 2011, assisting the project by developing comprehension aids for science modules and creating other STEM learning materials.