Environmental Visualizations That Have Changed Our World

This post was co-written by Breanna Lujan, a soon-to-be Environmental Studies graduate of Yale College. She is a Researcher for the Environmental Performance Index project at the Yale Center for Environmental Law and Policy. She will spend the upcoming year in Brazil on a Fox Fellowship.

A picture is worth a thousand words. Nowhere is this statement more pertinent than the environmental movement, which has relied on data presentations, iconic images, and visuals to provide definition and reality to some of the world's most significant and influential phenomena. The visualizations described below -- and presented in the infographic -- signify striking environmental data presentations and images that have left, and continue to leave, an indelible mark on our planet.

1) The Keeling Curve
Initiated at the Mauna Loa Observatory in Hawaii in 1958, the Keeling Curve represents the world's longest unbroken record of heat-trapping, atmospheric CO2 levels. It demonstrates concrete, long-term evidence of the increase of atmospheric carbon dioxide (CO2), the primary greenhouse gas contributing to global warming. This past April, CO2 levels reached 400 ppm -- a worrisome milestone that is nearly 50 percent higher than pre-industrial levels. The United Nations' Intergovernmental Panel on Climate Change has said that for global temperature rise to be contained within 2 degrees Celsius (the range to limit potentially catastrophic changes in natural systems), CO2 emissions need to be lower than 450 ppm. If we don't do anything to cut carbon-dioxide emissions, we may reach this dangerous threshold by as early as 2030. The Keeling Curve and the information it contains has informed and inspired initiatives to monitor atmospheric CO2 levels and determine their role in combatting climate change.

2) Cuyahoga River Aflame
On June 22, 1969, the Cuyahoga River caught fire in Cleveland, OH for the 14th time. Devoid of fish, coated in oil, and littered with debris, the Cuyahoga was considered one of the most polluted rivers in the United States at one point. But local residents weren't that concerned about water pollution, as it was viewed as a necessary consequence of industry. "The river that caught fire" in 1969 was famous for helping to spur the environmental movement of the 1960s. It helped incite an avalanche of water pollution control activities, resulting in the Clean Water Act, Great Lakes, and Water Quality Agreement as well as the establishment of the Environmental Protection Agency and the Ohio Environmental Protection Agency.

3) Ozone Hole
In 1985, scientists Joe Farman, Brian Gardiner, and Jonathan Shanklin first announced an observed annual thinning of the ozone layer over Antarctica. The authors argued that stratospheric chlorofluorocarbon (CFC) compounds, which have increased in concentration due to human activities, are responsible for the depletion of ozone, which shields the earth (and humans) from harmful ultraviolet (UV) radiation. The visualization of the ozone hole established proof of the thinning of the ozone layer, which motivated public awareness of health effects, including increases in skin cancer. It also provided a strong case for why investments in long-term monitoring are critical to help spot issues that arise when disruptions or changes to natural systems may occur slowly over time.

4) Great Pacific Garbage Patch
The Great Pacific Garbage Patch, also referred to as the Eastern Pacific Garbage Patch and the Pacific Trash Vortex, is a collection of floating marine debris, primarily pelagic plastics, chemical sludge and other materials trapped by an ocean gyre, located in the central North Pacific Ocean between Hawaii and California. The garbage patch was discovered in 1988 by the U.S. National Oceanic and Atmospheric Association (NOAA) and is considered an exceptional example of marine pollution. Scientists have collected up to 750,000 articles of plastic in a single square kilometer (or 1.9 million bits per square mile). Although of pressing concern for marine life and surrounding human populations, no nation has assumed responsibility for clearing the debris. It has become symbolic of the human threat to natural ecosystems and the inertia of nations to take collective action to address transboundary environmental concerns.

5) Environmental Kuznet's Curve (EKC)
One of the most daunting questions that confronts society today is whether environmental protection rises or declines with economic growth. Simon Kuznets, a Nobel Prize-winning economist, hypothesized that as an economy develops, inequality increases until a peak at which it then decreases. This seminal work became known as the 'Kuznets Curve,' which scholars then adapted to assess the nature of the relationship between environmental quality and economic development. Findings show that various indicators of environmental degradation (e.g., pollution levels) tend to worsen as economic growth increases, until average income reaches a "tipping point" at which pollution lessens. This inverted U-shape trajectory has been observed for environmental pollutants such as sulfur dioxide (which causes acid rain), nitrogen oxide (a driver of air pollution), lead (which has human health effects) and CFCs (see above discussion of the ozone hole). The Environmental Kuznets Curve has been used to describe environmental conditions for countries at varying stages of development, as well as to project at what levels of growth countries might be able to reduce pollution.

6) "Blue Marble"
Although not the first image of Earth from outer space, the iconic "Blue Marble" photograph left an indelible mark on society. This famous picture, captured on December 7, 1972 by the crew of Apollo 17 as they headed toward the moon on NASA's last unmanned lunar mission, provided the first proportional image of the planet. For the first time, Africa was not only seen but also recognized, as were the Arabian Peninsula and Antarctica's polar ice cap. People became more aware of the planet they call home, often using the image as a foundation for a new global consciousness. During the 1970s, the photo inspired a rise in environmental activism and was publicly acclaimed as a depiction of the Earth's frailty, vulnerability, and isolation in the vast expanse of space. Today, the "Blue Marble" is still regarded as one of the most salient images of our planet.

7) John Snow and Cholera
Arguably one of the most important contributions to public and environmental health, John Snow's maps of the cholera epidemic were revolutionary for their time. Following his intuition that the source of the cholera outbreak could be traced to the public water supply, Snow used a dot map to illustrate the cluster of cholera cases surrounding a water pump. He corroborated his findings through statistics, which showed that there was a connection between the quality of water and cholera cases. Not only did his work help quell the cholera epidemic, but it represented a landmark in the evolution of public health measures and disease eradication to demonstrate the importance of environmental factors on human health. Snow's work was also one of the earliest examples of applying data and mapping to better understand and environmental and public health issue.

8) The "Hockey Stick" Graph
In 1998 climate scientist Michael Mann and two colleagues endeavored to reconstruct the planet's past temperatures from half a millennium ago to show that recent global temperature rise was abnormal. The main finding was that recent northern hemisphere temperatures had been "warmer than any other year since (at least) AD 1400." The graph illustrating this point resembled a hockey stick: after a long period of relatively minor temperature variations -- the shaft -- it showed a sharp mercury upswing during the last century or so -- the blade. Initially facing immense criticism, this study served as a testament to the fact that the late 20th century warmth in the Northern Hemisphere was unprecedented during at least the last 1,000 years. This image provides undeniable evidence of human existence and increasing temperature rise.