Ralph Keeling

Chris Bentley/MEDILL

Second generation climate scientist Ralph Keeling warns that the spectacular rise in carbon dioxide levels caused by burning fossil fuels could be trivial compared to what's to come. 


Tracking carbon dioxide and climate — It's all in the family

by Chris Bentley
Oct 22, 2010

Keeling slide: collective action

The other side of CO2


Climate scientist Ralph Keeling was born alongside the modern environmental movement. 


His father, geochemist Charles David Keeling, had just begun an ambitious project to measure carbon dioxide in the air at Hawaii’s Mauna Loa volcano. His initial results were the first to bring attention to rising levels of CO2 and, by 1960, he famously linked the greenhouse gas to fossil fuel consumption and provided seminal evidence for global warming.


By the time Ralph went into the family business, his father’s experiment had sparked an environmental movement by bringing global attention to the fact that human activity could substantially affect the composition of the atmosphere.

Today, the saw-toothed upswing of the Keeling Curve of  CO2  is practically synonymous with the public’s vision of climate change. The rise in the gas has been relentless, and so has the father-son team in measuring it — atmospheric concentrations had risen from 312 parts per million in 1956 to almost 380 when Ralph took over supervision of the project after his father died in 2005. Meanwhile, he had undertaken his own venture to measure atmospheric oxygen concentrations — the other side of Earth’s natural respiration.

Ralph Keeling put his work into perspective Monday as the keynote speaker at Northwestern University’s second annual climate change symposium. His address entitled “Rising CO2: A Never Ending Story?” paid homage to his father, who received his PhD in chemistry from Northwestern in 1954. Both Keelings conducted the bulk of their research for the Scripps Institute of Oceanography at the University of California San Diego. 

“What we’ve seen so far, while spectacular, is tiny compared to what we could see,” Ralph Keeling said about the unpredictable nature of future climate change. His measurements of oxygen — taken at nine stations around the world since 1989 — decline in a zig-zag that is almost a mirror image of the rise in CO2. Except that the changes are tiny compared to the total amount of oxygen in the atmosphere.  

While the depletion of oxygen isn’t significant enough to be an environmental problem itself, Keeling said, the rates of change tell us about how land and the oceans remove CO2 from the atmosphere. The ocean acts like a sponge for excess carbon dioxide, neutralizing the acidic compound and burying it deep underwater, without releasing oxygen in exchange. On the other hand, plants and other organic stocks of carbon on land are oxygen sources. 

“Land uptake is not a very secure method of storing CO2 — ocean uptake is more long-term,” Keeling said. He added that in emitting greenhouse gases by burning fossil fuels, humans rely on these ocean sinks to carry out natural mitigation at no cost. “It behooves us to know what the natural sinks are doing,” he added, because if we don’t, “we are not in a position to gauge the effectiveness of the measures we take.” 

Understanding exactly how and how much the ocean buffers the greenhouse gas effect is also important, he said, because changing the trajectory of CO2’s atmospheric concentration has profound effects on the sinks that absorb it.

For many marine organisms, those effects are already evident. In addition to a lower pH, ocean creatures have to endure an environment that is becoming increasingly carbon-rich and oxygen-poor. “Biology in the ocean is facing at least three separate challenges all tied to rising CO2 in the air,” Keeling said.  

Ancient air pockets preserved in ice cores from the Arctic and Antarctic show that COlevels stablized below about 300 parts per million for hundreds of thousands of years prior to the Industrial Revolution. They are now at 390 ppm.

Climate needs cathedral builders, Keeling concluded. He borrowed a conceptual plot from social science research to make the point. He charted the immediacy of gratification against the number of people benefitting from an activity. While it is easy to please small numbers of people on short time scales, he said, it is gets increasingly difficult to motivate actions that require large numbers of people and won’t payoff for a very long time. Keeling pointed out that “cathedral building” is a formidable task that inspires high levels of motivation despite a seemingly far-off gain. “The payoff is in the afterlife, in some sense,” he said, “but people did build cathedrals.” 

The university sponsored the symposium in collaboration with the department of Earth & Planetary Sciences; the Environmental Science, Engineering and Policy Program; the Program in Environmental Policy and Culture; and the Initiative for Sustainability and Energy at Northwestern.