- This is part two of a two-part post. Read part one here.
By 1963, having directly measured a steady increase in CO2 levels over five years, Dave Keeling felt he had clearly shown the value of such non-stop monitoring. But that message hadn’t reached government decision makers. And so Dave swung into the first battle in the war to continue tracking the key greenhouse gas that has flared up repeatedly in the following decades.
Thanks to four new instruments called spectrophotometers, Dave had been able to use the same molecular movements that allow CO2 to absorb heat to measure it. Though his most famous site was at Mauna Loa in Hawaii, one was also installed in Antarctica. Another sailed on a ship and the final one stayed at Dave’s lab at Scripps Institution of Oceanography analysing samples collected in vacuum-filled five litre flasks from aircraft and elsewhere. Thanks to funds from 1957-1958’s International Geophysical Year a team of scientists was busy collecting a “snapshot” of CO2 data that Dave’s boss at Scripps, Roger Revelle, wanted.
So in 1961, Dave moved his family to Sweden for a year to work out exactly what the measurements were showing. He took a fellowship at the Meteorological Institute, University of Stockholm working with its new director Bert Bolin, who had earlier worked on the first computerised weather forecast. With measurements ongoing, annual ‘breathing’ cycles of rising and falling CO2 and the increasing trend underlying them became ever clearer.
Together, Dave and Bert found CO2 concentrations were going up by 0.06 ppm per month on average. Bert also undertook a series of complex calculations by hand to work out CO2 movement and cycles in its levels. In doing so he was showing how oceans, plants on land, and human fossil fuel burning contributed to the patterns that would later need computer models for fuller analysis. This, Dave felt, clearly showed why non-stop CO2 monitoring was needed rather than just snapshots. But by 1963 the shipboard spectrophotometer had come home, and Dave had also called back the one in Antarctica. And with funding cuts biting at the Weather Bureau, now part of the National Oceanic and Atmospheric Administration (NOAA), the staff at Mauna Loa fell from eight to three. And soon afterwards, a problem with Dave’s equipment proved too much for the overstretched team to fix.
“Suddenly there were no precise measurements being made of atmospheric CO2 anywhere,” he recalled. “I had seen the budget cut coming early in 1963 and had tried to prevent its terminating the CO2 program at Mauna Loa Observatory. I even went to Washington to plead for supplemental funding. This had no tangible effect, however, until the cessation of measurements actually occurred. The National Science Foundation (NSF) then found funds to pay for an additional technician at Mauna Loa. I learned a lesson that environmental time-series programs have no particular priority in the funding world, even if their main value lies in maintaining long-term continuity of measurements.”
Fighting on the scientific, financial and political fronts
By May 1964 Mauna Loa was back in business. As Dave’s team progressed slowly with their work once more, the importance of their findings was slowly dawning on the world. In 1969 the American Philosophical Society had taken note of rising atmospheric CO2 and invited Dave to tell them what it might mean. There he went beyond a previous focus on the “cyclic pattern owing to a seasonal variation in plant activity”. “Now we could clearly see that this pattern was superimposed on a rising trend,” he wrotes. “I noted in closing my talk that people held widely divergent views concerning a possible peril attending rising CO2, but that in 30 years ‘if present trends are any sign, mankind’s world, I judge, will be in greater immediate danger than it is today.’”
As people woke up to the CO2 situation, in the 1970s the newly founded UN World Meteorlogical Organisation (WMO) asked Dave to help set up an international tracking effort. To begin with, that won him the money for a big expansion to his team from the NSF. But within a year, it went back on that decision, saying that half of his work had become routine. The timing was bad: The spectre of unreliable CO2 measurements that Dave thought he had exorcised was also once again looming menacingly over him.
Dave and his colleagues had just found that spectrophotometers from different manufacturers could give varying measurements from the same air sample. The problem arose from the mixtures of nitrogen ‘carrier gas’ containing known CO2 amounts they used as ‘standards’ in the machines. At Scripps, Dave had improved his original manometer to make CO2 measurements precise to 0.1 ppm, and used it to produce the standards. The scientists effectively got their CO2 measurements by comparing the result they got from air samples to these standards.
When comparing three different machines side-by-side with the same air sample and standard, they noticed two gave air measurements above the standard, while the other fell below it. The problem arose because air samples contain oxygen as well as nitrogen, and this affected some machines’ measurements more than others. All of Dave’s teams data had been based on the same machines and standards so they weren’t affected, but comparing with other groups was now difficult.
But the scientific problem turned into an opportunity to solve the financial one. The UN made Dave’s Scripps lab the ‘Central CO2 Laboratory of WMO’, and gave him the money needed to resolve the carrier gas problem and strictly monitor data reliability. That suited Dave’s desire to get “data that truly reflected nature”. “I hadn’t forgotten that CO2 measurements published before I began my studies had been terribly wrong but were generally regarded as valid,” he wrote. “I wanted to remain directly involved in CO2 data gathering to be able to judge the quality of such data on my own terms.”
The Keelings’ work is not over
Having delayed publishing CO2 results from 1957-1971 while working on this problem, what Dave finally published in 1976 was recognisably what’s now called ‘the Keeling Curve’. It showed each year’s annual CO2 cycle laid onto a continuous rise in CO2 over more than a decade and hints of links to longer El Niño cycles.
The same year, just as NSF and the WMO wanted to cut funding for Dave’s group, CO2 gained interest for a new reason. The new US Department of Energy (DOE) wanted to compare the risks of global warming driven by burning fossil fuels with risks being raised in objections to nuclear power. NSF warned Dave against applying for funding again, but this new popularity ensured he got money from NOAA and DOE.
For decades this funding balanced precariously on a knife-edge. At first, NOAA looked to take over responsibility for CO2, but Dave’s ongoing passion for accurate measurements ensured his continued involvement. Problems started because NOAA was repeatedly swapping between instruments, without taking the carrier gas effect into account. They also tried using smaller flasks, which were more likely to get contaminated. Then in the 1990s the DOE cut back its interest from broad CO2 research to focussing only on land-based processes, such as how it might speed crop growth. In doing so, it seemingly went from focusing on CO2’s risks to its benefits. However Dave’s work was clearly and increasingly relevant in this area, and so it let him bring his curve into the new millennium.
In an autobiographical sketch written in 1998, Dave reflected on what he had learned about CO2’s role in global warming since he first collected air samples. He said that the “prudent attitude would be to heed the rise in atmospheric CO2 concentration as serious unless proven to be benign”. “Four decades later, there is a hint, perhaps more than a hint, of peril,” he wrote. “Nevertheless, and despite the heightened political awareness of the greenhouse problem indicated by the Kyoto meeting last winter, most governments have shown little heightened interest in environmental monitoring.”
Though Dave died in 2005, the measurements at Mauna Loa and 12 other sites continue with his son Ralph now leading the group. In May this year, the ongoing rise in CO2 levels hit a new milestone: Concentrations reached 400 parts per million (ppm). That’s up from around 310 ppm when Dave started his measurements. And talking to top research journal Nature when announcing this, Ralph revealed he still struggles to find the money needed for tracking. “The amount of money that I’m able to obtain for the programme has diminished over time,” he said.
To me, it’s ridiculous that both the speed of CO2 increase and the funding to monitor it are in much the same situation as they were 50 years ago. And so I hope that all of us concerned about global warming can channel the fighting spirit that Dave Keeling showed to help change that.
Ralph Keeling talks about CO2 levels crossing the 400 ppm threshold
Spencer Weart’s book, ‘The Discovery of Global Warming’ has been the starting point for this series of blog posts on scientists who played leading roles in climate science.
Charles D. Keeling (1998). REWARDS AND PENALTIES OF MONITORING THE EARTH Annual Review of Energy and the Environment DOI: 10.1146/annurev.energy.23.1.25
Monastersky R (2013). Global carbon dioxide levels near worrisome milestone. Nature, 497 (7447), 13-4 PMID: 23636369
This year I’ve already written about the following pivotal climate scientists who came before Dave Keeling, or were around at the same time: Svante Arrhenius, Milutin Milanković, Guy Callendar part I, Guy Callendar part II, Hans Suess, Willi Dansgaard, Dave Keeling part I