Keeling Curve Research Articles

Environmental Monitoring?s Image Problem

Earlier this year the scientific world was shocked by the revelation that the famous Keeling Curve may come to an end due to lack of funding. The curve is the result of 56 years of continuous atmospheric monitoring of carbon dioxide, initially in Hawaii by Charles David Keeling and more recently by the Scripps Institute of Oceanography at the University of California San Diego. The data provided convincing evidence of carbon dioxide’s role in global warming and will be essential in assessing the success of mitigation strategies. After a heartfelt plea from Ralph Keeling, the project was saved, at least temporarily, thanks to a mixture of private and government funds and a successful crowd funding campaign. The plight of the project highlights the fragility and importance of long-term environmental monitoring. In a recent editorial, I lamented the lack of environment data for the New York City area which hampered our ability to draw concrete conclusions from data obtained following Hurricane Sandy. I contrasted this to the recent completion of a forty year project by the British Geological Survey which resulted in a comprehensive map of several elements in the United Kingdom. Why are similar initiatives not occurring in the United States? The difficulty appears to be in securing necessary funds for monitoring projects which do not appear to offer a useful product or exciting innovations.

A dent in carbon's gold standard

The global uptake of carbon by land plants may be greater than previously thought, according to observations based on the enigmatic Keeling curve of rising atmospheric carbon dioxide. See Letter p.579 Quantifying global-scale carbon assimilation by plants, or gross primary production (GPP), has been difficult because there are no direct measures at scales greater than the leaf level. An analysis of nearly 30 years of unpublished records of the oxygen isotope (18O/16O) composition of atmospheric carbon dioxide from sampling sites worldwide has provided a means of estimating the GPP that is not reliant on modelling. The data reveal previously unrecognized interannual fluctuations that are driven by El Nino climate events. The effect propagates from the tropics to higher latitudes through the tropical hydrological cycle. Recovery from El Nino events is rapid, implying a shorter turnover time for CO2 than is generally assumed, and suggests a best-guess figure for global GPP of 150–175 petagrams of carbon per year, rather than the current estimate of 120 petagrams.

Carbon Sequestration and Its Role in the Global Carbon Cycle

The science of climate change, and the role carbon dioxide (CO2) plays in it, was launched into the public consciousness by Charles David Keeling's investigations in the late 1950s. Keeling conducted early atmospheric carbon measurements high on Hawaii's Mauna Loa volcano and found that even after ruling out natural fluctuations, the concentration of CO2 in the atmosphere was increasing year after year. The findings, published in the 1960s, led to the now iconic Keeling curve and raised several questions about the contribution of fossil fuel burning to atmospheric CO2 concentrations. The AGU monograph Carbon Sequestration and Its Role in the Global Carbon Cycle, edited by Brian J. McPherson and Eric T. Sundquist, moves beyond the “how much?” and “where is it coming from?” of atmospheric CO2 and provides an interdisciplinary look at what we can do to address imbalances in the carbon cycle. In this interview, Eos talks with McPherson.

A changing ocean seen with clarity

The Hawaiian archipelago, the most remote group of islands on Earth, has long been associated with the world's most recognizable image of global change. The Mauna Loa atmospheric CO2 record, begun in March 1958 by Charles David Keeling, shows with startling clarity the saw-tooth pattern of the seasonal changes of land vegetation, and the still astonishing, dominating, rise forced by fossil fuel burning which is rapidly changing our world. Within perhaps only 5 years the peak in the annual signal atop Mauna Loa will touch the 400 ppm by volume mark, which would have been inconceivable to scientists of the first half of the twentieth century. But there is one huge and environmentally critical signal that is not easily seen in the “Keeling curve,” and that is the oceanic uptake of fossil fuel CO2. In this issue of PNAS, Dore et al. (1) document with great clarity the changes in ocean CO2 chemistry and pH occurring in the ocean in the waters off Hawaii from fossil fuel CO2 invasion.

A fresh perspective

Nearly fifty years ago —things were up and running by March 1958 — Charles Keeling and colleagues began a series of measurements of atmospheric CO2 on Mauna Loa in Hawaii. The results, made graphic in the jagged 'Keeling curve' running across this week's cover, made the world take notice — eventually. The Mauna Loa measurements constitute the longest continuous record of atmospheric CO2 in the world. The steady rise in CO2 that they record now forms the accepted backdrop to today's climate science and economic and political decision making. As well as being an important resource in itself, the Mauna Loa record highlights the vital importance of Earth monitoring programmes. The fiftieth anniversary of the start of this work is marked in this issue by News Features and other pieces on the Earth monitoring being done today, historical pieces on the Mauna Loa data and more.