The History of Modern Climate Science

The role of human-made carbon emissions is central to current discussions and scientific research on climate change. A major goal of the 1997 Kyoto Protocol was to reduce the carbon emissions of signatory states.¹ Likewise, its successor, the Paris Agreement is centrally focused on human-made carbon emissions. However, this crucial link between human-made carbon emissions, the greenhouse effect, and climate change, which is now a core component of modern climate science, was the subject of debate in the scientific community from the late nineteenth century and throughout the twentieth century. Indeed, the role of increased carbon dioxide emissions in increasing global temperatures only began to be widely accepted among the scientific community in the last four decades. This article traces the research in this area, which began in the early nineteenth century, and then considers the impact of such findings on state policy and initiatives beginning in the late nineteenth century, and continuing into the present where climate change has become a central (albeit polarizing) issue in international relations.

Beginning in the early nineteenth century, individuals interested in science began to research what we now refer to as the “greenhouse effect.” Today, we define the greenhouse gas effect as the role of greenhouse gases in the atmosphere, like carbon dioxide, “[trapping] heat radiating from Earth toward space.”² The entrapment of heat, in turn, leads to global warming. One of the first individuals to theorize on the greenhouse gas effect was Jean-Baptiste Joseph Fourier, a French scientist.³ In the 1820s, Fourier’s theoretical research led him to tentatively conclude that the atmosphere of the earth retains heat radiation. This, he believed, explained why the Earth was warmer than predicted by the Earth’s size and distance from the Sun.

Later in the century, the Irish physicist John Tyndall made advances on Fourier’s research. Tyndall determined that carbon dioxide in the atmosphere absorbs the solar radiation which is given off from the Earth’s surface.^4,5 He further concluded that the different gases in the atmosphere absorb heat at different degrees.⁶ From a modern perspective, Tyndall discovered the difference in radiation between different greenhouse gases. Hence, Tyndall’s experimental research laid the molecular foundation for the greenhouse effect.

Then, Swedish scientist Svante Arrhenius reached another highly significant conclusion that, arguably, drives the polarized debate on climate change today. Arrhenius claimed that human-produced carbon dioxide emissions (e.g. through the burning of fossil fuels) had the potential to increase global temperatures.⁷ He understood the implications of increasing production and release of carbon dioxide in the industrials age. However, in the early twentieth century, the conclusion reached by Arrhenius was treated with skepticism in the scientific community. Many scientists pointed to errors in Arrhenius’s calculations and assumptions about the climate system, and therefore many concluded that human activity played little role in producing climate change.

However, this widespread view was largely reversed with the end of World War II and the onset of the Cold War, as research greatly increased during these tense years. Indeed, the twentieth century yielded much in terms of climate science and related policy. Particularly important in this period was the work of American scientist Charles David Keeling, who established the global record for atmospheric carbon dioxide.⁸ A precise and accurate way to measure atmospheric levels of carbon dioxide remained elusive into the 1950s. Previous calculations lacked rigor, and this stood in the way of establishing a clear connection between human-produced carbon emissions, the greenhouse effect, and climate change. However, Keeling established a revolutionary method with which atmospheric concentrations of carbon dioxide could be measured. In 1956, the United States Weather Bureau tasked Keeling with establishing a baseline concentration of carbon dioxide in the atmosphere.

And so, in March 1958, at the Weather Bureau’s Mauna Loa Observatory in Hawaii, a carbon dioxide observatory was established. Later that month, the observatory recorded the first measurement for global atmospheric carbon dioxide levels. However, while the initial intent was to record a baseline level of carbon dioxide concentration, and then conduct another measurement ten years later, the “Keeling Record” at the Mauna Loa Observatory expanded and continued to be recorded. Daily averages continue into the present day.

It was these long-term observations made at Mauna Loa that revealed a definite and indisputable year-by-year increase in the atmospheric carbon dioxide concentrations. With this, the link between the burning of fossil fuels, the greenhouse gas effect, and climate change became clear in the 1960s. An idea that had been developing and circulating throughout the scientific community was finally proven. Indeed, the infamous “Keeling Curve”⁹ reveals the dramatic increases in atmospheric carbon dioxide concentrations with time.

In the later decades of the twentieth century, the findings of individuals such as Keeling increased public concern and governmental action on climate change caused by human activity. For Keith E. Peterman, a professor of chemistry, the first Earth Day, which was held on April 22, 1960, marked the start of the “modern environmental movement.”¹⁰ It was during this period that the public began to realize that human activity could negatively impact the Earth and climate. In 1979, the First World Climate Conference in Geneva expressed worry about the role of human activity in changing global climate. New research and data continued to reveal the link between global temperatures and concentrations of greenhouse gases such as carbon dioxide in the atmosphere, thus adding onto the work of Arrhenius and Keeling, among others. In 1981, researcher James Hansen and scientists at NASA’s Goddard Institute of Spaces published an article in Science which predicted that increased carbon dioxide concentrations would lead to global warming at a rate faster than was previously predicted.

Then, in the 1980s, concern for the greenhouse gas effect and climate change gave rise to the International Panel on Climate Change (IPCC). This organization of scientists has sought to provide an apolitical assessment of global climate trends, and is currently recognized as the authoritative leader in the realm of climate science. Indeed, the findings produced by the IPCC were central for the development of the United Nations Framework Convention on Climate Change (UNFCCC), which was established in 1992. Today, the UNFCCC, which seeks to prevent “…dangerous anthropogenic interference with the climate system,”¹¹ includes approximately two hundred nations. It was also responsible for the adoption of the Kyoto Protocol and the Paris Agreement. Thus, the scientific conclusions that were firmly established in the latter half of the twentieth century increased public concern and governmental efforts to study and prevent climate change.

The study of the greenhouse gas effect began with the research of scientist Fourier in the late eighteenth century. Yet, the notion that human activity could result in global warming was empirically proven only in the second half of the twentieth century by the data collected at the Mauna Loa Observatory in Hawaii with Keeling’s calculations. In the last several decades, this affirmation of the link between human-made carbon emissions, the greenhouse gas effect, and climate change continues to be strengthened by new and alarming research. While public concern and governmental actions has increased since the late twentieth century, the accelerated pace of global carbon emissions and the publication of concerning reports on climate change by scholars and organizations such as the IPCC reveals the urgency with which this matter must be treated.

Despite the current scientific consensus on climate change, polarization on the matter of climate change continues to challenge efforts to reduce carbon emissions and effectively respond to climate change. In the United States, the interests of industry lobbyists represent one barrier toward effective action. President Trump’s claims that climate change research is an exaggeration¹² represent another such hindrance. More broadly, the notion of climate change as a “tragedy of the commons”¹³—because the public or common nature of air and the Earth incentivizes overexploitation—is further suggestive of the challenges which bedevil more widespread acceptance and concern for scientific research on climate. Despite this, with the work of scientists of climate science converging to a consensus that change and action is imperative, it is now crucial for policymakers across the globe to take meaningful action.

1. “The Keeling Curve: Carbon Dioxide Measurements at Mauna Loa,” American Chemical Society, accessed January 6, 2019. https://www.acs.org/content/acs/en/education/whatischemistry/landmarks/keeling-curve.html.
2. “A Blanket Around the Earth,” Global Climate Change: Vital Signs of the Planet, accessed January 6, 2019. https://climate.nasa.gov/causes/.
3. “The Discovery of Global Warming,” American Institute of Physics, last modified February 2018. https://history.aip.org/history/climate/simple.htm#L_M085.
4.  Ibid.
5. Steven Graham, “John Tyndall: (1820-1893),” Earth Observatory, last modified October 8, 1999. https://earthobservatory.nasa.gov/features/Tyndall.
6. Richard Black, “Tyndall’s Climate Message, 150 Year On,” BBC, last modified September 28, 2011. https://www.bbc.com/news/science-environment-15093234.
7. “The Discovery of Global Warming,” American Institute of Physics, last modified February 2018. https://history.aip.org/history/climate/simple.htm#L_M085.
8. “The Keeling Curve,” Scripps Institution of Oceanography, accessed January 6, 2019. https://scripps.ucsd.edu/programs/keelingcurve/wp-content/plugins/sio-bluemoon/graphs/mlo_full_record.png.
9. “The Keeling Curve,” Scripps Institution of Oceanography, accessed January 6, 2019. https://scripps.ucsd.edu/programs/keelingcurve/wp-content/plugins/sio-bluemoon/graphs/mlo_full_record.png.
10. Keith E. Peterman et al., Climate Change and Education: The Sciences and Perspectives from the Global Stage, Volume 1 (Washington, D.C., American Chemical Society, 2017), 8. https://pubs.acs.org/doi/full/10.1021/bk-2017-1247.ch001.
11. Ibid, 9.
12. Emily Holden, “Trump Officials Argue Climate Change Warnings Based on ‘Worst-Case Scenario,’” The Guardian, last modified December 1, 2018. https://www.theguardian.com/environment/2018/dec/01/trump-officials-argue-climate-change-warnings-based-on-worst-case-scenario.
13. Roger Highfield, “Climate Change Will Get a Whole Lot Worse Before It Gets Better, According to Game Theory,” Wired, last modified July 6, 2018. https://www.wired.co.uk/article/climate-change-prediction-game-theory-tragedy-of-commons.