Climate Change: A Gradient of Perception

Now that climate change sits among the central concerns of international society, we can return to a simple question. How did human beings come to read the atmosphere as a system? It has been a little over two hundred years since 1824, when Joseph Fourier published Remarques générales sur les températures du globe terrestre et des espaces planétaires. What has accumulated in those two centuries is, we think, a chain of observation and theory ── a slow response to the structure of the world.

The Beginnings of Climate Awareness (1800s–1850s)

Scientific attention to climate begins in the early nineteenth century. In 1824, the French mathematician Joseph Fourier laid the theoretical groundwork for what we now call the greenhouse effect. The atmosphere lets sunlight through while retaining heat radiated from the surface ── without this balance, he argued, Earth would be a colder body than it is.¹

Around the same time, the German naturalist Alexander von Humboldt, through his South American expedition (1799–1804), produced the first systematic record that human activity could alter local climate. In Venezuela, he documented in detail how deforestation reshaped regional weather. In his later major work, Cosmos (1845), this view crystallized into something larger ── climate as a planet-scale system of mutual relations.² Climate science, we want to note, begins as something already systemic ── an Earth that exists through its relations.

Industrial Smoke and the Chemist's Eye (1850s–1890s)

The black smoke rising from factory chimneys was, at the time, one of the lines that drew the outline of progress. Steam locomotives crossed continents. The skies of cities took on the color of industry.

In Britain, smoke regulation grew out of the Smoke Nuisance Abatement Acts of 1853 and 1856, and was eventually folded ── alongside sanitation, housing, and water supply ── into the Public Health Act of 1875. But these regulations focused on visible smoke. The composition of the air itself would have to wait a little longer for sustained attention.

Chemistry filled that gap. In 1872, the Scottish chemist Robert Angus Smith documented in Air and Rain the air pollution and rainwater acidity around the industrial city of Manchester. The observation that industrial activity was rewriting the chemistry of the atmosphere appeared here, for the first time, with a quantitative outline.³

In 1859, the Irish physicist John Tyndall demonstrated experimentally that carbon dioxide (CO₂) and water vapor absorb thermal radiation.⁴ What Fourier had anticipated as theory, Tyndall confirmed in the laboratory.

In 1896, the Swedish scientist Svante Arrhenius set out, quantitatively, the idea that anthropogenic CO₂ emissions could affect Earth's temperature.⁵ His estimate was that doubling atmospheric CO₂ might raise global temperatures by 5–6°C ── higher than today's best estimate of equilibrium climate sensitivity (around 3°C)⁶, but a calculation, we can say, of remarkable foresight in qualitative terms.

The Century of Observation (1900s–1970s)

In the twentieth century, climate science shifted its center of gravity from theory to observation.

In 1938, the British engineer Guy Stewart Callendar showed a correlation between rising CO₂ concentrations and rising temperatures since the Industrial Revolution. By carefully arranging meteorological data from the nineteenth century onward, he identified the link between CO₂ from fossil-fuel combustion and changes in temperature ── a finding later known as the Callendar effect.⁷

In 1957, Roger Revelle (oceanographer) and Hans Suess (geochemist), both of the Scripps Institution of Oceanography, found that the ocean's capacity to absorb CO₂ has limits, and that excess CO₂ accumulates in the atmosphere.⁸ The previously implicit assumption that the ocean would simply absorb the surplus was corrected here.

The following year, in March 1958, Charles David Keeling began continuous measurements of atmospheric CO₂ at Mauna Loa, Hawaii. At an elevation of 3,397 meters, on a site relatively undisturbed by direct human activity, the station became a reference point for tracking global CO₂ variations over time. The data eventually crystallized into the Keeling Curve ── a record that made visible, to anyone willing to read it, the slow rise of atmospheric CO₂, breathing with the seasons.⁹

The 1972 Stockholm Conference was the first major international setting at which environmental issues were confirmed as a problem crossing national borders.¹⁰ Observational values, here, entered the vocabulary of international politics for the first time.

International Recognition (1980s–1990s)

In 1988, the NASA climate scientist James Hansen testified before the U.S. Senate Committee on Energy and Natural Resources, roughly as follows. The warming trend now under way cannot be explained by natural variation. We can say so with 99 percent confidence. The warming may therefore be regarded as the consequence of human activity. This careful confidence was reported in media around the world, and climate change began to enter the language of politics.¹¹

The IPCC (Intergovernmental Panel on Climate Change), established the same year, took on the role of evaluating and integrating scientific knowledge of climate change as a network connecting scientists across nations.¹²

In 1992, at the Earth Summit, the UN Framework Convention on Climate Change (UNFCCC) was adopted.¹³ The Kyoto Protocol followed in 1997. From this period onward, response to climate change became part of international policy. Coverage in the press grew, and public awareness widened with it.

Reflections from History

What two centuries of climate science describe is, in part, a long and recurring gap between scientific finding and social recognition. Fourier's theoretical foundation, Humboldt's field observations, Arrhenius's quantitative prediction, Keeling's continuous measurement ── each took decades to be translated into the vocabulary of society.

But the same history shows another face. The world has, slowly, opened to us as a structure of mutual relations. What Fourier saw was a flow of heat. What Humboldt saw was a network of relations. What Tyndall saw was the behavior of molecules. What Keeling saw was the breathing of the atmosphere.

Climate change cannot be captured by a single observation, or a single instrument. It is also a vantage we have come to hold, slowly, through a long attempt to read the structure of the world.

Data continues to be updated at observation stations across the world. We are present at the continuation of that record.

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Footnotes

1. Fourier, J. (1824). "Remarques générales sur les températures du globe terrestre et des espaces planétaires". Annales de Chimie et de Physique, 27, 136–167. ↩

2. von Humboldt, A. (1845). Cosmos: A Sketch of a Physical Description of the Universe, Vol. 1. Harper & Brothers. ↩

3. Smith, R.A. (1872). Air and Rain: The Beginnings of a Chemical Climatology. Longmans, Green, and Co., London. ↩

4. Tyndall, J. (1859). "Note on the Transmission of Heat through Gaseous Bodies". Proceedings of the Royal Society of London, 10, 37–39. ↩

5. Arrhenius, S. (1896). "On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground". Philosophical Magazine and Journal of Science, 41, 237–276. ↩

6. IPCC. (2021). Climate Change 2021: The Physical Science Basis. Cambridge University Press. ↩

7. Callendar, G.S. (1938). "The Artificial Production of Carbon Dioxide and Its Influence on Temperature". Quarterly Journal of the Royal Meteorological Society, 64, 223–240. ↩

8. Revelle, R., & Suess, H.E. (1957). "Carbon Dioxide Exchange Between Atmosphere and Ocean and the Question of an Increase of Atmospheric CO₂ during the Past Decades". Tellus, 9, 18–27. ↩

9. Keeling, C.D. (1960). "The Concentration and Isotopic Abundances of Carbon Dioxide in the Atmosphere". Tellus, 12, 200–203. ↩

10. United Nations. (1972). Report of the United Nations Conference on the Human Environment. Stockholm, 5–16 June 1972. ↩

11. Hansen, J. et al. (1988). "Global Climate Changes as Forecast by Goddard Institute for Space Studies Three-Dimensional Model". Journal of Geophysical Research, 93, 9341–9364. ↩

12. IPCC. (1990). First Assessment Report. Cambridge University Press. ↩

13. United Nations. (1992). United Nations Framework Convention on Climate Change. FCCC/INFORMAL/84. ↩