'One physical system': Tansley's ecosystem as Earth's critical zone

Integrative concepts of the biosphere, ecosystem, biogeocenosis and, recently, Earth's critical zone embrace scientific disciplines that link matter, energy and organisms in a systems-level understanding of our remarkable planet. Here, we assert the congruence of Tansley's (1935) venerable ecosystem concept of 'one physical system' with Earth science's critical zone. Ecosystems and critical zones are congruent across spatial-temporal scales from vegetation-clad weathering profiles and hillslopes, small catchments, landscapes, river basins, continents, to Earth's whole terrestrial surface. What may be less obvious is congruence in the vertical dimension. We use ecosystem metabolism to argue that full accounting of photosynthetically fixed carbon includes respiratory CO₂ and carbonic acid that propagate to the base of the critical zone itself. Although a small fraction of respiration, the downward diffusion of CO₂ helps determine rates of soil formation and, ultimately, ecosystem evolution and resilience. Because life in the upper portions of terrestrial ecosystems significantly affects biogeochemistry throughout weathering profiles, the lower boundaries of most terrestrial ecosystems have been demarcated at depths too shallow to permit a complete understanding of ecosystem structure and function. Opportunities abound to explore connections between upper and lower components of critical-zone ecosystems, between soils and streams in watersheds, and between plant-derived CO₂ and deep microbial communities and mineral weathering.

'A thorn in the side of European geodesy': measuring Paris-Greenwich longitude by electric telegraph

The difference in longitude between the observatories of Paris and Greenwich was long of fundamental importance to geodesy, navigation and timekeeping. Measured many times and by many different means since the seventeenth century, the preferred method of the later nineteenth and early twentieth centuries made use of the electric telegraph. I describe here for the first time the four Paris-Greenwich telegraphic longitude determinations made between 1854 and 1902. Despite contemporary faith in the new technique, the first was soon found to be inaccurate; the second was a failure, ending in Anglo-French dispute over whose result was to be trusted; the third failed in exactly the same way; and when eventually the fourth was presented as a success, the evidence for that success was far from clear-cut. I use this as a case study in precision measurement, showing how mutual grounding between different measurement techniques, in the search for agreement between them, was an important force for change and improvement. I also show that better precision had more to do with the gradually improving methods of astronomical, time determination than with the singular innovation of the telegraph, thus emphasizing the importance of what have been described as 'observatory techniques' to nineteenth-century practices of precision measurement.

Darwin and the geological controversies over the steady-state worldview in the 1830s

In the first part of this paper, I will show that although Darwin's geological works only covered the first years of his scientific career, these played a non-negligible role in the earth sciences of the mid-nineteenth century. His intellectual proximity with Charles Lyell often made him his disciple. This is indeed the case with respect to debates over 'gradual' soil movements and 'catastrophic' soil movements, and for 'steady-state' cycles as opposed to 'directionalistic' ones. This being said, it is also true that in South America Darwin saw geological processes which were incompatible with Lyell's explanations. It must therefore be recognized that Darwin held a middle-of-the-road position between uniformitarianism (Lyell) and catastrophism (Humbolt and von Buch), at least as far as some geological questions were concerned. In the second part of the paper, debates on geological issues during Darwin's active years will be put in the methodological context of the Scientific Revolution of the seventeenth century.

[Inventories of the Earth. Mineral resource appraisals and the rise of resource economics]

How do the earth sciences mediate between the natural and social world? This paper explores the question by focusing on the history of nonfuel mineral resource appraisal from the late nineteenth to the mid twentieth century. It argues that earth sciences early on embraced social scientific knowledge, i.e. economic knowledge, in particular, when it came to determining or deposits and estimating the magnitude of mineral reserves. After 1900, assessing national and global mineral reserves and their "life span" or years of supply became ever more important, scaling up and complementing traditional appraisal practices on the level of individual mines or mining and trading companies. As a consequence, economic methods gained new weight for mineral resource estimation. Natural resource economics as an own field of research grew out of these efforts. By way of example, the mineral resource appraisal assigned to the U.S. Materials Policy Commission by President Harry S. Truman in 1951 is analyzed in more detail. Natural resource economics and environmental economics might be interpreted as a strategy to bring down the vast and holistically conceived object of geological and ecological research, the earth, to human scale, and assimilate it into social matters.

Multa curiosa: Vallisneri's early studies on earth sciences

In 1687, after he graduated in Medicine, young Antonio Vallisneri (1661-1730) returned in the Duchy of Modena and Reggio. In those years he mainly served as general practitioner; nevertheless, he also devoted many studies to various aspects of the natural sciences. He performed many observations, accurately reporting them in seven Quaderni, which were compiled between 1694 and 1701. Though the Earth sciences occupy only a small part of these diaries, the accuracy of the notes makes them a precious token of the scientific praxis adopted by the author in this field of study. This paper deals with the analysis of these early geological reports, pointing out the main criteria of Vallisneri's experimental method and paying attention to the great significance which these documents had in the elaboration of some of his published works.

Exploring Greenland: science and technology in Cold War settings

This paper explores a vacant spot in the Cold War history of science: the development of research activities in the physical environmental sciences and in nuclear science and technology in Greenland. In the post-war period, scientific exploration of the polar areas became a strategically important element in American and Soviet defence policy. Particularly geophysical fields like meteorology, geology, seismology, oceanography, and others profited greatly from military interest. While Denmark maintained formal sovereignty over Greenland, research activities were strongly dominated by U.S. military interests. This paper sets out to summarize the limited current state of knowledge about activities in the environmental physical sciences in Greenland and their entanglement with military, geopolitical, and colonial interests of both the USA and Denmark. We describe geophysical research in the Cold War in Greenland as a multidimensional colonial endeavour. In a period of decolonization after World War II, Greenland, being a Danish colony, became additionally colonized by the American military. Concurrently, in a period of emerging scientific internationalism, the U.S. military "colonized" geophysical research in the Arctic, which increasingly became subject to military directions, culture, and rules.