08 October 2024
Moving Lines: Climate Change, Maps and Boundaries
Huw Rowlands, India Office Records Map Collection
Introduction
Climate change is already affecting people all over the world and the impacts are expected to increase, affecting more people and more of the planet. The challenges we face include droughts and flooding, extreme temperatures, degradation of agricultural land, and the extinction of wildlife. Our governments are responding to such challenges in different ways and to varying degrees. In this article, I consider how maps help us monitor and communicate the effects of climate change, the relationship of maps to geographical ideas, and how governments are reacting as climate change is redrawing our national borders.
Maps and Climate Change
Maps are useful for monitoring the natural world and observing impacts of climate change which include retreating glaciers and rising sea levels. A map is like a snapshot of the Earth’s surface; a series of snapshots enables changes to be monitored over time.
An example is the dramatic retreat between 1945 and 1998 of Breidamerkurjökull, Europe's largest glacier, in South East Iceland. A study published in 2017 included the two maps in figure 1, which show the changes clearly. Using earlier maps as well, the research revealed that the glacier had retreated slowly from the end of the 19th century, faster from the 1930s, and faster again since the 1990s. Over that whole period, the front edge of the glacier has retreated between 4 and 7 km. The area of ice lost between 1890 and 1945 was 33 km2, with an additional 81 km2 lost between 1945 and 2010.
Figure 1. a) and b). Breiđamerkurjökull : South East Iceland : August 1945 and August 1998. Glasgow: University of Glasgow 1969, 2006. Print. British Library Maps X.6617.
Maps have been similarly used in other environments including in the world’s largest river delta in the Bay of Bengal. In a 1997 study, Bandyopadhyay looked at erosion of islands in one part of the Ganges delta – the Hugli estuary. He used historic maps from 1851 to 1997 to study erosion rates and noticed that the relationship between island erosion and water depth was different when he compared reclaimed islands with natural (non-reclaimed) islands. The reclaimed islands already need large-scale maintenance to mitigate erosion. He concluded that sea level rise will further increase erosion and lead to greater instability. The costs of continuing to mitigate such changes will be significant, and instead he recommended controlled retreat from the affected areas and the relocation of the resident population.
Figure 2. Bandyopadhyay, Sunando. Changes in the tidal islands of the Hugli estuary between 1851-55 and 1997. Survey of India Maps: Indian Atlas sheet 121; 1” Series sheets 79B/4, 79C/1, 79C/2; and subsequent 1:50,000 coverage of the same areas. British Library IOR/X/9004, IOR/X/9053, and Maps 52415.(108.)
The Hugli was also the focus of Empire and Ecology in the Bengal Delta by Debjani Bhattacharyya. In this 2018 book, Bhattacharyya looked at the political and legal impacts of British colonial India on the marginal landscape of the Hugli around Kolkata. She used maps of the River Hugli, including those collected by Frederick Barlow and held in the India Office Records at the British Library. Barlow’s map collection shows the effects of erosion and deposition on the course of the river, its navigation channels, and the shape and position of its sand bars and islands. Figure 2 shows how maps that focus on the river, can imply a clear distinction between the river and the land which does not reflect the complexity on the Earth’s surface.
Figure 3. Map of the space from the Bay of Bengal to Calcutta (1790) showing sandbars. Frederick Barlow Collection of Maps of the River Hoogly. British Library IOR/X/9128.
One of Bhattacharyya’s lines of enquiry was to examine the ways laws were used to create property, and the role of maps in that process. Prior to colonisation, the area around Kolkata was composed of ‘urban marshes’ and ‘floating, watery soils’. Such a mixed and mobile environment was not considered to be property until the land could be distinguished from the water. She explained how the mobile, soaked landscape was transformed into a dry, propertied geography between 1760 and 1920. Land was created through drainage and turned into property, which was bought and sold, often speculatively. When mapped, this re-imagined and transformed landscape appears to lose its characteristics of urban marsh. Maps shape and fix mental geographical images, and do so at even larger scales, while the underlying natural characteristics are forgotten.
Figure 4. Engraved map with pictorial inserts of Calcutta by an unknown engraver, published in 1852 under the superintendence of The Society for the Diffusion of Useful Knowledge. British Library IOR/X/14784
Maps and Geographical Ideas
In Mapping an Empire, Matthew Edney explored the ways in which maps project geographical ideas. Maps of the British Empire in India, he argued ‘came to define the empire itself, to give it territorial integrity … The empire exists because it can be mapped.’ Edney argued that the British deluded themselves that their science enabled them to know the “real” India. But what they created in the process was a British India. Through climate change, the dissonance between geographical ideas that can be mapped, and their underlying environments is becoming increasingly visible; climate change is increasing the difference between our mapped ideas of the land and the land itself. The consequences are challenging, not least for the geographical definition of nations and their boundaries.
The Grafferner ice sheet in the Ötzal Alps hides a border. The international border between Italy and Austria traces a watershed – the line separating two river drainage systems. The Danube drains northwards into Austria and to the Black Sea, and the Adige drains south into Italy and to the Adriatic Sea. Using watersheds as international borders has long been a convenient way of drawing borders. When the watershed is formed on rock, it can be very stable over human timescales. But when it is formed on a changeable mass of snow and ice, on a warming planet, it is continuously redrawn. As we saw at the start of this article, ice is clearly disappearing. In the Ötzal Alps, the watershed is moving as the ice retreats, and the international border is moving with it, in more than 100 places.
As James Crawford explained in The Edge of the Plain, the first intergovernmental response to this moving border was to maintain the surface area of each state. So, if one part of the border moved North with the watershed, increasing the area of Italy, Italy ceded the same area of territory to Austria in exchange. Now that the rate of change has increased so much, this complex and time-consuming process is unsustainable. The Italian state mapping agency, IGM, proposed an alternative to the Italian Ministry of Foreign Affairs in 1994 that eventually became law in a bilateral agreement between the two countries. Now, wherever the watershed is changed by natural processes, the surveyors follow the new line and redraw the map. According to Crawford, this became the first-ever recognition in law, in history, anywhere in the world, that a border was not immobile, that it could shift on its own.
Figure 5. The border between Italy and Austria running over glaciers in the Ötzal Alps Italy 1:100,000 Sheet 1 Passo di Resia. GSGS 1943, published by War Office. British Library. Maps Y.4537.
Conclusions
The example of the Ötzal Alps shows how governments might face the challenges of climate change redrawing national borders. In a similar case along the border between Italy and Switzerland, however, the challenges were slightly more complicated. As the ice is retreating, the watershed dividing the two countries is passing under a ski lodge, which has until now been in Italy. Part of the building now lies in Switzerland, and both the economic value of the lodge and the fact that both countries’ planning laws technically apply to its redevelopment mean that an agreement has been harder to reach. Imagine the scale of the challenges facing governments when rising sea levels and climate change affect borders in areas with large populations and extensive valuable urban infrastructure. What roles might historic maps and modern mapping technologies play then?
References and Further Reading
Bandyopadhyay, Sunando. Changes in the tidal islands of the Hugli estuary between 1851-55 and 1997. From Coastal changes in the perspective of long term evolution of an estuary: Hugli, West Bengal, India. In: Quaternary Sea Level Variation, Shoreline Displacement and Coastal Environment (Proceedings of International Seminar, INQUA Shoreline Indian Ocean Subcommission, 20–26 Jan 1997, Tamil University, Thanjavur) [] Editors: Rajamanickam, V.J. & Tooley, M.J. (pp.103–115). Publisher: New Academic Publishers, Delhi-110002. ISBN 81-86772-06-5. DOI:10.5281/zenodo.7264750
Bhattacharyya, Debjani. Empire and Ecology in the Bengal Delta: The Making of Calcutta. Studies in Environment and History. Cambridge: Cambridge University Press, 2018. BL YC.2019.a.494
Crawford, James. The Edge of the Plain: How Borders Make and Break Our World. United States: W. W. Norton, 2023. BL ELD.DS.710119
Edney, Matthew H. Mapping an Empire: The Geographical Construction of British India, 1765-1843. University of Chicago Press, 1997. BL YC.2003.a.2003
Guðmundsson, Snævarr, H. Björnsson, and F. Pálsson. "Changes of Breiðamerkurjökull glacier, SE-Iceland, from its late nineteenth century maximum to the present." Geografiska Annaler: Series A, Physical Geography 99, no. 4 (2017): 338-352.
Huw Rowlands