Climate change: island life in a volatile world

## 3.2 Migrations of life

### 4 Volatile worlds

# 4.1 When climate changes

We have seen that human-induced climate change poses a challenge for people who live on islands. Such changing patterns and extremes of climate also put pressure on the other living things that are part of the make-up of island territories. However, long before human beings became aware that they could transform the flows that constitute climate, they and other species were already taking advantage of these same flows to help create the very territories that are now under threat. But have these flows themselves changed over time, even without human input? As mentioned in Section 3.2, it has been known at least since Darwin's day that sea levels have changed dramatically over time. This raises some interesting questions about contemporary changes in climate, and how we respond to their effects. In this section, we explore some of the ways in which the earth itself shifts, including the flows we call ‘weather’ or ‘climate’, and the very ground beneath our feet. This takes us into the realm of momentous changes that occur even without human impact or influence, which in turn raises some thorny questions for the issue of responsibility.

As you may recall from Section 3.1, anthropologists suggest that the early settlers of the Pacific probably departed from eastern Asia, perhaps via the islands off Southeast Asia. From here, they set out into the world's largest reach of open water, with little way of knowing what they might find.

## Activity 7

In Activity 5, the question was posed of how the Tuvaluans came to be on their islands in the first place. You may now have some idea of how they got there, but we have not really considered the question of why. Why do you think the distant ancestors of the people who eventually arrived in Tuvalu (most likely after hundreds of years of island-hopping) left their original homelands?

Hau'ofa (1993) and other scholars familiar with the traditions of Pacific seafaring present a good case that sheer adventurousness has played a large part in Pacific voyaging. Yet this claim refers to people who have had thousands of years of experience in deep-water sailing and navigation. It may not be so useful in accounting for those first forays into the ocean, away from the sight of land.

Perhaps some pressure or stress helped to push people seawards – possibly a shortage of land or other resources. Something along these lines has been suggested by Nunn (2003), and his explanation turns out to have rather a surprising relevance to contemporary islanders threatened by the effects of climate change. Nunn proposes that it might have been the stress brought on by changing climate that first propelled people out into the ‘blue water’ of the Pacific.

It is, of course, very difficult to piece together the motivations of people who lived thousands of years ago, and so speculation is called for. Nevertheless, based on a combination of evidence from archaeology and climatology, Nunn (2003) propounds that rising sea levels caused by a cycle of long-term climatic warming may have been a major push factor.

In the aftermath of the last ice age (about 10,000 years ago), the receding and melting of glaciers would have led to rising sea levels all around the world, with serious repercussions for people who had settled into agricultural life on coastal lowlands. One likely area of displacement, a region where it is known that there were early farmers, was the coasts of East Asia, especially on the rich alluvial plains around the mouths of large rivers like the Huanghe and Yangtze in present-day China. Some of these people, Nunn suggests, may have headed out into the ocean: ‘In this scenario the first true Pacific Islanders were “environmental refugees” rather than the bold, curious adventurers they are sometimes portrayed as having been’ (Nunn, 2003, p. 220).

However, it is unlikely that everybody left the coasts and set out into the oceans, so we might amend Nunn's view and say that they may have been bold and adventurous as well as being under pressure! If we keep in mind, as Nunn encourages us to do, that those setting out into the Pacific had no way of knowing what the world into which they were heading was like, then it is conceivable that those people who ventured out into the open ocean may have been hoping to find places where the sea was not rising (Nunn, 2003, p. 22).

Another way to express this would be to say that as a certain territory came under pressure, or began to destabilise or come undone, some people began an outward flow that would eventually lead them into making new territories. As Lynas (2003) observed in Reading 1A, under current conditions of climatic change the world ‘seemed to be unravelling’. One implication of Nunn's (2003) view is that the world may have also felt like it was ‘unravelling’ in the past, perhaps many times before. Nunn's argument makes a strong claim for the ongoing impact of climatic change on the peoples of the Pacific. For the people of Tuvalu, and many other low-lying islands, climate change indeed appears to have been decisive in the past. As Nunn explains, it was only after a colder period 2000 or 3000 years ago, with resultant falls in sea level, that the land that became Tuvalu surfaced from the ocean, enabling the accumulation of sand and gravel, and coral growth that helped make the islands.

Subsequently, from around AD 750 to 1250, the Pacific experienced a phase of gradual warming known to climate change scientists as the ‘Medieval warm period’ (Nunn, 2003, p. 223). As temperatures rose, so too did sea levels. Rising sea levels would have brought salt into the fresh water beneath the ground of many islands, as it is doing at present, while declining rainfall would have increased aridity. Although such conditions would have impacted harshly on island life, there may have been some compensation as clear skies and decreased storminess seem to have encouraged long-distance voyaging – increasing inter-island contact and leading to the discovery and settlement of new islands.

Around AD 1300, this warming came to a close and a period of rapid cooling followed. In Europe, this was known as the ‘Little Ice Age’. Global cooling meant more water locked up in ice as well as a general lowering of sea water temperatures worldwide, with the result that sea level may have fallen by as much as 1.1 m between the thirteenth and sixteenth centuries. There are paintings and prints from this period of English history showing people ice-skating or walking on a frozen River Thames. While this spell of coldness may have caused considerable hardship in Europe and other temperate regions, global cooling had rather different implications for the island peoples of the Pacific. Nunn (2003) describes the likely effects of what he calls the ‘AD 1300 Event’:

> Almost all Pacific Islanders at the time lived along island coasts and, although they may have had inland food gardens, they would also have depended on crops (including coconuts) growing on coastal lowland areas. As sea level fell, so water tables fell, and many such crops would have grown and yielded less well. More importantly, these people would have been accustomed to acquiring food from nearshore coral reefs but when the sea level fell the most productive parts of these reefs would have been exposed above sea level and would have died. Likewise these people would have routinely exploited lagoonal resources for sustenance or trade, but when the sea level fell and exposed the surfaces of the nearshore reefs, this would have inhibited lagoonal water circulation resulting in turbidity and sluggishness, which in turn would have caused a deterioration in the health of lagoon ecosystems and a decline in their organic productivity.

> The cooling and the increased storminess during the AD 1300 Event would have exacerbated many of the effects described above, largely through increasing stress on various food-producing ecosystems. It is thought that within 100 years of the AD 1300 Event, the food resources readily available to coastal dwellers in the reef-fringed Pacific Islands fell by around 80 per cent.

> (Nunn, 2003, pp. 223–4)

It is difficult to piece together all the factors involved, but such changes are likely to have brought great stress and loss of life: what we might describe as a serious undoing and remaking of many Pacific island territories. Moreover, in the case of very low-lying islands like Tuvalu there was no option, as there was on larger islands, of moving inland to exploit new resources. One redeeming factor is that falling sea levels would have brought new islands and atolls to the surface, some of which were then settled (Nunn, 2003, p. 224). Such islands, however, would have been poor in resources, having not had time to develop a rich web of living organisms.

Nunn's (2003) research reminds us that climate fluctuates and varies, even without human impact. More than this, the evidence he presents makes the point that climate changes not just over millions or thousands of years, but sometimes over timescales short enough to be registered in human lifetimes or in memories passed between generations. While changing flows of air and water might currently threaten island territories like Tuvalu, we need also to consider that earlier changes have not only disrupted island life before, but may have played a pivotal role in initiating the exploration of oceans and settlement of islands. Changing climate contributes not only to the unmaking of islands, but also to their making.

We have seen that there were very different, but nonetheless parallel, experiences of cooling in the AD 1300 Event in northern temperate countries like Britain and on the tropical islands of the Pacific. It is worth considering what the implications of this might be for the way we imagine our world. In both places, at the same time, climate change exerted considerable stress. Yet, from a human perspective, these far apart territories did not share a common world. It was only towards the end of the cold phase that the first European explorers ventured into the Pacific Ocean, and it was not until several centuries later that contact between Europeans and Pacific islanders became ongoing and sustained. Therefore, in the imaginary geographies of the era – of both Europeans and islanders – it was not yet possible to experience climate change as a fully global phenomenon.

Nonetheless, as we can see through the lens of a contemporary world view, climate change in the AD 1300 Event and all other major fluctuations in climate are fully global phenomena. Climate in temperate Europe and climate in the tropical Pacific was as connected and mutually implicated then as it is now, as it has been for the estimated 4.5-billion-year existence of our planet. Thus, knowledge of human-induced climate change may be contributing to a new experience of entanglement between faraway people or places, but in another sense – a purely physical sense – our planet has always already been fully globalised.

An understanding of the globalised climatic flows that impact on oceanic islands adds further weight to the idea that the making of territories is a much more than human process and, indeed, a much more than biological or organic process. This awareness of forces and energies that are literally larger than life becomes even more pronounced when we turn to the physical processes that bring islands into existence.

OpenLearn - Climate change: island life in a volatile world
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