1According to the recent United Nations Rio+20 Earth Summit, one of humankind’s greatest challenges for the twenty-first century is to make it the “sustainable century”.1 And as concerns have grown over the degradation of natural systems on which human life depends, so has the study of environmental history, bringing a much-needed historical perspective to discussions about sustainability. Historians often use the first Earth Day, 22 April 1970, as a “turning point” that marked the entry of modern environmentalism into the political mainstream.2 In a volume concerned with the implications of periodisation and “turning points” in history, it can also be used to highlight that environmental history, which deals with the complexities of human-nature relations over time, was born out of the green activism of the 1960s and 1970s. With its roots in the environmental movement, scholars in the field often aim to make their work relevant for policy-makers (although there is less political engagement among practitioners today than there was fifty years ago).3

2From the outset environmental history has been an interdisciplinary endeavour, bringing together scholars from the humanities and natural sciences. This is because it is only possible to write nature into historical narratives, to make climate, soils, forests, rivers and oceans “co-creators” of our histories, by using both written documents and scientific data.4 And as one of the youngest fields of historical study, it has brought fresh thinking about, and approaches to, space and time. Given that political boundaries and ecological boundaries rarely coincide, in environmental history the familiar organizational framework of the nation-state is not always an apt unit of analysis. As “everything connects” in nature —climate change illustrates this point well— adopting a “Big History” approach often makes more sense from an analytical point of view. National, regional and local histories remain important, however, as data are rarely gathered at a global level. Environmental history can be written on any scale, and the fast-growing literature in this new field —on themes such as biological exchanges, population growth, energy use, and the ecological impacts of agriculture, imperialism and industrialisation— has allowed scholars to weave the various threads of national, regional and local narratives together to produce work at the macro-scale.5

3Systems of periodisation in environmental history are often defined by long-term natural processes, rather than the conventional political markers of nation states. For example, important works such as Anthony Penna’s The Human Footprint (2010) begin with the origins of the earth itself, while Ian Simmons’s An Environmental History of Great Britain (2001) takes the end of the last ice age as its starting point.6 Timescales routinely encompass millennia, challenging historians to engage with chronologies that reduce the human lifespan to the blink of an eye. This, however, is not a wholly new departure. For example, the pioneering work of Fernand Braudel on the Mediterranean world, which directed attention to the importance of human-environment relations and emphasised the long-term view of history, was undoubtedly influential in shaping approaches to environmental history. Now a well-established field of study, “environmental history is mostly played out over the longue durée”.7 Its growth has seen a revival of historical interest in looking at large geographical areas over long time periods.

4Periodisation is about managing time; a practical concern that helps historians to bring “meaning, order and coherence” to the past. Over the centuries, as Ludmilla Jordanova has pointed out, historians have developed comfortable and conventionalised forms of division, based on rulers and dynasties, types of government, cultural styles, major events, or by decades, centuries or epochs, that “we barely think about”. British examples include: the Tudor, Georgian, and Victorian periods; the “Roaring Twenties” and the “Swinging Sixties”; the Age of Empire; the“long” eighteenth century and the Interwar Years (1919-1938). They tend to stifle fresh thinking.8 Simmons apart, to date most scholars writing British environmental history have tended to follow existing practice.9 But when it comes to human interactions with nature, where change often needs to be studied over very long time-spans for significant trends to become apparent, new ideas about periodisation are beginning to emerge that challenge old conventions. Indeed, debates over the key eras and pivotal points of environmental history have recently started to attract considerable scholarly attention. In an attempt to better structure the sub-discipline, practitioners have suggested numerous “turning points”, from the domestication of fire through to the 2007 Arctic sea ice minimum, that stretch back over many millennia. Joachim Radkau, wary of their potential for multiplication, has posed a crucial if straightforward question for those engaged in this endeavour: “Is this concept useful for doing research and does it help to find out something one doesn’t know in advance?”10 In this chapter, I will set out a series of “turning points” that should prove useful in contextualising the goal of making this the sustainable century, especially in relation to climate change. It will also provide an unexpected interpretation —at least for some— of Britain’s industrial past.

5One of the challenges for scholars writing global environmental history is to identify big themes, such as population pressure on resources and the growth of cities, which both stretch across long timescales, and that apply to human-nature relations in different parts of the world. Here I will concentrate on one particular theme, the history of energy regimes; a topic which connects with many other areas of historical change (as we shall see). Rolf Peter Sieferle and Vaclav Smil were among the first to highlight the role of energy systems in shaping world history. Building upon these foundations, recent work by scholars such as Alfred Crosby, Ian Simmons, and Edmund Burke III has suggested a persuasive, environmentally-informed periodization of history on a global scale, based on changes in energy sources and consumption.11 Rather than the familiar, overarching narrative of progress that links the invention of agriculture, classical Greece and Rome, the Renaissance and Enlightenment, the Industrial Revolution and modernity in an “ascendant trajectory”, instead they see the Industrial Revolution as a decisive break with the past and in human relations with nature. It is seen as a key “turning point”; but it is a misstep that leads to growing environmental problems and ultimately into an “unsustainable dead end”.12 This periodisation frames a counter-narrative which is the antithesis of “whiggish” history, and it exposes the previously hidden environmental costs of “progress” to view.

6In common with much “big history” scholarship, the focus on humankind’s acquisition and use of energy over the longue durée significantly changes our perspective on the past. Most life on earth was, and is, dependent on harvesting energy from the sun, and Figure 1 (below) provides a radically different chronology for human history than the traditional framework outlined above. At first glance, it seems to lack the complexity and nuance demanded by some for periodisations of environmental history today.13 It is a clear division between what Burke III calls “The Age of Solar Energy” or what Braudel called the “biological ancien regime”, based on renewable resources, which dominated until being superseded by the “The Age of Fossil Fuels”, based on non-renewable resources. Delving deeper, however, it is a system of periodisation that also frames a complex story of “slow evolutionary change and sharp revolutionary departures”.14

7The process of photosynthesis, by which energy is captured and stored by plants, is central to life on earth, and to this system of periodisation. When Homo sapiens first started out around 200,000 years ago, it was as hunter-gatherers. They lived off the land, harvesting energy stored from the previous year (directly) by consuming food plants; over several years (indirectly) by consuming animals; and over decades (sometimes centuries) in the wood that they burnt in cooking and heating fires.15 Indeed, the harnessing of fire by humans is itself a key “turning point” for environmental historians such as Stephen Pyne.16 It was used not only for cooking (which improved diet, nutrition and survival chances), but also as a tool to reshape the landscape. For example, anthropogenic fire was used to create clearings in forests that facilitated hunting (and might even have marked out territorial bounds). The apparent success of hunter-gatherers in using natural resources wisely over millennia, and allowing underlying environmental support systems to remain in good working order, has generated considerable scholarly debate as to whether such groups were the “first ecologists” (and hence possible role-models for a more sustainable future).17 Whether or not hunter-gatherer societies, with their intimate knowledge of local ecosystems, were really “prudent predators” is still open to question. The arrival of humans in the Americas (14,000 years ago) and Australia (50,000 years ago), for instance, is believed to have led to the extinction of many large mammal species.18 But their basic technologies, highly mobile lifestyles, lack of demand for material possessions, and low population levels meant that their ecological impact was relatively light. Humans only numbered around 4 million in total worldwide when warmer conditions following the last ice age encouraged the transition to settled agriculture.19

8The main stages of human history set out in Figure 1 show our evolution as a species from simple to complex harvesters of energy. The different stages of development overlap to some extent: new ways of acquiring and using energy are added, while older techniques decline in importance —but do not wholly disappear. Over millennia humankind came to live on the land as farmers, rather than off the land as hunter-gatherers.20 Humans domesticated a relatively small roster of plants and animals, such as wheat, oats, rice, cattle, sheep and horses, so that sources of food, fibre and muscle power would be close at hand. In ecological terms, humans joined in “unconscious alliance” with these species and each became dependent on the other. Arguably, domesticated organisms “chose us as much as we chose them”.21 And since settled agriculture first emerged in the Fertile Crescent of the Middle East around 11,000 years ago, hunter-gatherer societies have been gradually pushed to the margins. Representing “at least 90 per cent of human evolutionary history”, only small numbers of hunter-gatherers survive today.22

9Hunter-gatherers needed large territories to exploit, about 10 square miles per person depending on the environment and resources available. Early farmers exploited the sun more efficiently and the land was made to feed many more mouths, with only around a tenth of a square mile required to provide the daily dietary needs of a single person.23 The “Neolithic food revolution” has been described as one of the most significant breakpoints in humankind’s history, and the development of sedentary farming secured more of the products of photosynthesis —through plant cultivation and animal husbandry— for use, greatly increasing the carrying capacity of the land.24 From its beginnings in the Middle East, the archaeological record shows that the transition from food-gathering to farming also happened independently in Southeast Asia (date uncertain), China (9,000 years ago), central Mexico (6,000 years ago), Sub-Saharan Africa (5,000 years ago), South America (5,000 years ago) and North America (4,000 years ago). According to William Ruddiman’s controversial hypothesis early agriculture, particularly rice irrigation, livestock rearing and deforestation, may even have prevented a return to ice age conditions by significantly raising levels of methane, a powerful greenhouse gas, in the atmosphere. The move to a sedentary agricultural lifestyle did have some disadvantages, however, as the health of early settled populations suffered initially. Eurasian agriculturalists, living in close proximity to domesticated animals, were exposed to infectious diseases that jumped species, such as smallpox, measles and influenza, only slowly building up resistance.25

10Food surpluses generated during the early agrarian age, with the help of techniques such as selective breeding and irrigation systems, allowed the emergence of the first agrarian civilisations and city-states along the banks of the Tigris-Euphrates, Indus and Nile river systems. Although few in number these cities and urban-like developments became important centres of growth, trade and exchange.26 Ancient Rome, the archetypal imperial city, imported a wide range of goods and foodstuffs through trade networks that spanned Italy, empire and the wider world. Both water-borne and road transport brought, for example, silks, cottons and spices from China and India; grain from Egypt, Tunisia and Sicily; olive oil from Libya and Spain; and timber from the Alps and Lebanon. But it required a new system of global maritime trade —following what Crosby called the Columbian Exchange of 1492— for humans to take full advantage of the agricultures that had developed at different times in different regions of the world.27

11The Columbian Exchange is one of the few markers of change in environmental history that has entered the historical mainstream, and the impacts of Columbus’s 1492 voyage are difficult to overestimate. Restoring contact between the previously isolated Old and New Worlds exposed millions of people to unfamiliar disease-causing microbes to which they had no acquired immunity. Deadly “virgin soil” epidemics of smallpox, influenza and other Eurasian and African diseases reduced New World populations to a fraction of their former numbers. Although figures are disputed, academics generally agree that “microbial unification” caused very high levels of mortality: between 50 per cent and 90 per cent in the Americas. It was one of the biggest demographic disasters in world history.28

12However, in an energy context, bringing together the different sets of plant and animal species farmers had been working with on opposite sides of the Atlantic and Pacific enriched the food supply and stimulated production. But, as Figure 2 demonstrates, it was something of an uneven process.

13For example, very few American animal species, most notably the turkey, were domesticated for food. But from the sixteenth century New World staples, such as maize, manioc, and potatoes, were widely adopted by farmers in Africa and Eurasia. European traders, for instance, brought sweet potatoes and maize to China in the mid-1550s, and they quickly became primary crops in many areas. Where return passages are concerned, wheat fields, sugar plantations, cattle ranching and sheep herding soon spread throughout what Crosby called the “neo-Europes”, temperate zone regions in Argentina, southern Brazil, parts of Chile, and much of North America. The diffusion of highly productive new crops as a result of the Columbian Exchange —a process that is still in motion today— provided the nutritional foundations for sustained population growth around the globe as communication and transport networks improved and extended.29

14As Figure 3 shows, between 1400 and 1800 there was a more than fourfold increase in the Chinese population; a threefold increase in the population of Europe; the population of India more than doubled; as did the population worldwide. The exceptions were in Latin America, which took centuries to recover from what has become known as the “Great Dying”, and in sub-Saharan Africa, hit hard by the slave trade from West Africa, which provided labour for new plantations in the Americas.

15The great increase in world population during the late agrarian age began to push the solar energy regime to its limits, as humans exploited a wider range of crops. The energy harvest available was still tightly constrained: agricultural societies had to meet their needs for food, fuel, clothing and shelter from a finite acreage of farmland and woodland (with some limited assistance from windmills and waterwheels in suitable locations). Even with good farming techniques and high-yielding crops, recurring energy and resource shortages impeded development. For example, clearing forests for agricultural use reduced the amount of wood available for fuel and construction. As long as economies were mainly based on muscle-driven agriculture and biomass energies their productive capacity remained relatively low, while the share of the population who were poor and rural remained high.30 As people were unable to capture and convert into useful forms more than a fraction of the energy available on earth, within the biological ancien regime there were always going to be limits on both the size of populations and the productivity of the economy. The switch to fossil fuels during the industrial era changed all that, and for the first time humans broke free of the limits to growth set by the “virtually instantaneous energy flows” of the solar regime.31

16The increase in global population saw more forests cleared for agricultural purposes, and the price of fuelwood rise sharply as supplies became scarce. And by 1800 western Europe, China, Japan and parts of the Americas were facing an energy crisis. Although coal had been used for iron production in China during the Han dynasty (200BCE-220CE), the “great transition” to this form of fossil fuel began in Britain during the sixteenth century, which was most seriously affected by wood shortages. The price of firewood in Britain had increased sharply between1500 and 1630, by around 700 per cent.32 Coal first supplemented the national wood supply, and then became the predominant source of fuel as Britain’s energy use intensified during the early stages of the Industrial Revolution. Britain consumed more coal per capita than any other country in the world until 1905, when the United States took over as the largest consumer of energy.33

17The Industrial Revolution is a concept that has been brought into question recently by some economic historians, who insist that growth rates were “evolutionary” rather than revolutionary.34 But viewed from an energy perspective, it represents perhaps the most revolutionary break with the past. The invention of an efficient steam engine in the late eighteenth century, the electric motor and the internal combustion engine in the nineteenth century, and the gas turbine in the early twentieth century, lessened people’s dependence on wood, water, wind and muscle-power and made possible the exponential growth of economies and populations. These technological innovations, prime movers of the Industrial Revolution, promoted and required the harvesting of subterranean coalfields, oilfields and gasfields. Hitherto unimaginable stores of energy, the results of millions of years of photosynthesis, suddenly became available for human use: a move away from renewable energy resources to non-renewables, and a decisive break with past. Drawing on energy stocks deposited in prehistory, the Industrial Revolution allowed modern societies to replace animate power with mechanical power and accelerated the pace of resource extraction, production and consumption.35 And as Burke III has noted, “Previously, the overuse of resources was readily apparent: now resources could be consumed without regard for the environmental consequences”.36

18In the booming cities of the Industrial Revolution (originating first in Britain, then spreading throughout Europe, North America, Japan and the wider world), factories produced a growing range of affordable goods, and the jobs they provided brought a measure of affluence for most urban workers. here was an increase in consumerism after 1850, symbolised by the department store, radiating out from the cities of northwestern Europe and the United States. In agriculture, labour-saving machinery released rural workers from the land, and from the early twentieth-century artificial fertilisers derived from fossil fuels (consumption increased from 2 million tonnes per annum to 137 million tonnes per annum between 1900 and 2000) brought higher and more reliable crop yields, which in turn underpinned ongoing urban-industrial growth.37 he Industrial Revolution decisively shifted the balance of power in the nature-human relationship. In the last two centuries, technological innovation and the rising use of fossil energy have allowed humans to shape their environments more than they have shaped us. Energy use increased around 40-fold worldwide between 1800 and 2000, and efficiency gains through innovation often led to more consumption (rather than to expected energy savings).38

19It was the mid-twentieth century, however, that saw what has been termed “The Great Acceleration” by Will Steffen, Paul Crutzen and John McNeill, with cheap energy prices rapidly increasing the pace and scale of human enterprise. During the early fossil-fuel era, growth had been disrupted by two world wars and economic depression. But after World War II, lower prices for fossil fuels —coal, gas, electricity, and oil, especially petroleum— saw a surge in energy use. Since 1950 the global economy has increased 15-fold; the world’s population has more than doubled to over 7 billion; motor vehicle ownership increased from about 40 million to over one billion today; and the proportion of the world’s population living in towns and cities has now passed 50 per cent.39 Modern energy technologies help to support unprecedented numbers of people and unprecedented levels of material consumption: but the pressures they place on the planet’s ecosystems are now becoming unsustainable.40

20Human enterprise has altered not only the face of the earth, but also the flows of key elements through the biosphere, with serious ecological consequences. Increasing freshwater withdrawals from rivers and lakes for agricultural, industrial and household use, for example, have disrupted the hydrological cycle. At times, the flows of major rivers such as the Nile in Africa, the Colorado in North America, and the Yellow River in China are so reduced that they no longer reach the ocean. During the last fifty years, the overuse of factory-produced artificial fertilisers has altered the cycles of nitrogen and phosphorous in the biosphere, far outweighing natural releases of these nutrients, resulting in serious pollution problems such as eutrophication (river, lake, estuarine and coastal waters become too nutrient-rich and deoxygenated, causing dramatic algal blooms and fish mortality). Their use also disrupts the microbial activity that builds healthy soils, and masks underlying problems of accelerating erosion: and soils are not a renewable resource in terms of human life-spans.41

21However, the increase in the amount of carbon dioxide in the atmosphere, due primarily to our heavy use of fossil fuels, is potentially the most damaging human-induced environmental change, profoundly altering the global carbon cycle. Ice core data show that pre-industrial levels of carbon dioxide had remained stable for thousands of years at around 280 parts per million. The combustion of fossil fuels since 1800 has increased CO2 levels to above 390 parts per million globally, with most of this increase coming after 1950 (well above the 350 parts per million mark that many scientists say is the highest “safe” level for carbon dioxide in the atmosphere). Concentration levels exceeded the symbolic 400 parts per million threshold at several Arctic monitoring stations for the first time in 2012. If current rates of carbon dioxide emissions continue unchecked (and according to the World Meteorological Organisation atmospheric concentrations of CO2 are now at record levels), then by the end of the twenty-first century global temperatures may rise to levels not seen for 2 million years.42 Unless an effective global agreement can be brokered to greatly reduce carbon dioxide emissions, then an estimated temperature rise of between 1.8 and 6.4 degrees Celsius will see “natural” disasters such as storms, floods, heatwaves, droughts, and forest fires become more frequent and severe. Global warming is already responsible for around 300,000 deaths per annum, and it brings disease, hunger and poverty to millions, mainly in developing countries. Rather than the twenty-first century becoming the sustainable century, some commentators are now talking about the earth facing a “century of disasters”.43

22Finally, environmental history, as well as challenging historians to think back over much longer timescales, and across disciplinary and geographical borders, also stretches time —moving beyond “normal scales” of history.44 Engaging with energy, climate, and sustainability issues, for example, not only makes us think differently about the past, but also about the present and future. Most carbon dioxide added to the atmosphere remains there for about 100 years, although a significant proportion (20-40 per cent) persists for many thousands of years into the future. Anthony Penna has pointed out that the emissions from early twentieth-century cars, power plants and factories, such as Henry Ford’s model T automobiles, continue to affect the carbon cycle. The question of responsibility for historical CO2 emissions —the United States contributed around 30 per cent of emissions between 1850 and 2000, closely followed by the combined emissions of western Europe— is one of the key obstacles to negotiating a global climate deal today. Developing countries like China (its contribution was 7 per cent) and India (just 2 per cent), with low per capita emissions and limited historical responsibility for high levels of greenhouse gases, are unwilling to act on climate change as they seek to grow their economies and improve living standards.45 Nuclear power has become a significant source of carbon-free energy globally since World War II (accounting for around 5 per cent of the world’s energy supply), but the problem of managing nuclear waste has still not been solved satisfactorily. Spent nuclear fuel contains long-lived radionuclides, such as plutonium and uranium, which remain extremely dangerous to life and health for tens of thousands of years.46 Green issues, then, raise important questions about intergenerational as well as social justice, as the decisions that we make today on climate and energy use will affect numerous generations to come.

23The kind of environmentally-informed periodization of energy history that I have outlined here, perhaps most importantly, helps to show that there is a fundamental mismatch between the scales at which human and natural systems are organised: and modern governments —with their short-term national interests— are not proving to be particularly adept at planning for long-term sustainability on a global scale. The Industrial Revolution was the decisive breakpoint, when the human species began to lose touch with the land, shattering the constraints of the old solar regime. Governments are now showing more interest in developing renewable energy sources, such as biofuels, wind turbines, tidal barrages and photo-voltaic cells, but the consumption of cheap coal and other fossil fuels is still rising worldwide (especially in China).47 According to John McNeill, our insatiable appetite for energy saw us consume more in the twentieth century than in the whole of human history before 1900. And because of our extraordinary capacity to modify the natural world to meet our needs, the climate scientist and Nobel laureate Paul Crutzen has suggested assigning the term “Anthropocene”, the human epoch, to describe the present period of the earth’s history. The precise date of the onset of the Anthropocene is debatable, but Crutzen pinpoints James Watt’s invention in Britain of the double-acting steam engine in 1784.48