IT GOES WITHOUT saying then that tropical forests are up against it. So too are their human inhabitants, according to the latest “State of the Tropics” report. In 2020, almost half the world’s total human population lived in the tropics. And by 2050 over half of the world’s population will call the equatorial regions their home. The future of our species as a whole undoubtedly relies on what happens here in the years to come. Many of these people will also increasingly live in cities. By 2050, 6.3 billion of the world’s human population will live in an urban area. The tropics account for over half of this planned increase and have witnessed growing rural-to-urban migration between the late twentieth and early twenty-first centuries, with over 1.5 billion people currently living in tropical cities. Growing economies and the social, commercial, and health opportunities provided by urban networks are driving these trends, particularly in Southeast Asia. Indonesia’s urban population, for example, grew from 32 million in 1990 to nearly 150 million by 2018. Nearly three-quarters of the populations of Central America, South America, and the Caribbean are already living in urban areas. Just under one-quarter of the tropical urban population lives in slums with incredibly poor living conditions, which have characterized regions experiencing rapid urbanization since the nineteenth century. These informal settlements are broadly declining, thanks to rising wealth and settlement-improvement programs, and often offer access to diverse income opportunities and cultural connections. Nevertheless, ensuring the sustainability and inclusivity of cities in the tropics, including moves toward “green space” integration, is a major United Nations concern in the context of environmental conservation and human living standards.9
Growing populations will require growing access to food. In Chapters 10 through 13, we followed an intensifying conflict between tropical forests and expanding agricultural, pastoral, and extractive land use. The tropics are home to 39 percent of the planet’s agricultural land area, and while this land is used to support food security for the region’s growing population, it also continues to feed the desires of the export market, as it has since at least the seventeenth century. Cropland in tropical countries expanded by 48,000 km2 per year between 1999 and 2008, with Nigeria (10,259 km2), Indonesia (5,826 km2), Ethiopia (5,405 km2), Sudan (5,227 km2), and Brazil (4,205 km2) showing the greatest areas of annual expansion. Yet expansion of agricultural production has not necessarily expanded the tropical food base. Islands in the Pacific and Indian Ocean have actually seen a reduction in agricultural land due to pressures to expand tourist and urban infrastructures. Similarly, the rising proportion of agricultural land used for biofuels or cash crops for export may benefit local incomes but not food security. Foreign demand has also primarily driven increases in meat production in the tropics (a rise of 76 percent between 2010 and 2017), with Brazil, India, and Australia acting as particularly significant meat exporters to China, the United States, Japan, Europe, and the Middle East. The economic benefits of these changes may not be reflected in local tropical sustainability. These problems are particularly acute because remote sensing and mapping models of soil erosion predict that tropical Africa, South America, and Southeast Asia will see increasingly poor, unstable soils over the course of the twenty-first century. The inhabitants of the tropics are going to face increasingly difficult decisions between exploiting imbalanced economic export markets to improve incomes and developing more productive, sustainable subsistence agricultural systems to meet their own nutritional requirements.10
Extreme poverty is defined as “severe deprivation of basic human needs, including food, safe drinking water, sanitation facilities, health, shelter, education and information.”11 In positive news, globally, 1 billion fewer people were living under these conditions in 2015 than in 1990. Nevertheless, the majority (85 percent) of the remaining more than 100 million of the world’s population experiencing extreme poverty live in the tropics. Population growth, conflicts, and a complex interplay of political and economic factors mean that in some tropical nations the proportion living under such conditions is actually increasing. Just five nations—Nigeria, the Democratic Republic of the Congo, Ethiopia, India, and Bangladesh—house 50 percent of the human population living in extreme poverty the world over. In terms of “moderate poverty,” where basic needs are met, but just barely, and people earn less than $3.20 per person per day, the tropics have also seen much more modest improvement: 1.3 billion people live in moderate poverty in the tropics, double the number for the rest of the world. As we saw in Chapter 13, poverty is a major issue for tropical forest conservation and sustainability, as populations and governments seek to balance demands for food, water, and income with environmental impacts. The prevalence of poverty across the tropics is widely recognized as a product of colonial processes that continue to shape economies based on agricultural systems with large, poorly paid workforces, infrastructural imbalances, a reliance on foreign investment, and colonially drawn boundaries that can catalyze political and cultural conflicts. However, this has not stopped nations and companies in Europe and northern North America from continuing to exploit the situation, while simultaneously releasing more than their fair share of emissions into the atmosphere, which will again disproportionately affect the livelihoods of tropical residents.12
Climate change is already beginning to alter and destroy the lives of many people in the tropics. Climate models show that human-induced warming had already increased the likelihood of extremes in precipitation and temperature occurring in the tropics by 2010, and extreme weather events are likely to only become more acute and more frequent as the twenty-first century continues. Changing precipitation and water runoff modeled under global warming scenarios of 1.5°C to 2.0°C indicate increased flooding in South Asia, Southeast Asia, and the western Amazon, with some studies suggesting that fifteen of the twenty most impacted nations will be in tropical or subtropical regions. Many of the same regions, as well as other areas in the subtropics and tropics, will face increasingly frequent and intense drought periods over the course of the twenty-first century. These changes can have major impacts on human populations. For example, in Malaysia rice makes up 98 percent of current cereal production. It is estimated that for each 1°C rise in temperature, rice yields will decline by 10 percent, while wet rice systems may become increasingly unsustainable in the face of growing drought conditions. Meanwhile twenty-first-century flash floods and landslides have resulted in mass destruction and loss of life in cities such as Vargas in Venezuela. Growing storms, cyclones, and hurricanes are also battering the tropics more frequently. In 2017, Hurricane Maria killed over 3,000 people and caused $91.61 billion worth of damage in the northeastern Caribbean, and this was just one storm in a hyperactive Atlantic hurricane season. Rising sea levels represent a slower but eventually more permanent climate-based change to tropical livelihoods. Estimates project that an increasing intensity and frequency of storms and floods, sea level rise, and drought and desertification will together create around 200 million climate refugees worldwide in the next fifty years and perhaps as many as 700 million (nearly one-tenth of the world’s current population).13
Tropical deforestation is also causing a number of public health issues. Tropical forest edges have proven to be a major petri dish for pandemics. Roughly 1.7 million viruses exist in mammals and birds around the world at any one time, though a minute fraction is known and properly described. Tropical forest edges provide the greatest opportunity for humans and their close animal companions to come into contact with these significant epidemiological reservoirs. Deforestation and forest fragmentation, for logging or infrastructural development, create longer and more ragged forest edges, where growing numbers of humans and domestic animals become interspersed with populations of wild animals, priming a large human host for viral outbreaks. Hunting for bushmeat or medicinal trade further expands opportunities for contact. In fact, deforestation and human exploitation of tropical wildlife have resulted in many of the major disease outbreaks of the last tw
o decades. The 1980s emergence of HIV has been linked to bushmeat hunting in the Democratic Republic of the Congo. Outbreaks of the incredibly deadly Ebola virus in West Africa, which killed over 11,000 people between 2013 and 2016, have been linked to a single human contact with a bat colony. Bats are thought to be particularly prominent reservoirs of disease and feed closer to human settlements when their forest homes are disturbed. They are also thought to be the most probable original carrier of the SARS-CoV-2 virus that causes COVID-19, which likely began as a product of human-wildlife interactions in the humid subtropics of China. It is predicted that ongoing deforestation and fragmentation in the tropics in the twenty-first century will only increase the probability of highly virulent diseases making their way into human populations.14
Another challenge facing tropical communities seeking more sustainable livelihoods is the loss of Indigenous and traditional knowledge. The tropics are home to a staggering amount of human cultural diversity, including 80 percent of all living languages. As we have seen, local communities around the tropics have long histories (and indeed prehistories) of recognizing ecological thresholds and dynamics, performing sustainable agroforestry and farming practices, and incorporating new crops, technologies, and settlement patterns into their tropical environments. For example, Ifugao communities in the Cordillera Mountains of the Philippines have land rights laws, upland cultivation practices, knowledge of soil and water conservation, and forest stand management strategies, collectively known as muyong, that are critical for forest maintenance and biodiversity protection. Indigenous languages can be particularly crucial for passing on knowledge: people speaking the Indigenous Huastec language in western Mexico show more diverse and evenly shared knowledge of tropical plant use than Spanish-speaking Indigenous populations. However, Indigenous populations are currently some of the most marginalized groups within the tropics, facing higher rates of disease, higher child and adult mortality, and significant social disadvantages. Their languages are also disappearing, as young Indigenous people are integrated, often forcibly, into national capitalist economies and education systems. These losses represent a major threat, particularly in light of the fact that Indigenous populations and other local smallholders are crucial to the development of balanced, sustainable approaches to tropical forest use and conservation. This is especially the case given that over one-fifth of the significant portion of the world’s carbon stored in tropical forests lies on land belonging to or claimed by Indigenous communities.15
YOU MAY FEEL that this concluding chapter has so far resembled the nightmare international newsreel you are fed up with scrolling through on your smartphone, tired of hearing coming over the airwaves, and thoroughly done with watching on your television. But I am asking you to keep reading: your life is irrevocably intertwined with tropical forests. Even if you struggle to place yourself in the shoes of inhabitants living at the “ground zeroes” of tropical forest sustainability, you cannot get away from the fact that, before long, these problems will have made their way into your back garden. Increasingly seasonal, unstable soils and watersheds will reduce the productivity and availability of cash crops (e.g., rubber, oil palm, cocoa), staple crops (e.g., rice), and meat (e.g., sheep, goat, cow) in the tropics, reducing the size of exports making their way to reliant European, North American, and now also Middle Eastern nations. Furthermore, tropical forest deforestation and degradation will lead to continental and global changes in precipitation, temperature, and agricultural growing conditions. Finally, since the Carboniferous period, tropical forests, alongside the oceans (and, later, Northern Hemisphere forests), have played a major role in capturing carbon and regulating the degree to which global carbon emissions actually translate into rising atmospheric CO2. It is possible that higher temperatures could bring about faster tropical growth and more rapid fixation of CO2. However, as tropical deforestation and degradation, including through more frequent fire outbreaks, continue throughout the twenty-first century, particularly in swamp forest areas, the very real prospect of these environments becoming carbon sources rather than carbon sinks is a truly terrifying thought. The United Nations imperative to limit increases in global average temperature to below 2°C above preindustrial levels will drift increasingly out of reach. What happens in the tropics in the next century will shape what happens on our entire planet, be in no doubt about that.16
The predicted loss of tropical forest plant and animal species also represents a truly global problem, given their enormous contribution to planetary biodiversity. Assuming a complete loss, degradation, and alteration of all primary tropical forests by the year 2225, scientists have calculated that there will be a global species richness decline of approximately 44 percent for ant species, 30 percent for dung beetles, and 20 percent for trees. For the coming two centuries, predicted extinction rates for different global species groups vary between around 200 and 2,000 extinctions per million species per year, all relating to the loss of habitat in the tropics. As Professor Xingli Giam of the University of Tennessee has pointed out, these rates are between 2,000 and 20,000 times higher than we might expect under natural geological and biological conditions. Furthermore, they are “two or more orders of magnitude higher than extinction rates associated with four of the five previous mass extinction events,” including those of the Devonian, Ordovician, Permian, and Triassic.17 In fact, they are comparable to the rate predicted for the Cretaceous-Paleogene mass extinction that wiped out the dinosaurs. Put together, then, estimates project that the deforestation and degradation of tropical forests, not even mentioning the additional, likely contributions of human-induced climate change, will result in a sixth planetary mass extinction event at the end of the next two centuries. Just think about that for a second. The events unfolding around the equator today as we go about our daily lives are predicted to have the same, or greater, impact on the world’s biodiversity than geologically known catastrophes that took life on Earth to the very edge of the cliff face.18
The public health crises facing the tropics mentioned above have, in the past decade, also now very blatantly blanketed the world. Cases of the Ebola virus in Texas, in the United States, and Glasgow, in the United Kingdom, in 2014 showed the potential for this deadly disease to be carried beyond the African tropics, and outbreaks continued in the Democratic Republic of the Congo into 2020. The extratropical transmission seen for Ebola so far, however, pales in comparison to that seen as part of the ongoing COVID-19 pandemic. By the end of January 2020, the SARS-CoV-2 virus had spread around much of China, which rapidly went into a state of lockdown. Although recent studies suggest it may have made it to Europe as early as the end of December 2019, certainly by March 2020 the virus was transmitting between people in Europe and North America, with Italy and the United States becoming new centers of the outbreak. At the end of January 2021 there were more than 96 million globally documented cases of COVID-19, with more than 2 million deaths. Although many countries have managed to reduce cases, and a number of vaccines are now available, as I write this book, there is no rapid end in sight. The emotional, psychological, and economic damage caused by death rates, understaffed hospitals, abandonment of workplaces, the closure of schools, the decline in domestic and international travel, and reduced access to infrastructure and facilities is expected to be dramatic and long-lasting. Nevertheless, while this virus has already changed our lives forever, more, perhaps deadlier pandemics linked to human–wild animal contact in the tropics are likely to emerge as the twenty-first century wears on.19
Legacies of colonialism and imperialism met in Chapters 10 and 11 will also continue to shape the face of global economics, politics, and sustainability in the twenty-first century. Gross domestic product (GDP) has increased across the tropics between 1990 and 2018, but so too has its gap with the rest of the world. Paychecks sent home by diasporic workers make up significant proportions of the GDP of many tropical nations. Furthermore, debt has increased across the tropics since 2013, placing tropical
nations in a precarious position, particularly when external events such as pandemics require rapid responses. These issues might have traditionally seemed “far away” to you. However, they present challenges we will all have to deal with. Climate change is expected to have a particularly intense impact on the growing, impoverished inhabitants of the tropics, resulting in increasing numbers of “climate migrants” that nations across Europe, North America, and Australasia will have to contend with. To take one example, at the current pace of sea level rise, the people forced to migrate away from Bangladesh by the end of the century will outnumber all current refugees around the world. Western European and northern North American nations will also have to manage the challenge of reducing global carbon emissions (the majority of which they are responsible for) while respecting and offsetting the needs of tropical nations to grow and attain living conditions that many of their Northern Hemispheric counterparts have enjoyed for so long after half a millennium of colonialism.20
THE ABOVE MAY suggest that the situation is bleak. But it is necessary to underscore the urgency of the situation at hand. This does not mean that there is no room for positivity. The deep human history of tropical forests revealed by this book highlights the way in which societies have repeatedly adapted to change and challenges in the tropics. Indeed, this ecological flexibility may even define our species. However, we have somewhat lost our way. Global consumer demand, wealth inequalities, and political priorities continue to exert pressure on some of the habitats we can least afford to lose. This book has revealed two key avenues out of this dangerous cycle. First, whether it is Pleistocene hunter-gatherers encountering giant sloths in the Amazon or food producers experimenting in highland New Guinea, pioneering precolonial voyagers to uninhabited Pacific islands or water-tank-building urban dwellers in Sri Lanka, intimate on-the-ground knowledge of these ecosystems characterizes successful adaptations to tropical forests. Only if local smallholders and Indigenous populations are properly consulted and empowered, supported by detailed archeological, paleoecological, and historical records of past human management, can more beneficial, adaptable ways of living with tropical forests be enacted. Second, we must acknowledge that some of the greatest pressures facing tropical forests and their inhabitants today are a product of long-term colonial and imperial extraction that have enriched nations and social groups in Europe and northern North America and degraded tropical forest environments and local possibilities for economic growth. Moving forward requires that global consumers and governments recognize that they too must bear responsibility for what happens in these environments.21
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