This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Environmental Science. Please check back later for the full article.
In 1945, the Amazon biome was still mostly intact. The scars of ancient cultural developments in Andean and lowland Amazon had healed, and the impacts of rubber and other resource exploitation were reversible. Very few roads existed, and only in its periphery. In the 1950s and especially in the 1960s, Brazil and other Andean countries launched ambitious road building and colonization projects, largely driven by Brazilian geopolitical concerns. Interest in the Amazon became much more intense in the 1970s as forest loss began to raise worldwide concern. Construction of more and better roads continued at an exponentially growing pace in each following decade, multiplying correlated deforestation and forest degradation everywhere in the Amazon. A point of no return was reached when interoceanic roads crossed the borders of Brazilian-Andean countries in the 2000s, exposing the remaining safe havens for indigenous people and nature. It is commonly estimated that today no less than 18% of the forest has been replaced with agriculture and that more than 50% of the remaining forests are significantly degraded. Most deforested land, especially in Andean countries, is wasted or scarcely used. Oil, mining, and intense urban development, as well as intensive agriculture, spread serious water and soil contamination throughout the region. Logging, fisheries, and hunting gave rise to the successive commercial extinction of valuable species.
Theories regarding the importance of biogeochemical cycles had already been in development since the 1970s, however, in the late 1980s the dominant popular view on the environmental value of the Amazon “lungs of the planet” emerged. The confirmation of the role of the Amazon as a carbon sink added some international pressure for its protection. But, in general, the many scientific discoveries regarding the Amazon have not been helpful in improving its conservation. Instead, a combination of new agricultural technologies, anthropocentric philosophies, and economic changes has strongly promoted forest clearing.
From the 1980s to the present day, Amazon conservation efforts have increasingly diversified, and now consist of five theoretically complementary strategies: (1) the creation of more, larger and better managed protected areas, including biological corridors; (2) the protection of more and larger indigenous territories; (3) the promotion of a series of “sustainable use” options such as “community based conservation,” sustainable forestry, and agroforestry; (4) the financing of conservation through debt swaps and related financial mechanisms for mitigating climate change and; (5) the use of better legislation, monitoring, and control. Five small protected areas have existed in the Amazon since the early 1960s but, in response to the road building boom of the 1970s, several larger patches of forests were set aside with the aim of conserving viable samples of biological diversity. Today, around 25 % of the Amazon is designated as protected areas, but almost half of these areas are categorized in a way that allows human presence and resource exploitation, and there is no effective management. Another 25.3% is designated to indigenous people who may or not conserve the forest. Excluding areas of overlap, both types of protected areas cover 41.2% of the Amazon. Neither strategy has fully achieved its objective, alone or together, and development pressures and threats grow as road construction and deforestation continue relentlessly with increasing funding by multilateral and national banks and pressure from transnational enterprises.
The future will be directed by unprecedented agricultural expansion and the corresponding intensification of deforestation and forest degradation. Additionally, the Amazon basin will be impacted by new, larger hydraulic works. Mining will increase and spread. Policy makers of Amazon countries still view the region as the future for expanding conventional development, and the population continues to be indifferent.
Russian environmental history is a new field of inquiry, with the first archivally based monographs appearing only in the last years of the 20th century. Despite the field’s youth, scholars studying the topic have developed two distinct and contrasting approaches to its central question: How should the relationship between Russian culture and the natural world be characterized? Implicit in this question are two others: Is the Russian attitude toward the non-human world more sensitive than that which prevails in the West; and if so, is the Russian environment healthier or more stable than that of the United States and Western Europe? In other words, does Russia, because of its traditional suspicion of individualism and consumerism, have something to teach the West? Or, on the contrary, has the Russian historical tendency toward authoritarianism and collectivism facilitated predatory policies that have degraded the environment? Because environmentalism as a political movement and environmental history as an academic subject both emerged during the Cold War, at a time when the Western social, political, and economic system vied with the Soviet approach for support around the world, the comparative (and competitive) aspect of Russian environmental history has always been an important factor, although sometimes an implicit one. Accordingly, the existing scholarly works about Russian environmental history generally fall into one of two camps: one very critical of the Russian environmental record and the seeming disregard of the Russian government for environmental damage, and a somewhat newer group of works that draw attention to the fundamentally different concerns that motivate Russian environmental policies. The first group emphasizes Russian environmental catastrophes such as the desiccated Aral Sea, the eroded Virgin Lands, and the public health epidemics related to the severely polluted air of Soviet industrial cities. The environmental crises that the first group cites are, most often, problems once prevalent in the West, but successfully ameliorated by the environmental legislation of the late 1960s and early 1970s. The second group, in contrast, highlights Russian environmental policies that do not have strict Western analogues, suggesting that a thorough comparison of the Russian and Western environmental records requires, first of all, a careful examination of what constitutes environmental responsibility.
David E. Clay, Sharon A. Clay, Thomas DeSutter, and Cheryl Reese
Since the discovery that food security could be improved by pushing seeds into the soil and later harvesting a desirable crop, agriculture and agronomy have gone through cycles of discovery, implementation, and innovation. Discoveries have produced predicted and unpredicted impacts on the production and consumption of locally produced foods. Changes in technology, such as the development of the self-cleaning steel plow in the 18th century, provided a critical tool needed to cultivate and seed annual crops in the Great Plains of North America. However, plowing the Great Plains would not have been possible without the domestication of plants and animals and the discovery of the yoke and harness. Associated with plowing the prairies were extensive soil nutrient mining, a rapid loss of soil carbon, and increased wind and water erosion. More recently, the development of genetically modified organisms (GMOs) and no-tillage planters has contributed to increased adoption of conservation tillage, which is less damaging to the soil. In the future, the ultimate impact of climate change on agronomic practices in the North American Great Plains is unknown. However, projected increasing temperatures and decreased rainfall in the southern Great Plains (SGP) will likely reduce agricultural productivity. Different results are likely in the northern Great Plains (NGP) where higher temperatures can lead to increased agricultural intensification, the conversion of grassland to cropland, increased wildlife fragmentation, and increased soil erosion. Precision farming, conservation, cover crops, and the creation of plants better designed to their local environment can help mitigate these effects. However, changing practices require that farmers and their advisers understand the limitations of the soils, plants, and environment, and their production systems. Failure to implement appropriate management practices can result in a rapid decline in soil productivity, diminished water quality, and reduced wildlife habitat.
Simon Holdaway and Rebecca Phillipps
Northeast Africa forms an interesting case study for investigating the relationship between changes in environment and agriculture. Major climatic changes in the early Holocene led to dramatic changes in the environment of the eastern Sahara and to the habitation of previously uninhabitable regions. Research programs in the eastern Sahara have uncovered a wealth of archaeological evidence for sustained occupation during the African Humid Period, from about 11,000 years ago. Initial studies of faunal remains seemed to indicate early shifts in economic practice toward cattle pastoralism. Although this interpretation was much debated when it was first proposed, the possibility of early pastoralism stimulated discussion concerning the relationships between people and animals in particular environmental contexts, and ultimately led to questions concerning the role of agriculture imported from elsewhere in contrast to local developments. Did agriculture, or indeed cultivation and domestication more generally (sensu Fuller & Hildebrand, 2013), develop in North Africa, or were the concepts and species imported from Southwest Asia? And if agriculture did spread from elsewhere, were just the plants and animals involved, or was the shift part of a full socioeconomic suite that included new subsistence strategies, settlement patterns, technologies, and an agricultural “culture”? And finally, was this shift, wherever and however it originated, related to changes in the environment during the early to mid-Holocene?
These questions refer to the “big ideas” that archaeologists explore, but before answers can be formed it is important to consider the nature of the material evidence on which they are based. Archaeologists must consider not only what they discover but also what might be missing. Materials from the past are preserved only in certain places, and of course some materials can be preserved better than others. In addition, people left behind the material remains of their activities, but in doing so they did not intend these remains to be an accurate historical record of their actions. Archaeologists need to consider how the remains found in one place may inform us about a range of activities that occurred elsewhere for which the evidence may be less abundant or missing. This is particularly true for Northeast Africa where environmental shifts and consequent changes in resource abundance often resulted in considerable mobility. This article considers the origins of agriculture in the region covering modern-day Egypt and Sudan, paying particular attention to the nature of the evidence from which inferences about past socioeconomies may be drawn.
Noa Kekuewa Lincoln and Peter Vitousek
Agriculture in Hawaiʻi was developed in response to the high spatial heterogeneity of climate and landscape of the archipelago, resulting in a broad range of agricultural strategies. Over time, highly intensive irrigated and rainfed systems emerged, supplemented by extensive use of more marginal lands that supported considerable populations. Due to the late colonization of the islands, the pathways of development are fairly well reconstructed in Hawaiʻi. The earliest agricultural developments took advantage of highly fertile areas with abundant freshwater, utilizing relatively simple techniques such as gardening and shifting cultivation. Over time, investments into land-based infrastructure led to the emergence of irrigated pondfield agriculture found elsewhere in Polynesia. This agricultural form was confined by climatic and geomorphological parameters, and typically occurred in wetter, older landscapes that had developed deep river valleys and alluvial plains. Once initiated, these wetland systems saw regular, continuous development and redevelopment. As populations expanded into areas unable to support irrigated agriculture, highly diverse rainfed agricultural systems emerged that were adapted to local environmental and climatic variables. Development of simple infrastructure over vast areas created intensive rainfed agricultural systems that were unique in Polynesia. Intensification of rainfed agriculture was confined to areas of naturally occurring soil fertility that typically occurred in drier and younger landscapes in the southern end of the archipelago. Both irrigated and rainfed agricultural areas applied supplementary agricultural strategies in surrounding areas such as agroforestry, home gardens, and built soils. Differences in yield, labor, surplus, and resilience of agricultural forms helped shape differentiated political economies, hierarchies, and motivations that played a key role in the development of sociopolitical complexity in the islands.
Nations rapidly industrialized after World War II, sharply increasing the extraction of resources from the natural world. Colonial empires broke up on land after the war, but they were re-created in the oceans. The United States, Japan, and the Soviet Union, as well as the British, Germans, and Spanish, industrialized their fisheries, replacing fleets of small-scale, independent artisanal fishermen with fewer but much larger government-subsidized ships. Nations like South Korea and China, as well as the Eastern Bloc countries of Poland and Bulgaria, also began fishing on an almost unimaginable scale. Countries raced to find new stocks of fish to exploit. As the Cold War deepened, nations sought to negotiate fishery agreements with Third World nations. The conflict over territorial claims led to the development of the Law of the Sea process, starting in 1958, and to the adoption of 200-mile exclusive economic zones (EEZ) in the 1970s.
Fishing expanded with the understanding that fish stocks were robust and could withstand high harvest rates. The adoption of maximum sustained yield (MSY) after 1954 as the goal of postwar fishery negotiations assumed that fish had surplus and that scientists could determine how many fish could safely be caught. As fish stocks faltered under the onslaught of industrial fisheries, scientists re-assessed their assumptions about how many fish could be caught, but MSY, although modified, continues to be at the heart of modern fisheries management.
This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Environmental Science. Please check back later for the full article.
The Quaternary period of Earth history, which commenced ca. 2.6 Ma ago, is noted for a series of dramatic shifts in global climate between long, cool (“icehouse”) and short, temperate (“greenhouse”) stages. This also coincides with the extinction of later Australopithecine hominins and evolution of modern Homo sapiens.
Wide recognition of a fourth, Quaternary, order of geologic time emerged in Europe between ca. 1760–1830 and became closely identified with the concept of an ice age. This most recent episode in Earth history is also the best preserved in stratigraphic and landscape records. Indeed, much of its character and processes continue in present time, which prompted early geologists’ recognition of the concept of uniformitarianism—the present is the key to the past.
Quaternary time was quickly divided into a dominant Pleistocene (“most recent”) epoch, characterized by cyclical growth and decay of major continental ice sheets and peripheral permafrost. Disappearance of most of these ice sheets, except in Antarctica and Greenland today, ushered in the Holocene (“wholly modern”) epoch, once thought to terminate the Ice Age but now seen as the current interglacial or temperate stage, commencing ca. 11.7 ka ago. Covering 30–50% of Earth’s land surface at their maxima, ice sheets and permafrost squeezed remaining biomes into a narrower circum-equatorial zone, where research indicated the former occurrence of pluvial and desiccation events. Early efforts to correlate them with mid-high latitude glacials and interglacials revealed the complex and often asynchronous Pleistocene record.
Nineteenth-century recognition of just four glaciations reflected a reliance on geomorphology and short terrestrial stratigraphic records, concentrated in northern hemisphere mid- and high-latitudes, until the 1970s. Correlation of δ16-18 O isotope signals from seafloor sediments (from ocean drilling programs after the 1960s) with polar ice core signals from the 1980s onward has revolutionized our understanding of the Quaternary, facilitating a sophisticated, time-constrained record of events and environmental reconstructions from regional to global scales. Records from oceans and ice sheets, some spanning 105–106 years, are augmented by similar long records from loess, lake sediments, and speleothems (cave sediments). Their collective value is enhanced by innovative analytical and dating tools.
Over 100 Marine Isotope Stages (MIS) are now recognized in the Quaternary, with dramatic climate shifts at decadal and centennial timescales—with the magnitude of 22 MIS in the past 900,000 years considered to reflect significant ice sheet accumulation and decay. Each cycle between temperate and cool conditions (odd- and even-numbered MIS respectively) is time-asymmetric, with progressive cooling over 80,000 to 100,000 years, followed by an abrupt termination then rapid return to temperate conditions for a few thousand years.
The search for causes of Quaternary climate and environmental change embraces all strands of Earth System Science. Strong correlation between orbital forcing and major climate changes (summarized as the Milankovitch mechanism) is displacing earlier emphasis on radiative (direct solar) forcing, but uncertainty remains over how the orbital signal is amplified or modulated. Tectonic forcing (ocean-continent distributions, tectonic uplift, and volcanic outgassing), atmosphere-biogeochemical and greenhouse gas exchange, ocean-land surface albedo and deep- and surface-ocean circulation are all contenders and important agents in their own right.
Modern understanding of Quaternary environments and processes feeds an exponential growth of multidisciplinary research, numerical modeling, and applications. Climate modeling exploits mutual benefits to science and society of “hindcasting,” using paleoclimate data to aid understanding of the past and increasing confidence in modeling forecasts. Pursuit of more detailed and sophisticated understanding of ocean-atmosphere-cryosphere-biosphere interaction proceeds apace.
The Quaternary is also the stage on which human evolution plays. And the essential distinction between natural climate variability and human forcing is now recognized as designating, in present time, a potential new Anthropocene epoch. Quaternary past and present are major keys to its future.