Science Current Events | Science News | Brightsurf.com
 

Agricultural methods of early civilizations may have altered global climate, study suggests

August 17, 2009

Massive burning of forests for agriculture thousands of years ago may have increased atmospheric carbon dioxide enough to alter global climate and usher in a warming trend that continues today, according to a new study that appears online Aug. 17 in the journal Quaternary Science Reviews.

Researchers at the University of Virginia and the University of Maryland-Baltimore County say that today's 6 billion people use about 90 percent less land per person for growing food than was used by far smaller populations early in the development of civilization. Those early societies likely relied on slash-and-burn techniques to clear large tracts of land for relatively small levels of food production.

"They used more land for farming because they had little incentive to maximize yield from less land, and because there was plenty of forest to burn," said William Ruddiman, the lead author and a professor emeritus of environmental sciences at the University of Virginia. "They may have inadvertently altered the climate."

Ruddiman is a climate scientist who specializes in investigating ocean-sediment and ice-core records. In recent years he has searched across scientific disciplines - anthropology, archaeology, population dynamics, climatology - to gain insight into how humans may have affected climate over the millennia.

He said that early populations likely used a land-clearing method that involved burning forests, then planting crop seed among the dead stumps in the enriched soil. They would use a large plot until the yield began to decline, and then would burn off another area of forest for planting.

They would continue this form of rotation farming, ever expanding the cleared areas as their populations grew. They possibly cleared five or more times more land than they actually farmed at any given time. It was only as populations grew much larger, and less land was available for farming or for laying fallow, that societies adopted more intensive farming techniques and slowly gained more food yield from less land.

Ruddiman notes that with the highly efficient and intensive farming of today, growing populations are using less land per capita for agriculture. Forests are returning in many parts of the world, including the northeastern United States, Europe, Canada, Russia and even parts of China.

The positive environmental effects of this reforestation, however, are being canceled out by the large-scale burning of fossil fuels since the advent of the Industrial Revolution, which began about 150 years ago. Humans continue to add excessive levels of carbon dioxide to the atmosphere, contributing to a global warming trend, Ruddiman said.

Five years ago, Ruddiman made headlines with a hypothesis that humans began altering global climate thousands of years ago, not just since the Industrial Revolution. That theory has since been criticized by some climate scientists who believe that early populations were too small to create enough carbon dioxide to alter climate.

According to projections from some models of past land use, large-scale land clearing and resulting carbon emissions have only occurred during the industrial era, as a result of huge increases in population.

But Ruddiman, and his co-author Erle Ellis, an ecologist at UMBC who specializes in land-use change, say these models are not accounting for the possibly large effects on climate likely caused by early farming methods.

"Many climate models assume that land use in the past was similar to land use today; and that the great population explosion of the past 150 years has increased land use proportionally," Ellis said. "We are proposing that much smaller earlier populations used much more land per person, and may have more greatly affected climate than current models reflect."

Ruddiman and Ellis based their finding on several studies by anthropologists, archaeologists and paleoecologists indicating that early civilizations used a great amount of land to grow relatively small amounts of food. The researchers compared what they found with the way most land-use models are designed, and found a disconnect between modeling and field-based studies.

"It was only as our populations grew larger over thousands of years, and needed more food, that we improved farming technologies enough to begin using less land for more yield," Ruddiman said. "We suggest in this paper that climate modelers might consider how land use has changed over time, and how this may have affected the climate."

University of Virginia


Related Global Climate Current Events and Global Climate News Articles


Hydrothermal vents, methane seeps play enormous role in marine life, global climate
The hydrothermal vents and methane seeps on the ocean floor that were once thought to be geologic and biological oddities are now emerging as a major force in ocean ecosystems, marine life and global climate.

Organism responsible for paralytic shellfish poisoning may affect fisheries
The toxic dinoflagellate, Alexandrium fundyense, is a photosynthetic plankton--a microscopic organism floating in the ocean, unable to swim against a current.

Deep, old water explains why Antarctic Ocean hasn't warmed
The waters surrounding Antarctica may be one of the last places to experience human-driven climate change.

Spring snow a no-go?
Spring snowpack, relied on by ski resorts and water managers throughout the Western United States, may be more vulnerable to a warming climate in coming decades, according to a new University of Utah study.

A planet 1,200 light-years away is a good prospect for a habitable world
A distant planet known as Kepler-62f could be habitable, a team of astronomers reports.

Current atmospheric models underestimate the dirtiness of Arctic air
Black carbon aerosols--particles of carbon that rise into the atmosphere when biomass, agricultural waste, and fossil fuels are burned in an incomplete way--are important for understanding climate change, as they absorb sunlight, leading to higher atmospheric temperatures, and can also coat Arctic snow with a darker layer, reducing its reflectivity and leading to increased melting.

New research confirms continued, unabated and large-scale amphibian declines
New U.S. Geological Survey-led research suggests that even though amphibians are severely declining worldwide, there is no smoking gun - and thus no simple solution - to halting or reversing these declines.

Atmospheric aerosols can significantly cool down climate
It is possible to significantly slow down and even temporarily stop the progression of global warming by increasing the atmospheric aerosol concentration, shows a new study from the University of Eastern Finland. However, climate engineering does not remove the need to reduce greenhouse gas emissions.

New Berkeley Lab study tallies environmental and public health benefits of solar power
Solar power could deliver $400 billion in environmental and public health benefits throughout the United States by 2050, according to a study from the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) and National Renewable Energy Laboratory (NREL).

Polluted dust can impact ocean life thousands of miles away, study says
As climatologists closely monitor the impact of human activity on the world's oceans, researchers at the Georgia Institute of Technology have found yet another worrying trend impacting the health of the Pacific Ocean.
More Global Climate Current Events and Global Climate News Articles

Global Climate Change: Turning Knowledge Into Action

Global Climate Change: Turning Knowledge Into Action
by David E. Kitchen (Author)


The science of climate change is a complex subject that balances the physical record and scientific fact with politics, policy, and ethics - and is of particular importance to the geosciences. This thoughtfully crafted new text and accompanying media encourage non-science majors to practice critical thinking, analysis, and discourse about climate change themes. Taking a cross-disciplinary approach, acclaimed educator and researcher, David Kitchen, examines not only the physical science, but the social, economic, political, energy, and environmental issues surrounding climate change. His goal: to turn knowledge into action, equipping students with the knowledge and critical skills to make informed decisions, separate facts from fiction, and participate in the public debate.

Global Climate Change

Global Climate Change
by Arnold J. Bloom (Author)


Mark Twain s comment everybody talks about the weather, but nobody does anything about it no longer applies: human activities have altered the global climate, and governments are implementing policies to avoid more extreme perturbations. Global Climate Change examines the factors responsible for global climate change and the geophysical, biological, economic, legal, and cultural consequences of such changes. The book highlights the complexity of decision-making under uncertainty, contrasting the methods that various disciplines employ to evaluate past and future conditions.

Global Climate Change and Human Health: From Science to Practice

Global Climate Change and Human Health: From Science to Practice
by George Luber (Editor), Jay Lemery (Editor)


Learn the foundations of climate science and human health Global Climate Change and Human Health examines the environmental crisis from a public health and clinical health perspective, giving students and clinicians the information they need to prepare for the future of health care. Edited by George Luber, associate director for climate change at the Centers for Disease Control and Prevention, and Jay Lemery, associate professor at the University of Colorado School of Medicine and section chief of Wilderness and Environmental Medicine in the Department of Emergency Medicine, and including chapters written by luminaries in the field, this landmark book provides a comprehensive introduction to climate change and health. Students will learn about climate changes direct effect on health,...

Climate Change: What Everyone Needs to Know®

Climate Change: What Everyone Needs to Know®
by Joseph Romm (Author)


Climate change will have a bigger impact on humanity than the Internet has had. The last decade's spate of superstorms, wildfires, heat waves, and droughts has accelerated the public discourse on this topic and lent credence to climatologist Lonnie Thomson's 2010 statement that climate change "represents a clear and present danger to civilization." In June 2015, the Pope declared that action on climate change is a moral issue.

This book offers the most up-to-date examination of climate change's foundational science, its implications for our future, and the core clean energy solutions. Alongside detailed but highly accessible descriptions of what is causing climate change, this entry in the What Everyone Needs to Know series answers questions about the practical implications of this...

Global Weirdness: Severe Storms, Deadly Heat Waves, Relentless Drought, Rising Seas, and the Weather of the Future

Global Weirdness: Severe Storms, Deadly Heat Waves, Relentless Drought, Rising Seas, and the Weather of the Future
by Climate Central (Author)


Global Weirdness summarizes everything we know about the science of climate change, explains what is likely to happen to the climate in the future, and lays out, in practical terms, what we can do to avoid further shifts. In fifty easy-to-read entries, Climate Central tackles basic questions such as:
-Is climate ever “normal”?
-Why and how do fossil-fuel burning and other human practices produce greenhouse gases?
-What natural forces have caused climate change in the past?
-What risks does climate change pose for human health?
-What accounts for the diminishment of mountain glaciers and small ice caps around the world since 1850?
-What are the economic costs and benefits of reducing carbon emissions?

Illustrated throughout with clarifying graphics,...

Global Climate Change: A Primer

Global Climate Change: A Primer
by Orrin H. Pilkey Jr. (Author), Keith C. Pilkey (Author)


An internationally recognized expert on the geology of barrier islands, Orrin H. Pilkey is one of the rare academics who engages in public advocacy about science-related issues. He has written dozens of books and articles explaining coastal processes to lay readers, and he is a frequent and outspoken interviewee in the mainstream media. Here, the colorful scientist takes on climate change deniers in an outstanding and much-needed primer on the science of global change and its effects.After explaining the greenhouse effect, Pilkey, writing with son Keith, turns to the damage it is causing: sea level rise, ocean acidification, glacier and sea ice melting, changing habitats, desertification, and the threats to animals, humans, coral reefs, marshes, and mangroves. These explanations are...

The Climate Casino: Risk, Uncertainty, and Economics for a Warming World

The Climate Casino: Risk, Uncertainty, and Economics for a Warming World
by William D. Nordhaus (Author)


The world’s leading economic thinker on climate change analyzes the economics and politics of the central environmental issue of today and points the way to real solutions

Climate change is profoundly altering our world in ways that pose major risks to human societies and natural systems. We have entered the Climate Casino and are rolling the global-warming dice, warns economist William Nordhaus. But there is still time to turn around and walk back out of the casino, and in this essential book the author explains how. Bringing together all the important issues surrounding the climate debate, Nordhaus describes the science, economics, and politics involved—and the steps necessary to reduce the perils of global warming. Using language accessible to any concerned citizen and...

Climate Change Reality Check: Basic Facts that Quickly Prove the Climate Change Crusade is Wrong and Dangerous

Climate Change Reality Check: Basic Facts that Quickly Prove the Climate Change Crusade is Wrong and Dangerous
by Calvin Fray (Author)


In all of the debate and discussion about climate change, why hasn’t anyone explained the science in plain and simple terms clear enough to understand--once and for all?
“Great [analysis]. Just the right amount of science. Common sense and rational.” -- Wayne R.
The greenhouse effect is always quoted—but that is a METAPHOR. What is the fundamental physical process that drives it?
And how exactly does human activity play such a powerful role with it?
How did we go from worrying about global warming to climate change…to carbon dioxide (CO2) emissions?
“Wonderful book! Best I’ve ever read on any debate. Real science that can be replicated = reality.” – Scott D.
Are there gases more powerful and influential in the greenhouse effect than CO2?...

Global Crisis: War, Climate Change and Catastrophe in the Seventeenth Century

Global Crisis: War, Climate Change and Catastrophe in the Seventeenth Century
by Geoffrey Parker (Author)


Geoffrey Parker presents the firsthand testimony of men and women who saw and suffered from the sequence of political, economic, and social crises between 1618 to the late 1680s. He also deploys the scientific evidence of climate change during this period.

Global Climate Change Impacts in the United States

Global Climate Change Impacts in the United States
by Thomas R. Karl (Editor), Jerry M. Melillo (Editor), Thomas C. Peterson (Editor), Susan J. Hassol (Editor)


This book is the most comprehensive report to date on the wide range of impacts of climate change in the United States. It is written in plain language to better inform members of the public and policymakers. The report finds that global warming is unequivocal, primarily human-induced, and its impacts are already apparent in transportation, agriculture, health, and water and energy supplies. These impacts are expected to grow with continued climate change - the higher the levels of greenhouse gas emissions, the greater the impacts. The report illustrates how these impacts can be kept to a minimum if greenhouse gas emissions are reduced. The choices we make now will determine the severity of climate change impacts in the future. This book will help citizens, business leaders, and...

© 2016 BrightSurf.com