Plows, Plagues and Petroleum

Last updated July 20, 2024

Plows, Plagues and Petroleum: How Humans Took Control of Climate is a 2005 book^[1] published by Princeton University Press and written by William Ruddiman, a paleoclimatologist and Professor Emeritus at the University of Virginia. He has authored and co-authored several books^[2] and academic papers^[3] on the subject of climate change. Scientists often refer to this period as the "Anthropocene" and define it as the era in which humans first began to alter the Earth's climate and ecosystems. Ruddiman contends that human induced climate change began as a result of the advent of agriculture thousands of years ago and resulted in warmer temperatures that could have possibly averted another ice age; this is the early anthropocene hypothesis.

Synopsis

Ruddiman begins the book with a brief introduction to the science of climate change and the various individuals who have been key in influencing the field over the years. He also notes that the Earth's climate has been drifting toward cooler temperatures for the last 55 million years. The dominant hypothesis for this trend is that large volcanic eruptions have subsided while increasing amounts of carbon dioxide have been absorbed out of the atmosphere due to interactions between monsoon rains and ground-up rock exposed by India pushing into Asia and creating the Himalayas. Additionally, it is believed that the melting ice that produced higher sea levels resulted in the ocean absorbing more carbon dioxide out of the atmosphere. These two natural occurrences resulted in less carbon dioxide in the atmosphere hence possibly producing the general cooling trend.

According to Ruddiman, beginning about 900,000 years ago the Earth has begun to go through regular glacial cycles in which glaciers or ice have covered approximately one-quarter of the Earth's total surface. These conditions typically last for about 100,000 years and are followed by brief interglacial periods of more temperate weather. Ruddiman cites various researchers in geology and astronomy who pioneered the understanding of Earth's climate as a function of its orbit. The various cycles of Earth's climate seem to be explained by the eccentricity, axial tilt, and precession of the Earth's orbit as well as cycles in the amount of solar radiation. Ruddiman primarily relies on the groundwork by Milutin Milankovitch to explain the effects of solar radiation and Earth's orbit on the climate. By examining ice cores from around the world scientists have been able to link levels of greenhouse gases such as carbon dioxide and methane to the various cycles of Earth's climate history. The discovery of carbon dating aided a great deal in developing this understanding. Upon investigating the levels of carbon dioxide and methane in the Earth's atmosphere in the most recent interglacial period—10,000 years ago—Ruddiman noticed that levels of carbon dioxide and methane were steadily rising despite the fact that the Earth's natural cycles determined that they should have been decreasing. It was this discovery that led to Ruddiman's search for an explanation and ultimately the creation of this book.

Ruddiman's central argument is that this most recent interglacial period has deviated from the natural cycle because of human activities, most importantly farming. Approximately 10,000 years ago the ice that once covered large portions of the northern hemisphere began to recede and gave rise to a new way of life for early humans. In the beginning, these early humans had little impact on the environment because they were primarily hunter-gatherer societies that moved from location to location allowing previously inhabited locations to be reclaimed by nature. However, about 8,000 years ago humans first developed agriculture and a domesticated lifestyle that allowed them to continually inhabit regions and build large civilizations. Ruddiman claims that carbon dioxide emission records indicate that levels in the atmosphere began to rise at about this same time. This process was intensified as the centuries passed and new technologies such as animal husbandry and the plow made their way into more and more cultures. These new technologies allowed for more efficient methods of clearing forests and making room for increasing populations. According to previous interglacial periods, the concentration of carbon dioxide should have fallen by about 20 parts per million instead of rising by 20 parts per million. Ruddiman uses estimates of population, the forest cleared per person and carbon emitted per square kilometer cleared to approximate the total impact and concludes that the magnitude is reasonably close to the extra carbon dioxide accumulated during the period.

Ruddiman also attributes the rise of methane gas in the atmosphere to human-related activities. The most notable of these activities is the cultivation of rice in artificial wetlands in Asia and increased animal waste due to increasing populations of domesticated animals. According to Ruddiman methane concentrations should have peaked about 11,000 years ago slightly above 700 parts per billion and then declined to about 450 parts per billion today. Methane levels followed this cycle at first, but about 5000 years ago they began to rebound and currently the concentration is about 275 parts per billion above the previous trends.

According to Ruddiman farming and related activities resulted in large amounts of greenhouse gases (carbon dioxide and methane) being released into the atmosphere at a time when natural cycles of the Earth indicated they should have been falling. The result has been an unintended warming cycle that prevented the Earth from entering into another ice age.^[4] Ruddiman goes as far as to say that if these gases had not been released into the atmosphere, areas in northern Canada such as Hudson Bay and Baffin Island would currently be covered in ice today.

Throughout the record of carbon dioxide and methane emissions, there are drops and rises in the amount of concentrations present in the atmosphere. Ruddiman explains these "wiggles" by claiming that they appear at times of major outbreaks of disease such as the bubonic plague in the 1,300's and the prevalence of old world diseases in the Americas after the arrival of Columbus. Both of these events resulted in large numbers of people dying and the land they once inhabited being reclaimed by the forest. This resulted in increased amounts of carbon dioxide being taken out of the atmosphere, hence causing global temperatures to cool down. Ruddiman claims that the Little Ice Age, starting in the 13th century and ending sometime in the early 19th century was caused by the decreased population and the re-forestation of previously cleared lands as a result of the diseases that killed off so many people.

The last aspect of Ruddiman's discussion of climate change relates to the future of petroleum use on Earth. It is commonly known that the world's supply of fossil fuels is rapidly depleting and even conservative estimates claim that the supply will not last much more than 150-200 more years. Ruddiman claims that when this source of natural fuels has been depleted, humankind will have to resort to using the large quantities of coal that still exist all over the planet. This, according to Ruddiman, will result in a continued warming trend that will only stop when technology either produces a new source of fuel or figures out a way to separate the carbon dioxide emissions prior to being released into the atmosphere. Ruddiman is quite skeptical of both scenarios in the near future because of the increased costs and technological advancements that would have to be made in such a short time. Eventually, carbon and methane emissions will be controlled and lowered a great deal and Ruddiman asserts when this happens the Earth will most likely begin an era of cooling temperatures.

Critical assessment

Gavin Schmidt, a climate scientist at the NASA Goddard Institute for Space Studies in New York, described Ruddiman's ideas as intriguing, but the conclusions largely depended on a comparison of methane changes in the current warm period with those in the Vostok ice core which correlated with orbital changes, and more recent research indicated that these might not be applicable to present changes. The newer EPICA core showed only a small increase in methane during the last 5,000 years, which was generally attributed to the development of the boreal wetlands and major river deltas after the ice from the previous ice age melted and caused the sea level to rise to its current location. It was very uncertain that the relatively small human populations and cultivated areas could have made a significant difference. More research was needed to quantify relevant factors.^[5]

Notes

↑ Berger, Wolfgang (March–April 2006). "Review: Plows, Plagues, and Petroleum by William F. Ruddiman". American Scientist.
↑ "de beste bron van informatie over gsajournals. Deze website is te koop!". GSA Today. 12. gsajournals.org: 23. 2002. doi:10.1130/1052-5173(2002)012<0023:ESCPAF>2.0.CO;2. ISSN 1052-5173 . Retrieved 2012-03-17.
↑ Ruddiman, William F (2003). "The Anthropogenic Greenhouse Era Began Thousands of Years Ago" (PDF). Climate Change. Retrieved 2022-04-24.
↑ Ruddiman, William F (2005). "A test of the overdue-glaciation hypothesis" (PDF). Quaternary Science Reviews. Archived from the original (PDF) on 2006-10-03. Retrieved 2006-10-03.
↑ Schmidt, Gavin (September 2004). "NASA GISS: Research Features: Methane: A Scientific Journey from Obscurity to Climate Super-Stardom". Giss.nasa.gov. Archived from the original on 2004-09-10.

Related Research Articles

The scientific community has been investigating the causes of climate change for decades. After thousands of studies, it came to a consensus, where it is "unequivocal that human influence has warmed the atmosphere, ocean and land since pre-industrial times." This consensus is supported by around 200 scientific organizations worldwide, The dominant role in this climate change has been played by the direct emissions of carbon dioxide from the burning of fossil fuels. Indirect CO₂ emissions from land use change, and the emissions of methane, nitrous oxide and other greenhouse gases play major supporting roles.

<span class="mw-page-title-main">Global warming potential</span> Potential heat absorbed by a greenhouse gas

Global warming potential (GWP) is an index to measure how much infrared thermal radiation a greenhouse gas would absorb over a given time frame after it has been added to the atmosphere. The GWP makes different greenhouse gases comparable with regard to their "effectiveness in causing radiative forcing". It is expressed as a multiple of the radiation that would be absorbed by the same mass of added carbon dioxide, which is taken as a reference gas. Therefore, the GWP has a value of 1 for CO₂. For other gases it depends on how strongly the gas absorbs infrared thermal radiation, how quickly the gas leaves the atmosphere, and the time frame being considered.

<span class="mw-page-title-main">Ice age</span> Period of long-term reduction in temperature of Earths surface and atmosphere

An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages, and greenhouse periods during which there are no glaciers on the planet. Earth is currently in the ice age called Quaternary glaciation. Individual pulses of cold climate within an ice age are termed glacial periods, and intermittent warm periods within an ice age are called interglacials or interstadials.

Climate variability includes all the variations in the climate that last longer than individual weather events, whereas the term climate change only refers to those variations that persist for a longer period of time, typically decades or more. Climate change may refer to any time in Earth's history, but the term is now commonly used to describe contemporary climate change, often popularly referred to as global warming. Since the Industrial Revolution, the climate has increasingly been affected by human activities.

Global cooling was a conjecture, especially during the 1970s, of imminent cooling of the Earth culminating in a period of extensive glaciation, due to the cooling effects of aerosols or orbital forcing. Some press reports in the 1970s speculated about continued cooling; these did not accurately reflect the scientific literature of the time, which was generally more concerned with warming from an enhanced greenhouse effect.

This glossary of climate change is a list of definitions of terms and concepts relevant to climate change, global warming, and related topics.

The geologic temperature record are changes in Earth's environment as determined from geologic evidence on multi-million to billion (10⁹) year time scales. The study of past temperatures provides an important paleoenvironmental insight because it is a component of the climate and oceanography of the time.

<span class="mw-page-title-main">Climate system</span> Interactions that create Earths climate and may result in climate change

Earth's climate system is a complex system with five interacting components: the atmosphere (air), the hydrosphere (water), the cryosphere, the lithosphere and the biosphere. Climate is the statistical characterization of the climate system. It represents the average weather, typically over a period of 30 years, and is determined by a combination of processes, such as ocean currents and wind patterns. Circulation in the atmosphere and oceans transports heat from the tropical regions to regions that receive less energy from the Sun. Solar radiation is the main driving force for this circulation. The water cycle also moves energy throughout the climate system. In addition, certain chemical elements are constantly moving between the components of the climate system. Two examples for these biochemical cycles are the carbon and nitrogen cycles.

William F. Ruddiman is a palaeoclimatologist and Professor Emeritus at the University of Virginia. Ruddiman earned an undergraduate degree in geology in 1964 at Williams College, and a Ph.D. in marine geology from Columbia University in 1969. Ruddiman worked at the US Naval Oceanographic Office from 1969 to 1976, and at Columbia's Lamont–Doherty Earth Observatory from 1976 to 1991. He moved to Virginia in 1991, serving as a professor in Environmental Sciences. Ruddiman's research interests center on climate change over several time scales. He is a Fellow of both the Geological Society of America and the American Geophysical Union. Ruddiman has participated in 15 oceanographic cruises, and was co-chief of two deep-sea drilling cruises.

Greenhouse gas (GHG) emissions from human activities intensify the greenhouse effect. This contributes to climate change. Carbon dioxide, from burning fossil fuels such as coal, oil, and natural gas, is one of the most important factors in causing climate change. The largest emitters are China followed by the United States. The United States has higher emissions per capita. The main producers fueling the emissions globally are large oil and gas companies. Emissions from human activities have increased atmospheric carbon dioxide by about 50% over pre-industrial levels. The growing levels of emissions have varied, but have been consistent among all greenhouse gases. Emissions in the 2010s averaged 56 billion tons a year, higher than any decade before. Total cumulative emissions from 1870 to 2022 were 703 GtC, of which 484±20 GtC from fossil fuels and industry, and 219±60 GtC from land use change. Land-use change, such as deforestation, caused about 31% of cumulative emissions over 1870–2022, coal 32%, oil 24%, and gas 10%.

In Earth's atmosphere, carbon dioxide is a trace gas that plays an integral part in the greenhouse effect, carbon cycle, photosynthesis and oceanic carbon cycle. It is one of several greenhouse gases in the atmosphere of Earth. The current global average concentration of carbon dioxide (CO₂) in the atmosphere is 421 ppm (0.04%) as of May 2022. This is an increase of 50% since the start of the Industrial Revolution, up from 280 ppm during the 10,000 years prior to the mid-18th century. The increase is due to human activity.

Throughout Earth's climate history (Paleoclimate) its climate has fluctuated between two primary states: greenhouse and icehouse Earth. Both climate states last for millions of years and should not be confused with glacial and interglacial periods, which occur as alternate phases within an icehouse period and tend to last less than 1 million years. There are five known Icehouse periods in Earth's climate history, which are known as the Huronian, Cryogenian, Andean-Saharan, Late Paleozoic, and Late Cenozoic glaciations. The main factors involved in changes of the paleoclimate are believed to be the concentration of atmospheric carbon dioxide, changes in Earth's orbit, long-term changes in the solar constant, and oceanic and orogenic changes from tectonic plate dynamics. Greenhouse and icehouse periods have played key roles in the evolution of life on Earth by directly and indirectly forcing biotic adaptation and turnover at various spatial scales across time.

This is a list of climate change topics.

<span class="mw-page-title-main">Methane</span> Hydrocarbon compound (CH₄) in natural gas

Methane is a chemical compound with the chemical formula CH₄. It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The abundance of methane on Earth makes it an economically attractive fuel, although capturing and storing it is hard because it is a gas at standard temperature and pressure.

<span class="mw-page-title-main">Greenhouse gas</span> Gas in an atmosphere that absorbs and emits radiation at thermal infrared wavelengths

Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. What distinguishes them from other gases is that they absorb the wavelengths of radiation that a planet emits, resulting in the greenhouse effect. The Earth is warmed by sunlight, causing its surface to radiate heat, which is then mostly absorbed by greenhouse gases. Without greenhouse gases in the atmosphere, the average temperature of Earth's surface would be about −18 °C (0 °F), rather than the present average of 15 °C (59 °F).

Atmospheric methane is the methane present in Earth's atmosphere. The concentration of atmospheric methane is increasing due to methane emissions, and is causing climate change. Methane is one of the most potent greenhouse gases. Methane's radiative forcing (RF) of climate is direct, and it is the second largest contributor to human-caused climate forcing in the historical period. Methane is a major source of water vapour in the stratosphere through oxidation; and water vapour adds about 15% to methane's radiative forcing effect. The global warming potential (GWP) for methane is about 84 in terms of its impact over a 20-year timeframe, and 28 in terms of its impact over a 100-year timeframe.

The history of the scientific discovery of climate change began in the early 19th century when ice ages and other natural changes in paleoclimate were first suspected and the natural greenhouse effect was first identified. In the late 19th century, scientists first argued that human emissions of greenhouse gases could change Earth's energy balance and climate. The existence of the greenhouse effect, while not named as such, was proposed as early as 1824 by Joseph Fourier. The argument and the evidence were further strengthened by Claude Pouillet in 1827 and 1838. In 1856 Eunice Newton Foote demonstrated that the warming effect of the sun is greater for air with water vapour than for dry air, and the effect is even greater with carbon dioxide.

The atmospheric carbon cycle accounts for the exchange of gaseous carbon compounds, primarily carbon dioxide, between Earth's atmosphere, the oceans, and the terrestrial biosphere. It is one of the faster components of the planet's overall carbon cycle, supporting the exchange of more than 200 billion tons of carbon in and out of the atmosphere throughout the course of each year. Atmospheric concentrations of CO₂ remain stable over longer timescales only when there exists a balance between these two flows. Methane, Carbon monoxide (CO), and other human-made compounds are present in smaller concentrations and are also part of the atmospheric carbon cycle.

Increasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating. During 2019, about 60% of methane released globally was from human activities, while natural sources contributed about 40%. Reducing methane emissions by capturing and utilizing the gas can produce simultaneous environmental and economic benefits.

References

Ruddiman, W. F. (2005). Plows, Plagues, and Petroleum : how humans took control of climate . Princeton, N.J: Princeton University Press. ISBN 0-691-12164-8. pdf

Plows, Plagues and Petroleum

Contents

Synopsis

Critical assessment

See also

Notes

Related Research Articles

References

Further reading