Category Archives: Human behavior

Chart of the day II: No atheist candidates, please


Or such is the consensus of 51 percent of American voters, who are more likely to vote for an atheist than they are for someone who doesn’t believe in any god at all.

From a new report [PDF] from the Pew Research Center:

BLOG Belief

Agriculture triggered early global warming


The earliest evidence of anthropogenic has now been pushed back seven millennia, Newswise reports:

A new analysis of ice-core climate data, archeological evidence and ancient pollen samples strongly suggests that agriculture by humans 7,000 years ago likely slowed a natural cooling process of the global climate, playing a role in the relatively warmer climate we experience today.

A study detailing the findings is published online in a recent edition of the journal Reviews of Geophysics, published by the American Geophysical Union.

“Early farming helped keep the planet warm,” said William Ruddiman, a University of Virginia climate scientist and lead author of the study, who specializes in investigating ocean sediment and ice-core records for evidence of climate fluctuations.

A dozen years ago, Ruddiman hypothesized that early humans altered the climate by burning massive areas of forests to clear the way for crops and livestock grazing. The resulting carbon dioxide and methane released into the atmosphere had a warming effect that “cancelled most or all of a natural cooling that should have occurred,” he said.

That idea, which came to be known as the “early anthropogenic hypothesis” was hotly debated for years by climate scientists, and is still considered debatable by some of these scientists. But in the new paper, Ruddiman and his 11 co-authors from institutions in the United States and Europe say that accumulating evidence in the past few years, particularly from ice-core records dating back to 800,000 years ago, show that an expected cooling period was halted after the advent of large-scale agriculture. Otherwise, they say, the Earth would have entered the early stages of a natural ice age, or glaciation period.

The Earth naturally cycles between cool glacial periods and warmer interglacial periods because of variations in its orbit around the sun. We currently are in an interglacial period, called the Holocene epoch, which began nearly 12,000 years ago.

In 2003, Ruddiman developed his early anthropogenic hypothesis after examining 350,000 years of climate data from ice cores and other sources. He found that during interglacial periods, carbon dioxide and methane levels decreased, cooling the climate and making way for a succeeding glacial period. But, only during the Holocene era, these gas levels rose, coinciding, he said, with the beginning of large-scale agriculture. He attributed the rise to this human activity, which began occurring millennia before the industrial era.

He attributed the rise in carbon dioxide emissions to the slash and burn techniques widely used by early farmers to make available large areas of land for crops. Ruddiman found that carbon dioxide levels rose beginning 7,000 years ago, and that methane began rising 5,000 years ago. He said this explains why a cooling trend didn’t happen that likely otherwise would have led to a new glacial period.

In the new study, Ruddiman and his colleagues have delved more deeply into the climate record using Antarctic ice-core data, dating back to 800,000 years ago. This use of a deeper historical data set clearly shows, they say, that the Holocene is unlike other interglacial periods in its abundance of carbon dioxide and methane, further implicating the impact of humans.

In the development of his hypothesis, Ruddiman and colleagues have drawn from numerous studies across scientific disciplines: climatology, anthropology, archaeology, paleoecology, and population dynamics, all to better understand how humans may have affected climate beyond the relatively recent industrial revolution and the widespread burning of fossil fuels.

They cite a recent study that also summarized archaeological studies and found that early rice irrigation, which releases methane gas to the atmosphere, explains most of the anomalously high rise in atmospheric methane beginning about 5,000 years ago. A proliferation of livestock farming during that time period also may explain part of the methane increase.

“After 12 years of debate about whether the climate of the last several thousand years has been entirely natural or in considerable part the result of early agriculture, converging evidence from several scientific disciplines points to a major anthropogenic influence,” Ruddiman said.

Map of the day: The U.S. urban/rural divide


From the U.S. Census Bureau [PDF]:

pctUrbanizedPressReleaseMap

Chart of the day: Moderate drinkers are happier


From Gallup, evidence that folks who drink moderately are happier that both teetotalers and heavy alcohol consumers:

BLOG Drikers

Headline of the day: Almost a fitting way to go


From the Independent, a warning that while we’ve trashed the earth with impunity, hazards lurk above:

Rise in space junk orbiting the Earth could ‘provoke armed conflict’, Russian scientists warn

Countries will be unable to tell whether damage to military satellites during collisions is caused by debris or deliberate attacks by other countries

Chart of the day: Bronze Age fairy tale roots


From “Comparative phylogenetic analyses uncover the ancient roots of Indo-European folktales” by Sara Graça da Silva of the Institute for the Study of Literature and Tradition of New University of Lisbon and Jamshid J. Tehrani of the Center for the Coevolution of Biology and Culture at England’s Durham University, published in the Royal Society Open Science Journal, which uses linguistic analysis to traces the origins of the “The Smith and the Devil,” a venerable folk tale found in many of the world’s traditions, back to roots in the Bronze Age [and click on the image to enlarge]:

Reconstructing tale descent histories. Example of an ancestral state reconstruction, showing ATU 330 ‘The Smith and the Devil’ traced on a consensus tree derived from 1000 Bayesian language trees. The proportion of black shading in each internal node represents the average probability of the tale being present in the corresponding hypothetical ancestor across the tree sample. The proportion of red shading in each node represents the number of trees in which the corresponding hypothetical ancestor was absent. Branches are colour-coded by linguistic subfamily. The oldest ancestral node that was reconstructed, Proto-Indo-European, is labelled ‘PIE’.

Reconstructing tale descent histories. Example of an ancestral state reconstruction, showing ATU 330 ‘The Smith and the Devil’ traced on a consensus tree derived from 1000 Bayesian language trees. The proportion of black shading in each internal node represents the average probability of the tale being present in the corresponding hypothetical ancestor across the tree sample. The proportion of red shading in each node represents the number of trees in which the corresponding hypothetical ancestor was absent. Branches are colour-coded by linguistic subfamily. The oldest ancestral node that was reconstructed, Proto-Indo-European, is labelled ‘PIE’.

Map of the day: Methane emissions in 2010


The latest available compilation from the European Union’s Emissions Database for Global Atmospheric Research [more data at the link]:

BLOG Methane