Ancient civilizations emitted greenhouse gasses, too; the red and orange dots above
mark indirect measures of methane in the atmosphere over the past two millennia.
Scientists have thought that humans only started emitting significant quantities of greenhouse gasses in the 19th century, after the Industrial Revolution—and the fossil fuels that powered it—took hold. But a study in Nature today suggests that our history as heavy emitters stretches back much farther, to the charcoal fires of the Roman Empire and the intensive agriculture of Han China.
To examine carbon emissions past, the research team analyzed more than 50 ice cores from Greenland, gauging levels of the greenhouse gas methane in Earth’s atmosphere going back to 100 B.C. They looked at specific carbon signatures in the methane to determine whether it came from burning coal and other materials—meaning humans might have been involved—or a natural biological process, then used mathematical models to further narrow down manmade emissions from naturally occurring ones. Human emissions, they found, were noticeable, though minuscule compared to post-industrial levels; only perhaps 10% human methane emissions over the past 2,000 years were produced before 1800. For a time when there were far fewer people around, however, that’s still a lot of methane to be sending off into the atmosphere.
With Shark Week, the Discovery Channel’s annual paean to the ocean’s apex predators, in full swing, many of us have sharks on the brain. At Smithsonian, Megan Gambino interviewed ichthyologist George Burgess—curator of the International Shark Attack File, an archive of thousands of attacks spanning the last five centuries—about an unusual chapter of the animals’ past: Over the course of two weeks in July 1916, a great white shark attacked five people along the Jersey Shore, killing all but one. The bizarre string of attacks inspired the book, and later the film, Jaws.
Initially, however, as Burgess recounted in the interview, people didn’t even believe a shark was to blame:
The thinking was it couldn’t be a shark, because we don’t have sharks here. It must be a sea turtle. Someone suggested it was a school of turtles that was coming in and biting things. Of course, turtles don’t school, and they don’t bite human beings, but it sounded good. A killer whale was suggested as well. The theories abounded and were allowed to get out unchecked into the media simply because there was not a forceful scientific authority that really knew what was going on to step right in and try to level the conversation.
A page from the Anglo-Saxon Chronicle. The entry for
774 AD refers to a “red crucifix” appearing in the sky.
Earlier this month, researchers found that Japanese trees had preserved a centuries-old spike in the atmosphere’s proportion of carbon-14, apparently caused by a burst of cosmic rays that hit earth between 774 and 775 AD. But that left a perplexing mystery: the most likely source of that excess carbon-14 would be cosmic rays emitted by a supernova. But any supernova powerful enough to generate carbon-14 should have been visible to people alive then, and there was no known record of what should’ve been a pretty notable event.
Enter Jonathon Allen, a polymath undergraduate who majors in biochemistry and also has a deep interest in history. Allen dug around in a contemporary manuscript and found a reference to a “red crucifix” appearing in the sky in 774 AD. This celestial signal may have marked a supernova that birthed the cosmic rays and created the trees’ carbon-14 peak.
This might look like a lot of old coins, but they come from
a trove 35 times smaller than the most recent find.
Uncovering ancient buried treasure doesn’t require the skills to interpret a secret map or navigate a booby-trapped cave. All it took to turn up the largest hoard of Iron Age coins ever found in Europe were two metal detectors…and a lot of patience. After 30 years of searching, Reg Mead and Richard Miles discovered a cache of 30,000 to 50,000 gold and silver Celtic coins worth up to $15 million.
About three decades ago, Mead and Miles heard that a farmer had discovered some silver coins in a field on Jersey, a self-governing island in the English Channel. Although most people would dismiss the rumor, the two men were so intrigued that they started investigating with their metal detectors, a practice they continued through February of this year, when their long quest turned up 60 silver coins and one gold one. Still not satisfied, the men kept looking.
An 1865 painting by Frederic Edwin Church, possibly inspired by the aurora of 1859.
On September 1, 1859, the sky erupted in color: “alternating great pillars, rolling cumuli shooting streamers, curdled and wisped and fleecy waves—rapidly changing its hue from red to orange, orange to yellow, and yellow to white, and back in the same order to brilliant red,” read a New York Times account. This was the aurora seen around the world.
Meanwhile, the telegraph operators were perplexed to find that the system suddenly failed. None of the lines worked, and telegraph paper spontaneously caught on fire. The aurora and disconnected telegraphs were both the working of the largest solar storm recorded in history.
Most archaeologists dig up the past, examining artifacts for clues—but experimental archaeologists build the past from the ground up, testing out what they can make and do using the same tools and techniques ancient peoples did. Brandon Keim at Wired Science has compiled a fascinating collection of these studies, following scientists as they sail the South Pacific on rafts of balsa wood, hunt deer with flint-tipped spears, and build smoky fires to keep warm through the Scandinavian winter (above).
[See the rest at Wired Science.]
The city of Piraeus, in 2008
What’s the News: Chalk up another win for the ancient Greeks. The Greek historian and geographer Strabo wrote nearly 2,000 years ago that Piraeus, a small peninsula near Athens, had once been an island—and a new study in this month’s issue of Geology shows he was right.
It’s tough enough to play Dr. House with a living, breathing patient who’s right there in the room. It’s quite another thing to diagnose across distance and time. Yet some scientists find it irresistible to peek into the history books with the benefit of modern medical knowledge and try to crack the cases of historical figures who died too young. Was metal-nosed astronomer Tycho Brahe poisoned, for instance? And what caused Mozart’s demise? (It wasn’t Salieri.)
This week, researchers turn their detective eyes to the famed romantic composer Frederic Chopin, who left behind a wealth of lovely piano compositions when he died at 39 in 1849. Writing in Medical Humanities, a specialized edition of the British Medical Journal, Spanish scientists led by Manuel Varquez Caruncho argue that there’s an explanation for Chopin’s health woes and momentary hallucinations that his 19th century doctors and subsequent investigations overlooked: The composer had a particular type of epilepsy.
Chopin’s tendency to lapse out of consciousness was interpreted by his partner George Sand, pseudonym of the French novelist Aurore Dudevant, as “the manifestation of a genius full of sentiment and expression.” But in the analysis published this week, Spanish doctors say Chopin’s hallucinations may have been due to a temporal lobe epilepsy rather than the result of any sweeping artistic tendencies. [AP]
The Earth’s climate swings have disrupted human societies and civilizations throughout our species’ history; take examples like those in Jared Diamond’s Collapse. But are they also connected to one of the most famous collapses in the history books—the fall of the Roman Empire?
There are a host of reasons for the fall of Rome, researchers led by paleoclimatologist Ulf Büntgen write today in the journal Science. However, analyzing the climate records of the past 2,500 years reveals that changes to Europe’s climate coincided with the rise and fall of the famous civilization. Such a correlation could suggest that climate played some part in building the Romans up and in tearing them down.
Büntgen and colleagues collaborated with archaeologists to amass a database of more than 9,000 pieces of wood dating back 2,500 years. Samples came from both live trees and remains of buildings and other wooden artifacts, all from France and Germany. By measuring the width of annual growth rings in the wood, the researchers were able to determine temperature and precipitation levels on a year-by-year basis. [Discovery News]
The results of this unprecedented collection of climate data: In the third century B.C., when Rome fought the First and Second Punic wars against Carthage and began its ascent to Mediterranean empire, times were good. The rains fell, the temperatures were warm, and agriculture would have flourished. But by the third century A.D., the time when the Germanic invasions began to creep further into Roman territory, more droughts had come to Western Europe. This trend persisted into about the 6th century A.D.