Posts Tagged ‘climate’
“Rather than heralding a new era of easy living, the Agricultural Revolution left farmers with lives generally more difficult and less satisfying than those of foragers”*…
Lest we wonder if climate change might have fundamental effects…
Why was agriculture invented? The long run advantages are clear: farming produced food surpluses that allowed population densities to rise, labor to specialize, and cities to be constructed. However, we still don’t know what motivated the transition in the short run. After 200,000 years of hunting and gathering, agriculture was invented independently at least seven times, on different continents, within a 7,000 year period. Archeologists agree that independent inventions occurred at least in the Fertile Crescent, Subsaharan Africa, North and South China, the Andes, Mexico, and North America. Moreover, the first farmers were shorter and had more joint diseases, suggesting that they ate less than hunter gatherers and worked more. Why would seven different human populations decide to adopt remarkably similar technologies, around the same time, and in spite of a lower standard of living?
I propose a new theory for the Neolithic Revolution, construct a model capturing its intuition, and test the resulting implications against a panel dataset of climate and adoption. I argue that the invention of agriculture was triggered by a large increase in climatic seasonality, which peaked approximately 12,000 years ago, shortly before the first evidence for agriculture appeared. This increase in seasonality was caused by well documented oscillations in the tilt of Earth’s rotational axis, and other orbital parameters. The harsher winters, and drier summers, made it hard for hunter-gatherers to survive during part of the year. Some of the most affected populations responded by storing foods, which in turn forced them to abandon their nomadic lifestyles, since they had to spend most of the year next to their necessarily stationary granaries, either stocking them, or drawing from them. While these communities were still hunter-gatherers, sedentarism and storage made it easier for them to adopt farming…
During the Neolithic Revolution, seven populations independently invented agriculture; a new paper argues that climate change was the cause: “The Ant and the Grasshopper: Seasonality and the Invention of Agriculture,” from Andrea Matranga (@andreamatranga)
[image above: source]
* Yuval Noah Harari, Sapiens: A Brief History of Humankind
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As we reap what we sow, we might spare a thought for Clarence Birdseye; he died on this date in 1956. An inventor, entrepreneur, and naturalist, he was the founder of the modern frozen food industry.
On Arctic trips as a field naturalist for the United States government, he noticed that freshly caught fish, when placed onto the Arctic ice and exposed to the icy wind and frigid temperatures, froze solid almost immediately. He learned, too, that the fish, when thawed and eaten, still had all its fresh characteristics. He concluded that quickly freezing certain items kept large crystals from forming, preventing damage to their cellular structure. In 1922, Clarence organized his own company, Birdseye Seafoods, Inc., New York City, where he began processing chilled fish fillets. He moved on to vegetables and other meats, then to the “fish stick,” along the way co-founding General Foods. In the end, Birdseye had over 300 patents for creating and handling frozen food.
“We’re not in Kansas anymore”*…
In March 2019, a violent tornado plowed through eastern Alabama, flattening houses and demolishing mobile homes. Twenty-three people were killed including four children, ages 10, 9, 8 and 6.
Exactly one year later, on March 3, 2020, a tornado gusting at 170 mph ripped through central Tennessee, killing 19 people. Four of the victims were children between the ages of 2 and 7.
The twisters spiraled along the ground for only minutes, but they are the two deadliest natural disasters in the United States since the start of 2019. They received fleeting national attention.
The mortal storms illustrate an alarming trend that is overlooked amid concern about hurricanes, wildfires and floods: Tornadoes are increasingly occurring in the Southeast, where they are twice as deadly as tornadoes elsewhere in the United States…
A shift of tornado activity from the Great Plains to the Southeast has brought heightened danger by concentrating twisters in a far more perilous landscape — one covered by forest that conceals tornadoes and is filled with mobile homes that are easily demolished…
Tornado Alley has moved from the Great Plains to the Southeast: “Migrating tornadoes are the nation’s deadliest disasters.”
* Dorothy, The Wizard of Oz
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As we contemplate the consequences of climate change, we might recall that it was on this date in 1896 that the Cedar Keys Hurricane finally disapated. Having passed as a tropical storm through the Lesser Antilles on September 22 (the earliest known activity), it grew to hurricane strength over Cuba, then passed on to Florida, over the Keys. Before being absorbed into another low pressure area, it made its way to southern New York State, where it finally gave out.
Its winds stayed high throughout its journey, and it was prodigiously wet: it left 19.96 inches at Glennville, Georgia, caused flash floods in the Shenandoah Valley, left the White House grounds in a wreck, and downed trees at the Gettysburg Battlefield. It is estimated to have caused 130 deaths and $1.5 million in damage (in 1896 dollars, which would be about $46 million today).
“Round and round they went with their snakes, snakily”*…
If pythons are the snake that ate the Everglades, the apocryphal legend of their takeover begins with an appropriately cinematic opening scene. In 1992, Hurricane Andrew plowed into the state, killing 65 people and leveling thousands of homes, as well as—so the story goes—a Burmese python breeding facility.
The reality of their introduction to the area may be less exciting. “The scientific thinking, I believe, is that they were probably animals that were discarded by pet owners deep down into the Everglades,” said Steve Johnson, an associate professor of wildlife ecology and conservation at the University of Florida.
The population of Burmese pythons in the Everglades is impossible to measure with much accuracy. Since the first reported sighting of one in the wild in Florida in 1979, their numbers have exploded. Estimates from the USGS indicate there could be tens of thousands to hundreds of thousands of them in South Florida. Regardless of their actual population size, their impact is clear: pythons have decimated biodiversity in the area. The hungry snakes will consume almost any animal in their path. They seize their prey using sharp, rear-facing fangs that are long enough to pierce a hunter’s arm. Then the snake coils around its victim, constricting the animal until it’s dead. Some hunters, to protect their lower legs from bites, wear camouflage-patterned snake gaiters, light armor that’s similar to shin guards worn by soccer players. But most go without, preferring intuition and quick reflexes over adding another layer of clothing to sweat through in the muggy glades.
To stem the tide of invasive species from the exotic-pet trade, the FWC holds amnesty days that allow pet owners to surrender animals to the agency without penalty. Although most pets that get released into the glades don’t survive, some outlier species like the Burmese python become established in their new ecosystems.
In this case, “established” sounds like an understatement. Pythons have taken over. Everything else has become prey. Since 2003, rabbit populations have disappeared from USGS study areas. Foxes, raccoons, possums, bobcats, and other species are all but gone. Pythons devoured the mammals and have moved on to birds, other reptiles, and possibly fish. The snakes can bring down animals as large as deer—which can either struggle and tear themselves away or become dinner—and even alligators.
Scientists have long suspected that pythons were consuming whole populations of small mammals in the Everglades and have made efforts at estimating the impacts. But exact population counts are impossible in such a vast wilderness. In a 2015 study led by Robert McCleery at the University of Florida, researchers translocated marsh rabbits into an area of the Everglades inhabited by a large number of pythons. At first the rabbits survived. Then temperatures began to rise, and with the warming weather, pythons slithered out of hiding and began to feast. In one year, they had eaten 77 percent of the rabbits…
Pythons are devouring native animal life in the unique ecosystem of South Florida. To help solve the problem, Florida Fish and Wildlife officials have turned to amateur and professional hunters to round up the reptiles in a wild competition called the Python Bowl: “The Misunderstood Python Hunters Saving the Everglades.”
* Brave New World
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As we ruminate on reptiles, we might recall that it was on this date in 1780 that a combination of thick smoke, fog, and heavy cloud cover caused so complete a darkness to fall on Eastern Canada and the New England area of the United States that candles were needed at noon. The drear, known as “New England’s Dark Day,” did not disburse until the following evening.
“In a series of forms graduating insensibly from some apelike creature to man as he now exists, it would be impossible to fix on any definite point where the term ‘man’ ought to be used”*…
Homo sapiens finger bone, dating back some 86,000 years, found at a site called Al Wusta in Saudi Arabia
Darwin turns out to right about the difficulty of dating the emergence of man, not only for the reason he intended (that our emergence from prior species was so gradual as to be indetectable as an “event”) but also because it’s turning out to be difficult to date the earliest examples we can agree are “man” and to figure out when they reached the places they settled…
The Nefud Desert is a desolate area of orange and yellow sand dunes. It covers approximately 25,000 square miles of the Arabian Peninsula. But tens of thousands of years ago, this area was a lush land of lakes, with a climate that may have been kinder to human life.
On a January afternoon in 2016, an international team of archaeologists and paleontologists was studying the surface of one ancient lake bed at a site called Al Wusta in the Nefud’s landscape of sand and gravel. Their eyes were peeled for fossils, bits of stone tools, and any other signs that might remain from the region’s once-verdant past.
Suddenly, Iyad Zalmout, a paleontologist working for the Saudi Geological Survey, spotted what looked like a bone. With small picks and brushes, he and his colleagues removed the find from the ground.
“We knew it [was] important,” Zalmout recalled in an email. It was the first direct evidence of any large primate or hominid life in the area. In 2018, lab tests revealed that this specimen was a finger bone from an anatomically modern human who would have lived at least 86,000 years ago.
Prior to this Al Wusta discovery, evidence in the form of stone tools had suggested some human presence in the Nefud between 55,000 and 125,000 years ago. To anthropologists, “human” and “hominin” can mean any of a number of species closely related to our own. The finger bone was the oldest Homo sapiens find in the region.
The bone’s dating contradicts a well-established narrative in the scientific community. Findings, particularly from the area of modern-day Israel, Jordan, and Lebanon, known as the Levant region, have led to the understanding that H. sapiens first made their way out of Africa no earlier than 120,000 years ago, likely migrating north along the Mediterranean coast. These people settled in the Levant and their descendants—or those from a subsequent early human migration out of Africa—traveled into Europe tens of thousands of years later.
Only later, that story goes, did they journey into parts of Asia, such as Saudi Arabia. By some estimates, then, anatomically modern humans would not have been in what is now Al Wusta until about 50,000 years ago.
The fingerbone, then, adds a twist to the tale of how and when our species left the African continent and, with many starts and stops, populated much of the rest of the earth. A new crop of discoveries, particularly from Asia, suggest that modern humans first left Africa some 200,000 years ago, taking multiple different routes…
Politics, geography, and tradition have long focused archaeological attention on the evolution of Homo sapiens in Europe and Africa. Now, new research is challenging old ideas by showing that early human migrations unfolded across Asia far earlier than previously known: “Will Asia Rewrite Human History?”
* Charles Darwin, The Descent of Man
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As we return to roots, we might spare a thought for Jean-Léon-François Tricart; he died on this date in 2003. A physical geographer and climatic geomorphologist known for his extensive regional studies in numerous countries of Africa.
Tricart was a pioneer in many fields of physical geography including the study of a phenomenon central to the migration of early Homo Sapiens, the major dynamic role of climate in landscape evolution.
“Civilization is a race between disaster and education”*…
One of the creepier conclusions drawn by scientists studying the Anthropocene—the proposed epoch of Earth’s geologic history in which humankind’s activities dominate the globe—is how closely today’s industrially induced climate change resembles conditions seen in past periods of rapid temperature rise.
“These ‘hyperthermals,’ the thermal-maximum events of prehistory, are the genesis of this research,” says Gavin Schmidt, climate modeler and director of the NASA Goddard Institute for Space Studies. “Whether the warming was caused by humans or by natural forces, the fingerprints—the chemical signals and tracers that give evidence of what happened then—look very similar.”
The canonical example of a hyperthermal is the Paleocene–Eocene Thermal Maximum (PETM), a 200,000-year period that occurred some 55.5 million years ago when global average temperatures rose by 5 to 8 degrees Celsius (about 9 to 14 degrees Fahrenheit). Schmidt has pondered the PETM for his entire career, and it was on his mind one day in his office last year when the University of Rochester astrophysicist Adam Frank paid him a visit.
Frank was there to discuss the idea of studying global warming from an “astrobiological perspective”—that is, investigating whether the rise of an alien industrial civilization on an exoplanet might necessarily trigger climate changes similar to those we see during Earth’s own Anthropocene. But almost before Frank could describe how one might search for the climatic effects of industrial “exocivilizations” on newly discovered planets, Schmidt caught him up short with a surprising question: “How do you know we’re the only time there’s been a civilization on our own planet?”
Frank considered a moment before responding with a question of his own: “Could we even tell if there had been an industrial civilization [long before this one]?”
Their subsequent attempt to address both questions has yielded a provocative paper on the possibility Earth might have spawned more than one technological society during its 4.5-billion-year history. And if indeed some such culture arose on Earth in the murky depths of geologic time, how might scientists today discern signs of that incredible development? Or, as the paper put it: “If an industrial civilization had existed on Earth many millions of years prior to our own era, what traces would it have left and would they be detectable today?”…
The entire fascinating piece at “Could an Industrial Prehuman Civilization Have Existed on Earth before Ours?”
* H. G. Wells
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As we ponder predecessors, we might recall hat it was on this date in 1974 that Nature published a paper by F. Sherwood Rowland documenting his discovery that chlorofluorocarbons (like freon in aerosols and refrigeration units) contribute to ozone depletion.
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