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Javier E

Geology's Timekeepers Are Feuding - The Atlantic - 0 views

  • , in 2000, the Nobel Prize-winning chemist Paul Crutzen won permanent fame for stratigraphy. He proposed that humans had so throughly altered the fundamental processes of the planet—through agriculture, climate change, and nuclear testing, and other phenomena—that a new geological epoch had commenced: the Anthropocene, the age of humans.
  • Zalasiewicz should know. He is the chair of the Anthropocene working group, which the ICS established in 2009 to investigate whether the new epoch deserved a place in stratigraphic time.
  • In 2015, the group announced that the Anthropocene was a plausible new layer and that it should likely follow the Holocene. But the team has yet to propose a “golden spike” for the epoch: a boundary in the sedimentary rock record where the Anthropocene clearly begins.
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  • Officially, the Holocene is still running today. You have lived your entire life in the Holocene, and the Holocene has constituted the geological “present” for as long as there have been geologists.But if we now live in a new epoch, the Anthropocene, then the ICS will have to chop the Holocene somewhere. It will have to choose when the Holocene ended, and it will move some amount of time out of the purview of the Holocene working group and into that of the Anthropocene working group.
  • This is politically difficult. And right now, the Anthropocene working group seems intent on not carving too deep into the Holocene. In a paper published earlier this year in Earth-Science Reviews, the Anthropocene working group’s members strongly imply that they will propose starting the new epoch in the mid-20th century.
  • Some geologists argue that the Anthropocene started even earlier: perhaps 4,000 or 6,000 years ago, as farmers began to remake the land surface.“Most of the world’s forests that were going to be converted to cropland and agriculture were already cleared well before 1950,” says Bill Ruddiman, a geology professor at the University of Virginia and an advocate of this extremely early Anthropocene.
  • “Most of the world’s prairies and steppes that were going to be cleared for crops were already gone, by then. How can you argue the Anthropocene started in 1950 when all of the major things that affect Earth’s surface were already over?”Van der Pluijm agreed that the Anthropocene working group was picking 1950 for “not very good reasons.”“Agriculture was the revolution that allowed society to develop,” he said. “That was really when people started to force the land to work for them. That massive land movement—it’s like a landslide, except it’s a humanslide. And it is not, of course, as dramatic as today’s motion of land, but it starts the clock.”
  • This muddle had to stop. The Holocene comes up constantly in discussions of modern global warming. Geologists and climate scientists did not make their jobs any easier by slicing it in different ways and telling contradictory stories about it.
  • This process started almost 10 years ago. For this reason, Zalasiewicz, the chair of the Anthropocene working group, said he wasn’t blindsided by the new subdivisions at all. In fact, he voted to adopt them as a member of the Quaternary working group.“Whether the Anthropocene works with a unified Holocene or one that’s in three parts makes for very little difference,” he told me.In fact, it had made the Anthropocene group’s work easier. “It has been useful to compare the scale of the two climate events that mark the new boundaries [within the Holocene] with the kind of changes that we’re assessing in the Anthropocene. It has been quite useful to have the compare and contrast,” he said. “Our view is that some of the changes in the Anthropocene are rather bigger.”
  • Zalasiewicz said that he and his colleagues were going as fast as they could. When the working group group began its work in 2009, it was “really starting from scratch,” he told me.While other working groups have a large body of stratigraphic research to consider, the Anthropocene working group had nothing. “We had to spend a fair bit of time deciding whether the Anthropocene was geology at all,” he said. Then they had to decide where its signal could show up. Now, they’re looking for evidence that shows it.
  • This cycle of “glacials” and “interglacials” has played out about 50 times over the last several million years. When the Holocene began, it was only another interglacial—albeit the one we live in. Until recently, glaciers were still on schedule to descend in another 30,000 years or so.Yet geologists still call the Holocene an epoch, even though they do not bestow this term on any of the previous 49 interglacials. It get special treatment because we live in it.
  • Much of this science is now moot. Humanity’s vast emissions of greenhouse gas have now so warmed the climate that they have offset the next glaciation. They may even knock us out of the ongoing cycle of Ice Ages, sending the Earth hurtling back toward a “greenhouse” climate after the more amenable “icehouse” climate during which humans evolved.For this reason, van der Pluijm wants the Anthropocene to supplant the Holocene entirely. Humans made their first great change to the environment at the close of the last glaciation, when they seem to have hunted the world’s largest mammals—the wooly mammoth, the saber-toothed tiger—to extinction. Why not start the Anthropocene then?He would even rename the pre-1800 period “the Holocene Age” as a consolation prize:
  • Zalasiewicz said he would not start the Anthropocene too early in time, as it would be too work-intensive for the field to rename such a vast swath of time. “The early-Anthropocene idea would crosscut against the Holocene as it’s seen by Holocene workers,” he said. If other academics didn’t like this, they could create their own timescales and start the Anthropocene Epoch where they choose. “We have no jurisdiction over the word Anthropocene,” he said.
  • Ruddiman, the University of Virginia professor who first argued for a very early Anthropocene, now makes an even broader case. He’s not sure it makes sense to formally define the Anthropocene at all. In a paper published this week, he objects to designating the Anthropocene as starting in the 1950s—and then he objects to delineating the Anthropocene, or indeed any new geological epoch, by name. “Keep the use of the term informal,” he told me. “Don’t make it rigid. Keep it informal so people can say the early-agricultural Anthropocene, or the industrial-era Anthropocene.”
  • “This is the age of geochemical dating,” he said. Geologists have stopped looking to the ICS to place each rock sample into the rock sequence. Instead, field geologists use laboratory techniques to get a precise year or century of origin for each rock sample. “The community just doesn’t care about these definitions,” he said.
Javier E

Are we in the Anthropocene? Geologists could define new epoch for Earth - 0 views

  • If the nearly two dozen voting members of the Anthropocene Working Group (AWG), a committee of scientists formed by the International Commission on Stratigraphy (ICS), agree on a site, the decision could usher in the end of the roughly 12,000-year-old Holocene epoch. And it would officially acknowledge that humans have had a profound influence on Earth.
  • Scientists coined the term Anthropocene in 2000, and researchers from several fields now use it informally to refer to the current geological time interval, in which human activity is driving Earth’s conditions and processes.
  • Formalizing the Anthropocene would unite efforts to study people’s influence on Earth’s systems, in fields including climatology and geology, researchers say. Transitioning to a new epoch might also coax policymakers to take into account the impact of humans on the environment during decision-making.
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  • Defining the Anthropocene: nine sites are in the running to be given the ‘golden spike’ designation
  • Mentioning the Jurassic period, for instance, helps scientists to picture plants and animals that were alive during that time
  • “The Anthropocene represents an umbrella for all of these different changes that humans have made to the planet,”
  • Typically, researchers will agree that a specific change in Earth’s geology must be captured in the official timeline. The ICS will then determine which set of rock layers, called strata, best illustrates that change, and it will choose which layer marks its lower boundary
  • This is called the Global Stratotype Section and Point (GSSP), and it is defined by a signal, such as the first appearance of a fossil species, trapped in the rock, mud or other material. One location is chosen to represent the boundary, and researchers mark this site physically with a golden spike, to commemorate it.
  • “It’s a label,” says Colin Waters, who chairs the AWG and is a geologist at the University of Leicester, UK. “It’s a great way of summarizing a lot of concepts into one word.”
  • But the Anthropocene has posed problems. Geologists want to capture it in the timeline, but its beginning isn’t obvious in Earth’s strata, and signs of human activity have never before been part of the defining process.
  • “We had a vague idea about what it might be, [but] we didn’t know what kind of hard evidence would go into it.”
  • Years of debate among the group’s multidisciplinary members led them to identify a host of signals — radioactive isotopes from nuclear-bomb tests, ash from fossil-fuel combustion, microplastics, pesticides — that would be trapped in the strata of an Anthropocene-defining site. These began to appear in the early 1950s, when a booming human population started consuming materials and creating new ones faster than ever.
  • Why do some geologists oppose the Anthropocene as a new epoch?“It misrepresents what we do” in the ICS, says Stanley Finney, a stratigrapher at California State University, Long Beach, and secretary-general for the International Union of Geological Sciences (IUGS). The AWG is working backwards, Finney says: normally, geologists identify strata that should enter the geological timescale before considering a golden spike; in this case, they’re seeking out the lower boundary of an undefined set of geological layers.
  • Lucy Edwards, a palaeontologist who retired in 2008 from the Florence Bascom Geoscience Center in Reston, Virginia, agrees. For her, the strata that might define the Anthropocene do not yet exist because the proposed epoch is so young. “There is no geologic record of tomorrow,”
  • Edwards, Finney and other researchers have instead proposed calling the Anthropocene a geological ‘event’, a flexible term that can stretch in time, depending on human impact. “It’s all-encompassing,” Edwards says.
  • Zalasiewicz disagrees. “The word ‘event’ has been used and stretched to mean all kinds of things,” he says. “So simply calling something an event doesn’t give it any wider meaning.”
Javier E

Scientists identify vast underground ecosystem containing billions of micro-organisms |... - 0 views

  • Despite extreme heat, no light, minuscule nutrition and intense pressure, scientists estimate this subterranean biosphere is teeming with between 15bn and 23bn tonnes of micro-organisms, hundreds of times the combined weight of every human on the planet.
  • Researchers at the Deep Carbon Observatory say the diversity of underworld species bears comparison to the Amazon or the Galápagos Islands, but unlike those places the environment is still largely pristine because people have yet to probe most of the subsurface.
  • “It’s like finding a whole new reservoir of life on Earth,” said Karen Lloyd, an associate professor at the University of Tennessee in Knoxville. “We are discovering new types of life all the time. So much of life is within the Earth rather than on top of it.
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  • The team combines 1,200 scientists from 52 countries in disciplines ranging from geology and microbiology to chemistry and physics.
  • The results suggest 70% of Earth’s bacteria and archaea exist in the subsurface
  • “The strangest thing for me is that some organisms can exist for millennia. They are metabolically active but in stasis, with less energy than we thought possible of supporting life.”
  • Some microorganisms have been alive for thousands of years, barely moving except with shifts in the tectonic plates, earthquakes or eruption
  • these organisms are part of slow, persistent cycles on geological timescales.”
  • Underworld biospheres vary depending on geology and geography. Their combined size is estimated to be more than 2bn cubic kilometres, but this could be expanded further in the future
  • The researchers said their discoveries were made possible by two technical advances: drills that can penetrate far deeper below the Earth’s crust, and improvements in microscopes that allow life to be detected at increasingly minute levels.
  • The scientists have been trying to find a lower limit beyond which life cannot exist, but the deeper they dig the more life they find. There is a temperature maximum – currently 122C – but the researchers believe this record will be broken if they keep exploring and developing more sophisticated instruments.
  • Robert Hazen, a mineralogist at the Carnegie Institution for Science, said: “We must ask ourselves: if life on Earth can be this different from what experience has led us to expect, then what strangeness might await as we probe for life on other worlds?”
Javier E

Grand Old Planet - NYTimes.com - 1 views

  • Mr. Rubio was asked how old the earth is. After declaring “I’m not a scientist, man,” the senator went into desperate evasive action, ending with the declaration that “it’s one of the great mysteries.”
  • Reading Mr. Rubio’s interview is like driving through a deeply eroded canyon; all at once, you can clearly see what lies below the superficial landscape. Like striated rock beds that speak of deep time, his inability to acknowledge scientific evidence speaks of the anti-rational mind-set that has taken over his political party.
  • that question didn’t come out of the blue. As speaker of the Florida House of Representatives, Mr. Rubio provided powerful aid to creationists trying to water down science education. In one interview, he compared the teaching of evolution to Communist indoctrination tactics — although he graciously added that “I’m not equating the evolution people with Fidel Castro.
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  • What was Mr. Rubio’s complaint about science teaching? That it might undermine children’s faith in what their parents told them to believe.
  • What accounts for this pattern of denial? Earlier this year, the science writer Chris Mooney published “The Republican Brain,” which was not, as you might think, a partisan screed. It was, instead, a survey of the now-extensive research linking political views to personality types. As Mr. Mooney showed, modern American conservatism is highly correlated with authoritarian inclinations — and authoritarians are strongly inclined to reject any evidence contradicting their prior beliefs
  • it’s not symmetric. Liberals, being human, often give in to wishful thinking — but not in the same systematic, all-encompassing way.
  • We are, after all, living in an era when science plays a crucial economic role. How are we going to search effectively for natural resources if schools trying to teach modern geology must give equal time to claims that the world is only 6.000 years old? How are we going to stay competitive in biotechnology if biology classes avoid any material that might offend creationists?
  • then there’s the matter of using evidence to shape economic policy. You may have read about the recent study from the Congressional Research Service finding no empirical support for the dogma that cutting taxes on the wealthy leads to higher economic growth. How did Republicans respond? By suppressing the report. On economics, as in hard science, modern conservatives don’t want to hear anything challenging their preconceptions — and they don’t want anyone else to hear about it, either.
Emily Horwitz

Drought May Have Killed Sumerian Language | LiveScience - 1 views

  • A 200-year-long drought 4,200 years ago may have killed off the ancient Sumerian language, one geologist says.
  • no written accounts explicitly mention drought as the reason for the Sumerian demise, the conclusions rely on indirect clues.
  • his was not a single summer or winter, this was 200 to 300 years of drought," said Matt Konfirst, a geologist at the Byrd Polar Research Center.
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  • Sumerian culture disappeared around 4,000 years ago, and the Sumerian language went extinct soon after that.
  • geological records point to a long period of drier weather in the Middle East around 4,200 years ago, Konfirst said. The Red Sea and the Dead Sea had increased evaporation; water levels dropped at Lake Van in Turkey, and cores from marine sediments around that period indicate increased dust in the environment.
  • Around the same time, 74 percent of the ancient Mesopotamian settlements were abandoned, according to a 2006 study of an archaeological site called Tell Leilan in Syria. The populated area also shrank by 93 percent, he said.
  • great drought, two waves of marauding nomads descended upon the region, sacking the capital city of Ur. After around 2000 B.C., ancient Sumerian gradually died off as a spoken language in the region. For the next 2,000 years, the tongue lingered on as a dead written language, similar to Latin in the Middle Ages, but has been completely extinct since then, Konfirst said.
Javier E

Nate Silver, Artist of Uncertainty - 0 views

  • In 2008, Nate Silver correctly predicted the results of all 35 Senate races and the presidential results in 49 out of 50 states. Since then, his website, fivethirtyeight.com (now central to The New York Times’s political coverage), has become an essential source of rigorous, objective analysis of voter surveys to predict the Electoral College outcome of presidential campaigns. 
  • Political junkies, activists, strategists, and journalists will gain a deeper and more sobering sense of Silver’s methods in The Signal and the Noise: Why So Many Predictions Fail—But Some Don’t (Penguin Press). A brilliant analysis of forecasting in finance, geology, politics, sports, weather, and other domains, Silver’s book is also an original fusion of cognitive psychology and modern statistical theory.
  • Its most important message is that the first step toward improving our predictions is learning how to live with uncertainty.
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  • The second step is starting to understand why it is that big data, super computers, and mathematical sophistication haven’t made us better at separating signals (information with true predictive value) from noise (misleading information). 
  • Silver’s background in sports and poker turns out to be invaluable. Successful analysts in gambling and sports are different from fans and partisans—far more aware that “sure things” are likely to be illusions,
  • he blends the best of modern statistical analysis with research on cognition biases pioneered by Princeton psychologist and Nobel laureate in economics  Daniel Kahneman and the late Stanford psychologist Amos Tversky. 
  • One of the biggest problems we have in separating signal from noise is that when we look too hard for certainty that isn’t there, we often end up attracted to noise, either because it is more prominent or because it confirms what we would like to believe.
  • In discipline after discipline, Silver shows in his book that when you look at even the best single forecast, the average of all independent forecasts is 15 to 20 percent more accurate. 
  • Silver has taken the next major step: constantly incorporating both state polls and national polls into Bayesian models that also incorporate economic data.
  • Silver explains why we will be misled if we only consider significance tests—i.e., statements that the margin of error for the results is, for example, plus or minus four points, meaning there is one chance in 20 that the percentages reported are off by more than four. Calculations like these assume the only source of error is sampling error—the irreducible error—while ignoring errors attributable to house effects, like the proportion of cell-phone users, one of the complex set of assumptions every pollster must make about who will actually vote. In other words, such an approach ignores context in order to avoid having to justify and defend judgments. 
Sophia C

When Studies Are Wrong: A Coda - NYTimes.com - 0 views

  • All scientific results are, of course, subject to revision and refutation by later experiments. The problem comes when these replications don’t occur and the information keeps spreading unchecked. Continue reading the main story Related Coverage Raw Data: Hills to Scientific Discoveries Grow SteeperFEB. 17, 2014 Raw Data: New Truths That Only One Can SeeJAN. 20, 2014 D
  • Based on the number of papers in major journals, Dr. Ioannidis estimates that the field accounts for some 50 percent of published research.
  • Together that constitutes most of scientific research. The remaining slice is physical science — everything from geology and climatology to cosmology and particle physics. These fields have not received the same kind of scrutiny as the others. Is that because they are less prone to the problems Dr. Ioannides describe
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  • “This certainly increases the transparency, reliability and cross-checking of proposed research findings,” he wrote.
  • “There seems to be a higher community standard for ‘shaming’ reputations if people step out and make claims that are subsequently refuted.” Cold fusion was a notorious example. He also saw less of an aversion to publishing negative experimental results — that is, failed replications.
  • Almost anything might be suspected of causing cancer, but physicists are unlikely to propose conjectures that violate quantum mechanics or general relativity. But I’m not sure the difference is always that stark. Here is how I put it my blog post:
  • “I have no doubt that false positives occur in all of these fields,” he concluded, “and occasionally they may be a major problem.”I’ll be looking further into this matter for a future column and would welcome comments from scientists about the situation in their own domain.
  • problem comes when these replications don’t occur and the information keeps spreading unchecked.
carolinewren

Whoops! A creationist museum supporter stumbled upon a major fossil find. - The Washing... - 0 views

  • Adhering to the most extreme form of religious creationism, the exhibits "prove" that the Earth is only around 6,000 years old, and that humans and dinosaurs co-existed.
  • Unfortunately, Nernberg just dug up a 60-million-year-old fish
  • Local outlets report that the man is far from shaken by the bony fish, which he found while excavating a basement in Calgary.
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  • He just doesn't believe they're that old. And he's quite the fossil lover.
  • We all have the same evidence, and it’s just a matter of how you interpret it,”
  • “There’s no dates stamped on these things."
  • Just, you know, isotopic dating, basic geology, really shoddy stuff like that.
  • the science of dating fossils is not shaky -- at least not on the order of tens of millions of years of error -- so this fossil and the rocks around it really do give new earth creationism the boot.
  • But this can go down as one of the best examples ever of why it's downright impossible to convince someone who's "opposed" to evolution that it's a basic fact: If you think the very tenets of science are misguided, pretty much any evidence presented to you can be written off as fabricated or misinterpreted.
  • scientific community is thrilled and grateful for the find, and the University of Calgary will unveil the five fossils on Thursday.
  • It's an important point in Earth's evolutionary history, because new species were popping up all over to make up for the ecological niches dinos left behind.
  • Ironically, Nernberg's contributions at the Creation Science Museum are almost certainly what scientists have to thank for the find
Javier E

Researchers Propose Earth's 'Anthropocene' Age of Humans Began With Fallout and Plastic... - 0 views

  • we’ve left the Holocene behind — that’s the geological epoch since the end of the last ice age — and entered “a post-Holocene…geological age of our own making,” now best known as the Anthropocene.
  • the Anthropocene Working Group (because of my early writings, I’m a lay member), has moved substantially from asking whether such a transition has occurred to deciding when.
  • 1950 as the starting point, indicated by a variety of markers, including the global spread of carbon isotopes from nuclear weapon detonations starting in 1945 and the mass production and disposal of plastics.
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  • in the broadest sense we have to embrace the characteristics, good and bad, that make humans such a rare thing — a species that has become a planet-scale force.
  • Once you begin to get the many feedbacks bouncing off each other and bouncing off the Earth system, it’s going to be very hard to follow what’s going to happen, particularly biologically…. One could not imagine, at the very end of the Cretaceous, the beginning of the Tertiary, that the mammals — these itty-bitty little squeaky furry things, would take over – effectively taking the position that the dinosaurs held for so long. All we can say is that, for sure, it will be different. We’re going down a different trouser leg of history.
  • on whether it’s possible to have a “good Anthropocene.” Kolbert’s Twitter post last spring nicely captured their view:
  • Taking full ownership of the Anthropocene won’t be easy. The necessary feeling is a queasy mix of excitement and unease. I’ve compared it to waking up in the first car on the first run of a new roller coaster that hasn’t been examined fully by engineers.
  • That’s a very different sensation than, say, mourning the end of nature. It’s more a celebration, in a way — a deeper acceptance of our place on the planet, with all of our synthetic trappings, and our faults, as fundamentally natural.
  • There’s little predictability in how things will play out after this anthropogenic jolt, especially in the living world. [More on the “great acceleration” behind the jolt is here.]
  • “The way I would like to see it is in, say, 100 years in the future the London Geological Society will look back and consider this period…a transition from the lesser Anthropocene to the greater Anthropocene.”
  • Fully integrating this awareness into our personal choices and societal norms and policies will take time. It is “the great work,” as Thomas Berry put it.
  • Technology alone will not do the trick. Another keystone to better meshing humanity’s infinite aspirations with life on a finite planet will be slowly shifting value systems from the foundation up
  • Edward O. Wilson’s “Biophilia” was a powerful look outward at the characteristics of the natural world that we inherently cherish.
  • Now we need a dose of what I’ve taken to calling anthropophilia, as well.
  • We have to accept ourselves, flaws and all, in order to move beyond what has been something of an unconscious, species-scale pubescent growth spurt, enabled by fossil fuels in place of testosterone.
  • We’re stuck with “The World With Us.” It’s time to grasp that uncomfortable, but ultimately hopeful, idea.
Javier E

Was There a Civilization On Earth Before Humans? - The Atlantic - 0 views

  • When it comes to direct evidence of an industrial civilization—things like cities, factories, and roads—the geologic record doesn’t go back past what’s called the Quaternary period 2.6 million years ago
  • if we’re going back this far, we’re not talking about human civilizations anymore. Homo sapiens didn’t make their appearance on the planet until just 300,000 years or so ago. That means the question shifts to other species, which is why Gavin called the idea the Silurian hypothesis
  • could researchers find clear evidence that an ancient species built a relatively short-lived industrial civilization long before our own? Perhaps, for example, some early mammal rose briefly to civilization building during the Paleocene epoch about 60 million years ago. There are fossils, of course. But the fraction of life that gets fossilized is always minuscule and varies a lot depending on time and habitat. It would be easy, therefore, to miss an industrial civilization that only lasted 100,000 years—which would be 500 times longer than our industrial civilization has made it so far.
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  • Given that all direct evidence would be long gone after many millions of years, what kinds of evidence might then still exist? The best way to answer this question is to figure out what evidence we’d leave behind if human civilization collapsed at its current stage of development.
  • Now that our industrial civilization has truly gone global, humanity’s collective activity is laying down a variety of traces that will be detectable by scientists 100 million years in the future. The extensive use of fertilizer, for example
  • And then there’s all that plastic. Studies have shown increasing amounts of plastic “marine litter” are being deposited on the seafloor everywhere from coastal areas to deep basins and even in the Arctic. Wind, sun, and waves grind down large-scale plastic artifacts, leaving the seas full of microscopic plastic particles that will eventually rain down on the ocean floor, creating a layer that could persist for geological timescales.
  • Likewise our relentless hunger for the rare-Earth elements used in electronic gizmos. Far more of these atoms are now wandering around the planet’s surface because of us than would otherwise be the case. They might also show up in future sediments, too.
  • Once you realize, through climate change, the need to find lower-impact energy sources, the less impact you will leave. So the more sustainable your civilization becomes, the smaller the signal you’ll leave for future generations.
  • The more fossil fuels we burn, the more the balance of these carbon isotopes shifts. Atmospheric scientists call this shift the Suess effect, and the change in isotopic ratios of carbon due to fossil-fuel use is easy to see over the last century. Increases in temperature also leave isotopic signals. These shifts should be apparent to any future scientist who chemically analyzes exposed layers of rock from our era. Along with these spikes, this Anthropocene layer might also hold brief peaks in nitrogen, plastic nanoparticles, and even synthetic steroids
  • Fifty-six million years ago, Earth passed through the Paleocene-Eocene Thermal Maximum (PETM). During the PETM, the planet’s average temperature climbed as high as 15 degrees Fahrenheit above what we experience today. It was a world almost without ice, as typical summer temperatures at the poles reached close to a balmy 70 degrees Fahrenheit.
  • While there is evidence that the PETM may have been driven by a massive release of buried fossil carbon into the air, it’s the timescale of these changes that matter. The PETM’s isotope spikes rise and fall over a few hundred thousand years. But what makes the Anthropocene so remarkable in terms of Earth’s history is the speed at which we’re dumping fossil carbon into the atmosphere. There have been geological periods where Earth’s CO2 has been as high or higher than today, but never before in the planet’s multibillion-year history has so much buried carbon been dumped back into the atmosphere so quickly
  • So the isotopic spikes we do see in the geologic record may not be spiky enough to fit the Silurian hypothesis’s bill.
  • ronically, however, the most promising marker of humanity’s presence as an advanced civilization is a by-product of one activity that may threaten it most.
  • “How do you know we’re the only time there’s been a civilization on our own planet?”
Javier E

Scientists Discover Some of the Oldest Signs of Life on Earth - The Atlantic - 0 views

  • The Earth was formed around 4.54 billion years ago. If you condense that huge swath of prehistory into a single calendar year, then the 3.95-billion-year-old graphite that the Tokyo team analyzed was created in the third week of February. By contrast, the earliest fossils ever found are 3.7 billion years old; they were created in the second week of March.
  • Those fossils, from the Isua Belt in southwest Greenland, are stromatolites—layered structures created by communities of bacteria. And as I reported last year, their presence suggests that life already existed in a sophisticated form at the 3.7-billion-year mark, and so must have arisen much earlier. And indeed, scientists have found traces of biologically produced graphite throughout the region, in other Isua Belt rocks that are 3.8 billion years old, and in hydrothermal vents off the coast of Quebec that are at least a similar age, and possibly even older.
  • “As far back as the rock record extends—that is, as far back as we can look for direct evidence of early life, we are finding it. Earth has been a biotic, life-sustaining planet since close to its beginning.”
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  • living organisms concentrate carbon-12 in their cells—and when they die, that signature persists. When scientists find graphite that’s especially enriched in carbon-12, relative to carbon-13, they can deduce that living things were around when that graphite was first formed. And that’s exactly what the Tokyo team found in the Saglek Block—grains of graphite, enriched in carbon-12, encased within 3.95-billion-year-old rock.
  • the team calculated the graphite was created at temperatures between 536 and 622 Celsius—a range that’s consistent with the temperatures at which the surrounding metamorphic rocks were transformed. This suggests that the graphite was already there when the rocks were heated and warped, and didn’t sneak in later. It was truly OG—original graphite.
  • Still, all of this evidence suggests Earth was home to life during its hellish infancy, and that such life abounded in a variety of habitats. Those pioneering organisms—bacteria, probably—haven’t left any fossils behind. But Sano and Komiya hope to find some clues about them by analyzing the Saglek Block rocks. The levels of nitrogen, iron, and sulfur in the rocks could reveal which energy sources those organisms exploited, and which environments they inhabited. They could tell us how life first lived.
katherineharron

Four ways the Mars 2020 rover will pave the way for a manned mission - CNN - 0 views

  • When NASA's Mars 2020 rover lands on the Red Planet in February 2021, it will touch down in Jezero Crater, the site of a lake that existed 3.5 billion years ago. The next generation rover will build on the goals of previous robotic explorers by collecting the first samples of Mars, which would be returned to Earth at a later date.
  • "We're very much thinking about how Mars could be inhabited, how humans could come to Mars and make use of the resources that we have there in the Martian environment today," said Stack. "We send our robotic scouts first to learn about these other places, hopefully for us to prepare the way for us to go ourselves."
  • "Combining an understanding of the composition of the rocks, but also the very fine detail that we see in the rocks and the textures, can make a powerful case for ancient signs of life," Stack said. "We know that ancient Mars was habitable. But we haven't yet been able to show that we have signs, real signs, of ancient life yet. And with our instrument suite, we think we can make real advances towards that on the surface.
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  • "This is a huge endeavor for the human species, and it'll take cooperation from more than just our own space program," Stack said. "Once the resources are there, we can develop the technology. It's getting the buy-in from international partners and from our own space administration and government to really make this happen."
  • No matter the mission, sticking the landing is key for future success. The 2020 rover will land on Mars using the new Terrain Relative Navigation system, which allows the lander to avoid any large hazards in the landing zone.
  • Astronauts exploring Mars will need oxygen, but carting enough to sustain them on a spacecraft isn't viable. The Mars 2020 rover will carry MOXIE on board, or the Mars Oxygen In-Situ Resource Utilization Experiment.
  • Speaking of "The Martian," the events of the book and its film adaptation are set in motion when a surprise, devastating dust storm impacts astronauts on the Red Planet. Understanding the weather and environment on Mars will be crucial for determining the conditions astronauts will face.
  • For the first time, a surface mission will include a ground-penetrating radar instrument called RIMFAX, or Radar Imager for Mars' Subsurface Experiment. It will be able to peek beneath the surface and study Martian geology, looking for rock, ice and boulder layers. Scientists hope that RIMFAX will help them understand the geologic history of Jezero Crater, according to David Paige, principal investigator for the experiment at the University of California, Los Angeles.
Javier E

Scientists Can No Longer Ignore Ancient Flooding Tales - The Atlantic - 0 views

  • It wasn’t long after Henry David Inglis arrived on the island of Jersey, just northwest of France, that he heard the old story. Locals eagerly told the 19th-century Scottish travel writer how, in a bygone age, their island had been much more substantial, and that folks used to walk to the French coast. The only hurdle to their journey was a river—one easily crossed using a short bridge.
  • there had been a flood. A big one. Between roughly 15,000 and 6,000 years ago, massive flooding caused by melting glaciers raised sea levels around Europe. That flooding is what eventually turned Jersey into an island.
  • Rather than being a ridiculous claim not worthy of examination, perhaps the old story was true—a whisper from ancestors who really did walk through now-vanished lands
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  • That’s exactly what the geographer Patrick Nunn and the historian Margaret Cook at the University of the Sunshine Coast in Australia have proposed in a recent paper.
  • In their work, the pair describe colorful legends from northern Europe and Australia that depict rising waters, peninsulas becoming islands, and receding coastlines during that period of deglaciation thousands of years ago. Some of these stories, the researchers say, capture historical sea-level rise that actually happened—often several thousand years ago. For scholars of oral history, that makes them geomyths.
  • “The first time I read an Aboriginal story from Australia that seemed to recall the rise of sea levels after the last ice age, I thought, No, I don’t think this is correct,” Nunn says. “But then I read another story that recalled the same thing.
  • For Jo Brendryen, a paleoclimatologist at the University of Bergen in Norway who has studied the effects of deglaciation in Europe following the end of the last ice age, the idea that traditional oral histories preserve real accounts of sea-level rise is perfectly plausible.
  • During the last ice age, he says, the sudden melting of ice sheets induced catastrophic events known as meltwater pulses, which caused sudden and extreme sea-level rise. Along some coastlines in Europe, the ocean may have risen as much as 10 meters in just 200 years. At such a pace, it would have been noticeable to people across just a few human generations.
  • “These are stories based in trauma, based in catastrophe.”
  • That, he suggests, is why it may have made sense for successive generations to pass on tales of geological upheaval. Ancient societies may have sought to broadcast their warning: Beware, these things can happen!
  • the old stories still have things to teach us. As Nunn says, “The fact that our ancestors have survived those periods gives us hope that we can survive this.”
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