LC8C. Stay Current—Highs and Lows Over the Past 750 Million Years

2023-07-12. Massive lava outburst may have led to Snowball Earth. [] By Maia Wei-Haas, Science. Excerpt: About 717 million years ago, a climate catastrophe struck the planet, as temperatures plunged and glaciers enveloped the globe. The cause of this “Snowball Earth” episode has been mysterious, but it took place around the same time as a massive outburst of volcanism. Many researchers thought there might be a connection. But the timing was uncertain. Now, more precise dates, reported last month in Earth and Planetary Science Letters (EPSL) and in November 2022 in Science Advances, show the eruptions preceded the Snowball Earth event by 1 million to 2 million years. The lag points to a particular way the fire could have triggered the ice: through a chemical alteration of the fresh volcanic rocks known as weathering, which sucks carbon dioxide (CO2) from the atmosphere, turning down the planetary thermostat. The studies highlight the power of weathering as a key driver behind shifts in Earth’s climate, and how components of the planet as disparate as rocks and the atmosphere are inextricably linked, says EPSL study co-author Galen Halverson, a sedimentary geologist at McGill University. …Geoscientists debating the cause of the so-called Sturtian glaciation, which lasted 57 million years, have pointed to a number of possibilities—meteorite strikes, biologic activity, shifts in Earth’s orbit, and more. But recent studies have zeroed in on one of the largest volcanic outbursts ever, preserved today across northern Canada in what’s called the Franklin large igneous province (LIP). The eruptions spewed lava across an area at least the size of Argentina—and perhaps bigger than China….

2023-04-04. Life may have survived far north of equator during ‘Snowball Earth’. [] By Adam Mann, Science. Excerpt: More than 600 million years ago, the planet was frozen from pole to pole, covered in half-kilometer-thick ice sheets that darkened every ocean. How sea life clung on during Snowball Earth, as this inhospitable period is known, has long been a mystery. A new study bolsters the idea that the global glaciation wasn’t all encompassing. Geochemical evidence from ancient rocks suggests zones of open ocean may have been present north of the Tropic of Cancer, a region that was previously considered too cold to host life during this period. “There’s a habitable zone,” says Shuhai Xiao, a geobiologist at the Virginia Polytechnic Institute and State Universityand co-author of the new work. And it’s “perhaps wider than previously thought.” …Climate models since the 1960s have shown how planetary deep freezes can arise from a simple feedback loop. When temperatures drop, Earth’s ice caps expand, reflecting sunlight and creating further cooling. If the ice manages to creep to roughly 30° to 40° latitude—about where North Africa and the continental United States are today—the global climate enters a runaway freezing cycle and glaciers end up covering the entire planet within a few hundred years. The geological record indicates Earth has experienced at least two such periods. The most recent one is known as the Marinoan Ice Age, between 654 million and 635 million years ago. Life was limited to the oceans and large creatures had yet to evolve, but fossils show that microscopic eukaryotes such as algae lived before and after the episode….

2022-09-12. Mega-eruptions linked to most mass extinctions over past 500 million years. [] By Robert Sanders, UC Berkeley News. Excerpt: Mass extinctions litter the history of life on Earth, with about a dozen known in addition to the five largest ones — the last of which, at the end of the Cretaceous Period 66 million years ago, killed off the dinosaurs and 70% of all life on Earth. A new study, led by scientists at Dartmouth College in New Hampshire, concludes that most of these mass extinctions had one thing in common: They occurred after mega-eruptions that spewed volcanic lava and toxic gases for hundreds of thousands of years, and some for as long as a million years. The analysis linking mass extinctions throughout Earth’s history with major eruptions, characterized by lava and gas spilling from perhaps dozens of volcanoes and long fissure vents, confirms what many geologists have suspected for years. The most well-known mass extinction, referred to as the Cretaceous-Paleogene (K-Pg) extinction, was famously tied to a comet or asteroid impact in the Caribbean, but geologists have since found that the impact was preceded by a long period of eruptions in India that left behind flood basalts known today as the Deccan Traps. Massive amounts of sulfur dioxide emitted during the long-term eruption would have cooled the planet and caused the massive die-off seen in the fossil record.…

2021-09-27. Volcanic Eruptions Helped Dinosaurs Dominate Planet Earth. Source: By Sam Jones, The New York Times. Excerpt: Massive eruptions transformed the climate in the Triassic era, creating the conditions in which dinosaurs diversified into many more species. …For decades, scientists argued over whether volcanoes or an asteroid caused dinosaurs’ abrupt extinction some 65 million years ago. It wasn’t until 2010 that an international panel of experts formally declared that it was the space rock, and not giant eruptions, that was the primary cause of dino demise. And now a team of researchers is presenting the most compelling evidence yet that massive volcanic events likely helped the dinosaurs take over the planet, at least in another era. Their results were published Monday in the Proceedings of the National Academy of Sciences.… []

2021-08-19. Massive volcanoes could cool Earth more in a warming world. By Paul Voosen, Science Magazine. Excerpt: …Before humanity started in on its planet-altering course, volcanoes were one of the biggest climate players. Over the long term, they belched carbon dioxide from Earth’s interior, causing warming. But in the short term, their sulfur gases often react with water to form highly reflective particles called sulfates, triggering spells of global cooling. Dark smudges of ash littering ice cores—our best evidence of these early eruptions—are a dim reflection of the wild weather left in their wake. But the opposite is also true, it turns out: Climate can have a big impact on volcanoes. In the new study, Thomas Aubry, a geophysicist at the University of Cambridge, and colleagues combined computer simulations of idealized volcanic eruptions with a global climate model. They simulated the response to plumes released from midsize and large volcanoes both in historical conditions and by 2100, in a scenario when Earth is predicted to warm very rapidly. …ultramassive eruptions would still be able to punch through to the stratosphere; what’s more, their gases would actually reach higher and travel faster than in the present climate, amplifying their cooling effect by 15%, the researchers report this month in Nature Communications. The reasons why come down to the bizarro world that is the stratosphere, Aubry says.… [] See also See also Eos article – Anticipating Climate Impacts of Major Volcanic Eruptions.

2021-03-30. Red Rocks: Using Color to Understand Climate Change. By Ria Mazumdar, Eos/AGU. Excerpt: A recent study on hematite formation during the Triassic may help predict the effects of climate change on contemporary monsoonal environments. …conventional understanding attributes redness in the rock formations to diagenesis, a process of oxidation that occurs well after rocks are formed. …Lepre and his colleagues examined part of a 518-meter-long rock core from the Chinle Formation in Petrified Forest National Park in Arizona. Using diffuse reflectance spectroscopy, they obtained the wavelengths of various colors to find the concentration of hematite as well as grain size, which pushes the color to be more blue or red. (A more arid climate corresponds to a more reddish hue.) By looking at color cycles recorded in the rock formations, the team evaluated climate behavior during the Late Triassic, about 216 million to 213 million years ago…. []
2020-11-18. Burning Fossil Fuels Helped Drive Earth’s Most Massive Extinction. By Lucas Joel, The New York Times. Excerpt: Paleontologists call it the Permian-Triassic mass extinction, but it has another name: “the Great Dying.” It happened about 252 million years ago, and, over the course of just tens of thousands of years, 96 percent of all life in the oceans and, perhaps, roughly 70 percent of all land life vanished forever. The smoking gun was ancient volcanism in what is today Siberia, where volcanoes disgorged enough magma and lava over about a million years to cover an amount of land equivalent to a third or even half of the surface area of the United States. But volcanism on its own didn’t cause the extinction. The Great Dying was fueled, two separate teams of scientists report in two recent papers, by extensive oil and coal deposits that the Siberian magma blazed through, leading to combustion that released greenhouse gases like carbon dioxide and methane. “There was lots of oil, coal and carbonates formed before the extinction underground near the Siberian volcanism,” said Kunio Kaiho, a geochemist at Tohoku University in Sendai, Japan, and the lead author of one of the studies, published this month in Geology, which presented evidence for the burning of ancient fossil fuels by magma. “We discovered two volcanic combustion events coinciding with the end-Permian land extinction and marine extinction.” The findings solidify the Great Dying as one of the best examples that we have from Earth’s history of what a changing climate can do to life on our planet…. [

2020-07-14. Ancient Sea Levels in South Africa May Offer Modern Analogues. By Aaron Sidder, Eos/AGU. Excerpt: The concentration of carbon dioxide in Earth’s atmosphere as of June 2020 exceeds 416 parts per million, a level not seen since the mid-Pliocene warm period approximately 3 million years ago. Indeed, the entire Pliocene (5.33–2.58 million years ago) serves as a potential analogue for our present and future climate. …Geological proxies like fossilized flora and fauna indicate that temperatures during the Pliocene were about 3°F–5°F (2.7°C–4.0°C) hotter than those in the preindustrial era. Coastal rocks and sediments can also help identify the Pliocene’s elevated sea levels from a time when polar ice extents were drastically smaller than today. …Three of the 17 surveyed sites provided reliable age data, establishing that average sea levels during the Pliocene were between 15 and 30 meters higher than the present waterline…. []  

2020-06-10. Familiar Culprit May Have Caused Mysterious Mass Extinction. By Shannon Hall, The New York Times. Excerpt: It has long been our planet’s greatest and oldest murder mystery. Roughly 445 million years ago, around 85 percent of all marine species disappeared in a geologic flash known as the Late Ordovician mass extinction. But scientists have long debated this whodunit, in contrast to clearer explanations for Earth’s other mass extinctions. …“The Ordovician one has always been a little bit of an oddball,” said Stephen Grasby of the Geological Survey of Canada. Now he and David Bond of the University of Hull in England say they have cracked the case in a study published last month in the journal Geology. Widespread volcanic eruptions unleashed enough carbon dioxide to heat up the planet and trigger two pulses of extinction separated by 1 million years, they report. If true, it places the first grand wipeout of life on Earth in good company: Many of the other major mass extinctions are also thought to be victims of global warming…. []. 

2020-05-27. No asteroids needed: ancient mass extinction tied to ozone loss, warming climate. By Paul Voosen, Science Magazine. Excerpt:  The end of the Devonian period, 359 million years ago, was an eventful time: Fish were inching out of the ocean, and fernlike forests were advancing on land. The world was recovering from a mass extinction 12 million years earlier, but the climate was still chaotic, swinging between hothouse conditions and freezes so deep that glaciers formed in the tropics. And then, just as the planet was warming from one of these ice ages, another extinction struck, seemingly without reason. Now, spores from fernlike plants, preserved in ancient lake sediments from eastern Greenland, suggest a culprit: The planet’s protective ozone layer was suddenly stripped away, exposing surface life to a blast of mutation-causing ultraviolet (UV) radiation. Just as the extinction set in, the spores became misshapen and dark, indicating DNA damage, John Marshall, a palynologist at the University of Southampton, and his co-authors say in a paper published today in Science Advances []. It’s evidence, he says, that “all of the ozone protection is gone.” Scientists have long believed—at least before humanity became a force for extinction—that there were just two ways to wipe out life on Earth: an asteroid strike or massive volcanic eruptions. But 2 years ago, researchers found evidence that in Earth’s worst extinction—the end-Permian, 252 million years ago—volcanoes lofted Siberian salt deposits into the stratosphere, where they might have fed chemical reactions that obliterated the ozone layer and sterilized whole forests. Now, spores from the end-Devonian make a compelling case that, even without eruptions, a warming climate can deplete the ozone layer, says Lauren Sallan, a paleobiologist at the University of Pennsylvania. ….  [

2020-03-20. Basalts Turn Carbon into Stone for Permanent Storage. By Kimberly M. S. Cartier. Eos/AGU. Excerpt: Scientists have shown that mineral carbonation can permanently capture and store carbon quickly enough and safely enough to rise to the challenge of climate change. In carbon storage experiments tied to geothermal power plants in Iceland, 90% of injected carbon dioxide (CO2) transformed into minerals in just 2 years. Standard carbon storage methods can take thousands of years to do the same. “We are basing our methods on this natural process which is part of the big carbon cycle where all carbon on Earth derives from and ends up in rocks,” said one of the lead researchers, Sandra Snæbjörnsdóttir. She is the head of CO2 mineral storage at CarbFix []…. [
2019-12-19. Scientists have discovered the world’s oldest forest—and its radical impact on life. By Colin Barras, Science Magazine. 

2019-09-18. Veil of dust from ancient asteroid breakup may have cooled Earth. By Joshua Sokol, Science Magazine. [] Excerpt: Faced with a dangerously warming world, would-be geoengineers have dreamed up ways to quickly turn down the heat. One proposed technique: spreading a veil of dust that would sit in space or Earth’s atmosphere and reflect sunlight. Researchers say they have now found evidence for a similar experiment that played out naturally, 466 million years ago, when an asteroid out in space exploded into bits. Dust from the breakup blanketed the planet, says Birger Schmitz, a geologist at Lund University in Sweden, plunging it into an ice age that was soon followed by an explosion in animal life. The ancient episode offers both encouragement and caution for geoengineers. If Schmitz is right, it dramatically demonstrates how dust can cool the planet. But the deep freeze is a lesson in potential unintended consequences…. 

2019-05-22. A 500-million-year survey of Earth’s climate reveals dire warning for humanity. By Paul Voosen, Science Magazine. [] Excerpt: When it opens next month, the revamped fossil hall of the Smithsonian Institution’s National Museum of Natural History in Washington, D.C., will be more than a vault of dinosaur bones. It will show how Earth’s climate has shifted over the eons, driving radical changes in life, and how, in the modern age, one form of life—humans—is, in turn, transforming the climate. To tell that story, Scott Wing and Brian Huber, a paleobotanist and paleontologist, respectively, at the museum, wanted to chart swings in Earth’s average surface temperature over the past 500 million years or so. The two researchers also thought a temperature curve could counter climate contrarians’ claim that global warming is no concern because Earth was much hotter millions of years ago. Wing and Huber wanted to show the reality of ancient temperature extremes—and how rapid shifts between them have led to mass extinctions. Abrupt climate changes, Wing says, “have catastrophic side effects that are really hard to adapt to.” But actually making the chart was unexpectedly challenging—and triggered a major effort to reconstruct the record. Although far from complete, the research is already showing that some ancient climates were even more extreme than was thought….

2019-04-02. Ancient ‘Snowball Earth’ thawed out in a flash. By Lucas Joel, Science Magazine. [] Excerpt: More than half a billion years ago, our planet was a giant snowball hurtling through space. Glaciers blanketed the globe all the way to the equator in one of the mysterious “Snowball Earth” events geologists think occurred at least twice in Earth’s ancient past. Now, scientists have found that the final snowball episode likely ended in a flash about 635 million years ago—a geologically fast event that may have implications for today’s human-driven global warming. The ice, which built up over several thousand years, “melted in no more than 1 million years,” says Shuhai Xiao, a paleobiologist at Virginia Polytechnic Institute and State University in Blacksburg who was part of the team that made the discovery. That’s the blink of an eye in our planet’s 4.56-billion-year history, suggesting the globe reached a sudden tipping point, Xiao says. Although the team doesn’t know for certain what caused it, carbon dioxide emitted by ancient volcanoes may have triggered a greenhouse event, causing the ice sheets to thaw rapidly….

2018-12-28. Rise of carbon dioxide–absorbing mountains in tropics may set thermostat for global climate. By Paul Voosen, Science Magazine. [] Excerpt: Many mountains in Indonesia and neighboring Papua New Guinea consist of ancient volcanic rocks from the ocean floor that were caught in a colossal tectonic collision between a chain of island volcanoes and a continent, and thrust high. Lashed by tropical rains, these rocks hungrily react with CO2 and sequester it in minerals. That is why, with only 2% of the world’s land area, Indonesia accounts for 10% of its long-term CO2 absorption. Its mountains could explain why ice sheets have persisted, waxing and waning, for several million years (although they are now threatened by global warming). Now, researchers have extended that theory, finding that such tropical mountain-building collisions coincide with nearly all of the half-dozen or so significant glacial periods in the past 500 million years. “These types of environments, through time, are what sets the global climate,” said Francis Macdonald, a geologist at the University of California, Santa Barbara, when he presented the work this month at a meeting of the American Geophysical Union in Washington, D.C. If Earth’s climate has a master switch, he suggests, the rise of mountains like Indonesia’s could be it…. 

2018-12-07. The Planet Has Seen Sudden Warming Before. It Wiped Out Almost Everything. By Carl Zimmer, The New York Times. [] Excerpt: In some ways, the planet’s worst mass extinction — 250 million years ago, at the end of the Permian Period — may parallel climate change today. … Some 252 million years ago, Earth almost died. In the oceans, 96 percent of all species became extinct. It’s harder to determine how many terrestrial species vanished, but the loss was comparable. This mass extinction, at the end of the Permian Period, was the worst in the planet’s history, and it happened over a few thousand years at most — the blink of a geological eye. On Thursday, a team of scientists offered a detailed accounting of how marine life was wiped out during the Permian-Triassic mass extinction. Global warming robbed the oceans of oxygen, they say, putting many species under so much stress that they died off. And we may be repeating the process, the scientists warn. If so, then climate change is “solidly in the category of a catastrophic extinction event,” said Curtis Deutsch, an earth scientist at the University of Washington and co-author of the new study, published in the journal Science….

2018-07-11. Tiny Algae May Have Prompted a Mass Extinction. By Katherine Kornei, Eos/AGU. Excerpt: More than three quarters of all marine life died about half a billion years ago. …Below a certain depth in the stratigraphic record, trilobites, corals, and brachiopods thrived in the ocean. Above it, many types of these organisms are missing. What could have caused 85% of marine species—at a time when life largely existed only in the oceans—to just up and perish? New research offers an unlikely linchpin in this vast die-off: tiny algae. Around the time of this extinction event, algae populations were rising ocean-wide. When these abundant organisms lived, they soaked up atmospheric carbon and stored it in their tissues. But when they died, they may have sunk quickly through the water column, scientists have proposed, rapidly sequestering carbon in the depths of the ocean…. The new study “reveals how algal evolution could have been vital in regulating the Earth’s carbon cycle.” The planet then cooled as a result of having less carbon dioxide in the atmosphere, plausibly triggering the widespread glaciation that’s believed to have prompted one of the Earth’s largest mass extinction events, the new work suggests. …The new study “reveals how algal evolution could have been vital in regulating the Earth’s carbon cycle,” …. …The key to this hypothesis lies in ancient ocean sediments unearthed from Nevada dating to the very end of the Ordovician period, roughly 444 million years ago. Jiaheng Shen, lead author of the paper and a geochemist at Harvard University, and her colleagues collected samples of these sediments—mostly shale and limestone—and found that they contained compounds derived from chlorophyll…created by ancient algae, which died and sank to the seafloor to create the sediments. …samples from younger rocks…appeared to contain more and more material from algae. Over a period of just a few million years, the amount of the telltale compounds increased by approximately fivefold, the team estimated….

2018-06-07. Ancient Earth froze over in a geologic instant. By Lucas Joel, Science Magazine. Excerpt: Earth’s ice is melting at a rapid clip today. But some scientists think that during several ancient episodes, the planet plunged into a deep freeze known as “Snowball Earth,” when ice sheets grew to cover almost the entire planet. However, the number of these episodes, their extent, and just how fast Earth turned into an ice cube have long been a mystery. Now, analysis of a newly discovered rock sequence in Ethiopia supports a Snowball Earth event some 717 million years ago and suggests it took place in mere thousands of years—the geologic equivalent of a cold snap. The new work, grounded in Earth’s rock record, means the Snowball Earth hypothesis is “hanging in there, big time,” says Carol Dehler, a geologist at Utah State University in Logan, who was not involved in the research. …Maclennan and colleagues ventured to the small town of Samre, Ethiopia, where they came across a type of rock—which they later dated to roughly 717 million years old—that could have only formed through glacial activity. These rocks, called diamictites, are made of huge boulders transported great distances by glaciers. Buried just below those glacial rocks were older layers of carbonate rocks. As the ancient supercontinent Rodinia was breaking apart, these rocks formed in shallow waters with the aid of microbial marine organisms—a sign that the same location was warm just a bit earlier in time, Maclennan explains. Together, these layers suggest the ancient climate quickly shifted from tropical paradise to frozen wasteland, Maclennan and colleagues report this month in Geology….

2017-05-30. A Volcanic Trigger for Earth’s First Mass Extinction? By Lucas Joel, Earth & Space Science News (EoS, AGU). Excerpt: Abnormally high levels of mercury in Ordovician rocks may imply that a huge surge of volcanism took place at a time when much of the planet’s ocean life vanished. …Five major mass extinctions punctuate the history of life on Earth. The first is the Late Ordovician mass extinction, which began about 445 million years ago, triggered by a severe ice age and subsequent global warming that exterminated more than 85% of all marine species. Why the ice age that sparked the event was so drastic, however, is not clear. Recent research has suggested that large-scale volcanism before and during the extinction may be to blame, but evidence for volcanism has remained scant—until now. In a new study, researchers report the discovery of rock layers formed about the time of the extinction that are rich in the chemical element mercury, which they say is a telltale sign of volcanic activity….

2016-10-10. Simulating the Climate 145 Million Years Ago. By Shannon Hall, Earth and Space Science News (EoS, AGU). Excerpt: A new model shows that the Intertropical Convergence Zone wasn’t always a single band around the equator, which had drastic effects on climate. The United Kingdom was once a lush oasis. That can be read from sediments within the Kimmeridge Clay Formation, which were deposited around 160 to 145 million years ago on Dorset’s “Jurassic Coast.” …the formation is rich in organic matter, which suggests that it likely formed when global greenhouse conditions were at least 4 times higher than present levels. …Armstrong et al. used those black shales to build new climate simulations that better approximate the climate toward the end of the Jurassic period. The model simulated 1422 years of time that suggested a radically different Intertropical Convergence Zone—the region where the Northern and Southern Hemisphere trade winds meet—than the one today. The convergence of these trade winds produces a global belt of clouds near the equator and is responsible for most of the precipitation on Earth. …Today the Intertropical Convergence Zone in the Atlantic strays, at most, 12° away from the equator. However, 145 million years ago, when the continents were still much closer together, the model showed that the zone split, like a fork in the road, where the Pacific Ocean met the western coast of the American continents. The zone was driven apart by the proto-Appalachian mountain range to the north and the North African mountains to the south. …

2015-01-15. Tiny plant fossils offer window into Earth’s landscape millions of years ago. NSF Press Release 15-003. Excerpt: Minuscule, fossilized pieces of plants tell a detailed story of what Earth looked like 50 million years ago. Researchers have discovered a way of determining density of trees, shrubs and bushes in locations over time–based on clues in the cells of plant fossils preserved in rocks and soil. Tree density directly affects precipitation, erosion, animal behavior and a host of other factors in the natural world. Quantifying vegetation structure throughout time could shed light on how Earth’s ecosystems have changed over millions of years. …”The new methodology provides a high-resolution lens for viewing the structure of ecosystems over the deep history of our planet,” says Alan Tessier, acting director of the National Science Foundation’s (NSF) Division of Environmental Biology, which funded the research along with NSF’s Division of Earth Sciences. “This capability will advance the field of paleoecology and greatly improve our understanding of how future climate change will reshape ecosystems.” …”Using this method, we can finally quantify in detail how Earth’s plant and animal communities have responded to climate change over millions of years, vital for forecasting how ecosystems will change under predicted future climate scenarios.”….

2014-02-20. Seeking a Break in a 252 Million-Year-Old Mass Killing. A Geologist Investigates a Mass Extinction at the End of the Permian Period.   Excerpt: Sam Bowring … a geologist at M.I.T. … wants to understand how an estimated 96 percent of all species on Earth became extinct at the end of the Permian Period 252 million years ago…the biggest of the five mass extinctions recorded in the fossil record. …Dr. Bowring and his colleagues have … made the most precise measurement yet of how long it took for all those species to become extinct…less than about 60,000 years. That’s a geological blink of an eye — a fact that will help scientists evaluate different hypotheses for what triggered the mass extinction. …Studies on the rocks that formed around the time of the mass extinction … revealed that …Huge volcanoes in Siberia belched molten rock that covered millions of square miles. The oceans warmed dramatically, climbing 18 degrees Fahrenheit. …the carbon in the rocks that formed around the time of the mass extinction…have a drastically higher ratio of light-to-heavy carbon. One way to create such a planet-wide shift would be to deliver a huge surge of carbon dioxide into the ocean. …The volcanoes may well be the cause, but scientists have yet to establish all the links from eruptions to extinctions. …the Siberian eruptions lasted for one to two million years. But the world’s biodiversity did not decline over a similar time scale. Instead, it swiftly collapsed with little advance warning…. Carl Zimmer, The New York Times.

2013-10-08. When CO2 Levels Doubled 55 Million Years Ago, Earth May Have Warmed 9°F In 13 Years.  Excerpt: The Paleocene/Eocene thermal maximum (PETM) and associated carbon pulse “are often touted as the best geologic analog for the current” manmade rise in CO2 levels, as a new study notes. The Proceedings of the National Academy of Sciences paper, “Evidence for a rapid release of carbon at the Paleocene-Eocene thermal maximum,”  …Rutgers geologists Morgan Schaller and James Wright argue that: … following a doubling in carbon dioxide levels, the surface of the ocean turned acidic over a period of weeks or months and global temperatures rose by 5 degrees centigrade – all in the space of about 13 years. Scientists previously thought this process happened over 10,000 years. …Note that if we stay anywhere near our current emissions path, we are headed for a tripling or quadrupling of CO2 concentrations from preindustrial levels. …the “dean of climate scientists,” Wallace Broecker who popularized the term “global warming” …decades ago… said, “The climate system is an angry beast, and we are poking at it with sticks.” …“My point [with the ‘angry beast’ metaphor] was that by adding large amounts of CO2 to the atmosphere, we were poking our climate system without being sure how it would respond,” he says. At the rate we are spewing carbon pollution into the atmosphere, one might even say we are punching the climate beast in the nose. Paleoclimate studies, including this new one, suggests that is a very, very bad move…. Joe Romm, ThinkProgress. 

2012-12-09. 5 million-year hangover | By  Spencer Hunt, The Columbus Dispatch. Excerpt:  Scientists say climate change slowed recovery after the world’s greatest extinction event 250 million years ago. …250 million years ago during a time that scientists call the Great Dying … world’s greatest extinction event wiped out 90 percent of life in the oceans and about 70 percent on land. Earth did recover, but it took about 5 million years, according to a team of earth scientists, including Ohio State University geologist Matthew Saltzman. “That’s a relatively long amount of time,” he said. “We see mass extinctions throughout Earth’s history and, in most cases, the recovery took place in about 1 million years or so.” …the mass extinction was triggered by a series of severe volcanic eruptions in a region called the Siberian Traps. After 1 million years of heavy volcanic activity, an area larger than Europe was covered in a layer of once-molten igneous rock 1 mile to 3 miles thick…. Researchers theorize that magma from the initial eruptions burned through an ancient coal bed. …Thomas Algeo, a University of Cincinnati geologist, said huge amounts of carbon dioxide and methane were released, killing off most remaining species.  …After the Great Dying, increases in global temperatures made life nearly impossible for plants and animals on land and heated the oceans to an average 100 degrees Fahrenheit. …Saltzman said the Great Dying offers a window on the effects of climate change. He and Algeo cautioned that the current predictions for climate change are far from the global catastrophe that occurred 250 million years ago. …the average temperature increase then was two to three times higher than the increase climatologists are forecasting. Still, Saltzman said reactions to climate change can be severe…. Read the full article:

2012-09-10. Earlier Mass Extinction for Most of Marine Life | by Sindya Bhanoo, New York Times.  Excerpt:  Most scientists agree that dinosaurs became extinct as a result of a catastrophic meteor strike 65 million years ago near the Yucatán Peninsula. …But now scientists are suggesting that another mass extinction event occurred about 200,000 years earlier: a volcanic eruption on the Deccan Plateau of India. The eruption filled the atmosphere with aerosols — fine particles suspended in greenhouse gases that led to warming and, eventually, the extinction of much of marine life, especially shelled invertebrates on the ocean floor….. Read the full article:

2010 April 9.  Scientists Explore Origins of ‘Supervolcanoes’ on the Sea Floor. National Science Foundation Update. Excerpt: “Supervolcanoes” have been blamed for multiple mass extinctions in Earth’s history, but the cause of their massive eruptions is unknown. …”‘Supervolcanoes’ emitted large amounts of gases and particles into the atmosphere, and re-paved the ocean floor,” says Rodey Batiza, marine geosciences section head in the National Science Foundation (NSF)’s Division of Ocean Sciences, which co-funded the research. The result? “Loss of species, increased greenhouse gases in the atmosphere, and changes in ocean circulation,” says Batiza. In fall 2009, an international team of scientists participating in IODP Expedition 324 drilled five sites in the ocean floor. They studied the origin of the 145 million-year-old Shatsky Rise volcanic mountain chain… 1,500 kilometers (930 miles) east of Japan, … roughly the size of California… one of the largest supervolcanoes in the world: the top of Shatsky Rise lies three and a half kilometers (about two miles) below the sea’s surface, while its base plunges to nearly six kilometers (four miles) beneath the surface. … composed of layers of hardened lava, with individual lava flows that are up to 23 meters (75 feet) thick.
…About a dozen supervolcanoes exist on Earth; some are on land, while others lie at the bottom of the ocean. Those found on the seafloor are often referred to as large oceanic plateaus. Current scientific thinking suggests that these supervolcanoes were caused by eruptions over a period of a few million years or less–a rapid pace in geologic time.
…Shatsky Rise … is … the only supervolcano to have formed during a time when Earth’s magnetic field reversed frequently.” This process creates “magnetic stripe” patterns in the seafloor. “We can use these magnetic stripes to decipher the timing of the eruption,” says Sager”….

2010 March 4. NSF Release 10-037: Scientists Find Signs of “Snowball Earth” Amidst Early Animal Evolution. Excerpt: Geologists have found evidence that sea ice extended to the equator 716.5 million years ago, bringing new precision to a “snowball Earth” event long suspected to have taken place around that time.
…The new findings–based on an analysis of ancient tropical rocks that are now found in remote northwestern Canada–bolster the theory that our planet has, at times in the past, been ice-covered at all latitudes.
“This is the first time that the Sturtian glaciation has been shown to have occurred at tropical latitudes, providing direct evidence that this particular glaciation was a ‘snowball Earth’ event,” says lead author Francis Macdonald, a geologist at Harvard University.
…According to Enriqueta Barrera, program director in NSF’s Division of Earth Sciences, which supported the research, the Sturtian glaciation, along with the Marinoan glaciation right after it, are the greatest ice ages known to have taken place on Earth. “Ice may have covered the entire planet then,” says Barrera, “turning it into a ‘snowball Earth.'”
The survival of eukaryotes–life forms other than microbes such as bacteria–throughout this period suggests that sunlight and surface water remained available somewhere on Earth’s surface. The earliest animals arose at roughly the same time.
…”The fossil record suggests that all of the major eukaryotic groups, with the possible exception of animals, existed before the Sturtian glaciation,” Macdonald says. “The questions that arise from this are: If a snowball Earth existed, how did these eukaryotes survive? Did the Sturtian snowball Earth stimulate evolution and the origin of animals?”…

2009 June 21. Carbon Dioxide Higher Today Than Last 2.1 Million Years. ScienceDaily. Excerpt: Researchers have reconstructed atmospheric carbon dioxide levels over the past 2.1 million years in the sharpest detail yet, shedding new light on its role in the earth’s cycles of cooling and warming.
The study…is the latest to rule out a drop in CO2 as the cause for earth’s ice ages growing longer and more intense some 850,000 years ago. But it also confirms many researchers’ suspicion that higher carbon dioxide levels coincided with warmer intervals during the study period.
The authors show that peak CO2 levels over the last 2.1 million years averaged only 280 parts per million; but today, CO2 is at 385 parts per million, or 38% higher. This finding means that researchers will need to look back further in time for an analog to modern day climate change.
In the study, Bärbel Hönisch, a geochemist at Lamont-Doherty Earth Observatory, and her colleagues reconstructed CO2 levels by analyzing the shells of single-celled plankton buried under the Atlantic Ocean, off the coast of Africa. By dating the shells and measuring their ratio of boron isotopes, they were able to estimate how much CO2 was in the air when the plankton were alive. This method allowed them to see further back than the precision records preserved in cores of polar ice, which go back only 800,000 years.
…The low carbon dioxide levels outlined by the study through the last 2.1 million years make modern day levels, caused by industrialization, seem even more anomalous, says Richard Alley, a glaciologist at Pennsylvania State University, who was not involved in the research.
“We know from looking at much older climate records that large and rapid increase in CO2 in the past, (about 55 million years ago) caused large extinction in bottom-dwelling ocean creatures, and dissolved a lot of shells as the ocean became acidic,” he said. “We’re heading in that direction now.”…

14 November 2006. Paleoclimatology: Understanding the Past to Predict the Future. By Holli Riebeek. Scientists use complicated climate models to predict how Earth’s climate might change in the future. One of the best ways to test the reliability of such models is to see how well they recreate climates of the past.

7 November 2006 In Ancient Fossils, Seeds of a New Debate on Warming. By WILLIAM J. BROAD. NY Times. Excerpt: In recent years, scientists have learned about the changing makeup of the vanished gases by teasing subtle clues from fossilized soils, plants and sea creatures. They have also gained information from computer models that predict how phenomena like eroding rocks and erupting volcanoes have altered the planet’s evolving air. “It’s getting a lot more attention,” Michael C. MacCracken, chief scientist of the Climate Institute, a research group in Washington, said of the growing field. For the first time, the Intergovernmental Panel on Climate Change, a United Nations group that analyzes global warming, plans to include a chapter on the reconstructions in its latest report, due early next year.The discoveries have stirred a little-known dispute that, if resolved, could have major implications. One side foresees a looming crisis of planetary heating; the other, temperature increases that would be more nuisance than catastrophe. Some argue that CO2 fluctuations over the Phanerozoic follow climate trends fairly well, supporting a causal relationship between high gas levels and high temperatures. Other experts say that the fluctuations in the gas levels often fall out of step with the planet’s hot and cold cycles, undermining the claimed supremacy of carbon dioxide. Highlighting the gap, the two sides clash on how much the Earth would warm today if carbon dioxide concentrations double from preindustrial levels, as scientists expect. Many climatologists see an increase of as much as 8 degrees Fahrenheit. Carbon dioxide skeptics and others see the reconstructions of the last 15 years as increasingly reliable, posing fundamental questions about the claimed powers of carbon dioxide. “Some of the work has been quite meticulous,” Thure E. Cerling, an expert at the University of Utah on Phanerozoic climates, said. “We are likely to learn something.”

27 December 2005. Past Hot Times Hold Few Reasons to Relax About New Warming. By ANDREW C. REVKIN. Excerpt: Earth scientists with the longest frames of reference…often seem to be the least agitated about human-caused global warming … these backward-looking experts have seen it all before. … 49 million years ago the balmy Arctic Ocean, instead of being covered in ice, was matted with a cousin of the duckweed that cloaks suburban frog ponds. The forests on the continent now called Antarctica and on shores fringing the Arctic were once thick and lush. And through hundreds of millions of years, concentrations of carbon dioxide and the other trace gases that trap solar energy and prevent the planet from being an ice ball have mostly been far higher than those typical during humankind’s short existence. … A hot, steamy earth would be fine for most forms of life. …Studies of the past also show that pace matters. The rise in temperature and greenhouse gases during the great heat wave 55 million years ago, while instantaneous on a geological time scale, took thousands of years to unfold. But the pace of the recent rise in carbon dioxide is as much as 200 times as fast as what has been estimated in past rapid climate transitions. 

May 2005. Weathering Climate Variability. ScienceMatters@Berkeley. When it comes to weather, most of us are only concerned with the forecast. UC Berkeley professor Lynn Ingram is more interested in old news. Very old. She studies how California’s climate has changed over thousands of years. Her research could help prepare us for what tomorrow’s weather may bring

Life and Climate book cover

Non-chronological resources

Historical Isotopic Temperature Record from the Vostok Ice Core

CLIMATE TIME LINE INFORMATION TOOL. The Climate Time Line Information Tool (CTL) is being developed and evaluated by science educators at the University of Colorado and NOAA as a tool for exploring the complex world of climate science and history. The developers ultimately see the prototype supporting science concepts such as systems, cycles, energy transfer, patterns and scale, and science as inquiry. The site’s basic design is an interactive matrix that uses the “powers of ten” approach to frame 1) climatic processes and 2) specific climate events of the past at varying time scales. Each time scale has its own list of sources and links to more information. The web site is a work in progress and the developers would like feedback from science educators and students. Audience: college level instruction.