The team scoured the Annals and other sources for reliable reports of particularly cold climate, including major snowfalls, periods of prolonged frost or ice on lakes and rivers, and general observations of abnormally cold weather. During the 1200-plus-year period of interest, the team identified 70 such cold spells. It's clear that the scribes were diligent reporters of such episodes, most probably because of the negative impacts that cold weather had on livestock, crops, and society in general, Ludlow says.
Then, the researchers scrutinized the Greenland ice core for evidence of volcanic eruptions, as denoted by ice layers particularly rich in sulfates. During the same 12-century interval, they identified 48 distinct eruptions—many of which likely occurred at high latitudes in the Northern Hemisphere— including Iceland, which lies nearby and upwind of Ireland—but some that may have occurred in the tropics. One of the eruptions, probably the largest of the period, occurred in 1600 in what is now Peru, Ludlow says.
Thirty-eight of the 48 eruptions occurred within 5 years of 37 of the episodes of cold weather, the researchers report online this week in Environmental Research Letters. Five years may seem a long time between volcanic cause and climatic effect, Ludlow says. But the inaccuracy of the ice core's sulfate record (plus-or-minus about 2 years), as well as any time lag between the active phase of an eruption and the time when sulfates actually were deposited, make it difficult to assess any volcano/climate link across a tighter time window.
African climate is generally considered to have evolved towards progressively drier conditions over the past few million years, with increased variability as glacial–interglacial change intensified worldwide.
Palaeoclimate records derived mainly from northern Africa exhibit a 100,000-year (eccentricity) cycle overprinted on a pronounced 20,000-year (precession) beat, driven by orbital forcing of summer insolation, global ice volume and long-lived atmospheric greenhouse gases4.
Here we present a 1.3-million-year-long climate history from the Lake Malawi basin (10°–14° S in eastern Africa), which displays strong 100,000-year (eccentricity) cycles of temperature and rainfall following the Mid-Pleistocene Transition around 900,000 years ago.
Interglacial periods were relatively warm and moist, while ice ages were cool and dry. The Malawi record shows limited evidence for precessional variability, which we attribute to the opposing effects of austral summer insolation and the temporal/spatial pattern of sea surface temperature in the Indian Ocean.
The temperature history of the Malawi basin, at least for the past 500,000 years, strongly resembles past changes in atmospheric carbon dioxide and terrigenous dust flux in the tropical Pacific Ocean, but not in global ice volume. Climate in this sector of eastern Africa (unlike northern Africa) evolved from a predominantly arid environment with high-frequency variability to generally wetter conditions with more prolonged wet and dry intervals.
The Transantarctic Mountains are the most remote mountain belt on Earth, an utterly pristine wilderness of ice and rock rising to majestic heights and extending for 1,500 miles. In this book, Edmund Stump is the first to show us this continental-scale mountain system in all its stunning beauty and desolation, and the first to provide a comprehensive, fully illustrated history of the region's discovery and exploration.
The author not only has conducted extensive research in the Transantarctic Mountains during his forty-year career as a geologist but has also systematically photographed the entire region. Selecting the best of the best of his more than 8,000 photographs, he presents nothing less than the first atlas of these mountains. In addition, he examines the original firsthand accounts of the heroic Antarctic explorations of James Clark Ross (who discovered the mountain range in the early 1840s), Robert Falcon Scott, Ernest Shackleton, Roald Amundsen, Richard Byrd, and scientists participating in the International Geophysical Year (1957–1958). From these records, Stump is now able to trace the actual routes of the early explorers with unprecedented accuracy. With maps old and new, stunning photographs never before published, and tales of intrepid explorers, this book takes the armchair traveler on an expedition to the Antarctic wilderness that few have ever seen.
“An Empire of Ice reflects exhaustive digging and reaches well beyond the standard source materials. . . . Larson provides enough fresh perspective that even devotees of polar literature will learn things.”—Jennifer Kingson, New York Times Book Review (Jennifer Kingson New York Times Book Review)
Awarded an Honorable Mention in the 2011 National Outdoor Book Awards (National Outdoor Book Award Honorable Mention National Outdoor Book Foundation)
“A far more interesting and richer account than we have had thus far. . . . Larson has written a fascinating book, one sure to force a rethinking of the Scott-Amundsen race as well as reconsiderations that will include science as a driving force in Antarctic and indeed polar exploration.” —Vassiliki Betty Smocovitis, Science Magazine (Vassiliki Betty Smocovitis Science Magazine)
"The author provides an undeniably exciting account without overpowering the reader with too much detail. Fans of these explorers, science heads, and armchair travelers will find this a worthwhile and thrilling read."—Mike Rogers, Library Journal (Mike Rogers Library Journal)
“Pulitzer Prize–winning historian Larson sheds new light on the famous three-way race to the South Pole….A satisfying tale of adventure and exploration.”—Kirkus Reviews
"...Fortunately, because the Sun is much brighter than the typical star, the one planet with a pleasant climate – Earth – lies so far away that it spins freely, so most latitudes enjoy a short (24-hour) cycle of day and night. However, solar tides have dramatically slowed the spins of Mercury and Venus. Mercury spins once every 58.65 days – exactly two-thirds of its 88-day-long year. As a result, the day is so hot that it could melt lead and the night is colder than on Saturn.
Solar tides have also slowed the spin of Venus, which revolves around the Sun every 225 days and rotates every 243 days. The slight mismatch arises, scientists believe, because winds in its thick atmosphere, whose surface pressure is 93 times the that of the Earth, rub against the planet's surface and alter its spin.
Leconte and his colleagues wondered what would happen if a planet with a thinner atmosphere, like that of the Earth, revolved close to an orange- or red-dwarf star. To their surprise, the calculations indicate that, in many cases, such a world can still rotate freely. For example, a planet orbiting a red-dwarf star that is 60% as massive as the Sun does not suffer tidal locking, even if it is only a third as far from the star as Earth is from the Sun. That distance puts the planet in the red-dwarf's habitable zone, where temperatures are pleasant and liquid water can exist. And if the planet's atmosphere is 10 times thicker than that of the Earth, the planet can be even closer and still rotate freely.
Locked yet lively
What are the implications for habitability? "It's a tricky question," Leconte says. On the one hand, the climate of a freely spinning planet can mimic Earth's. On the other hand, the day side of a tidally locked planet could also support life, because previous studies have found that an atmosphere can ferry heat to the night side, so that the air does not freeze and disappear...."
At 5:36 p.m. on March 27, 1964, a magnitude 9.2. earthquake – the second most powerful in world history – struck the young state of Alaska. The violent shaking, followed by massive tsunamis, devastated the southern half of the state and killed more than 130 people. A day later, George Plafker, a geologist with the U.S. Geological Survey, arrived to investigate. His fascinating scientific detective work in the months that followed helped confirm the then-controversial theory of plate tectonics.
In a compelling tale about the almost unimaginable brute force of nature, New York Times science journalist Henry Fountain combines history and science to bring the quake and its aftermath to life in vivid detail. With deep, on-the-ground reporting from Alaska, often in the company of George Plafker, Fountain shows how the earthquake left its mark on the land and its people -- and on science.
5 years ago: The Ragged Edge of the World: Encounters at the Frontier Where Modernity, Wildlands and Indigenous Peoples Meet by Eugene Linden.
"A pioneering work of environmental journalism that vividly depicts the people, animals and landscapes on the front lines of change's inexorable march.
A species nearing extinction, a tribe losing centuries of knowledge, a tract of forest facing the first incursion of humans-how can we even begin to assess the cost of losing so much of our natural and cultural legacy?
For forty years, environmental journalist and author Eugene Linden has traveled to the very sites where tradition, wildlands and the various forces of modernity collide. In The Ragged Edge of the World, he takes us from pygmy forests to the Antarctic to the world's most pristine rainforest in the Congo to tell the story of the harm taking place-and the successful preservation efforts-in the world's last wild places.
The Ragged Edge of the World is a critical favorite, and was an editors' pick on Oprah.com."
Ten Thousand Years from Tomorrow. Francois Sarrazin, Sorbonne Universités, UPMC Univ Paris 06, Muséum National d'Histoire Naturelle
Evolution in the Anthropocene Science 26 Feb 2016: Vol. 351, Issue 6276, pp. 922-923
“Most current conservation strategies focus on the immediate social, cultural, and economic values of ecological diversity, functions, and services (1). For example, the Intergovernmental Platform on Biodiversity and Ecosystem Services (2) mostly addresses the utilitarian management of biodiversity from local to global scales. However, besides urgent diagnosis and actions (3, 4), processes that occur over evolutionary time scales are equally important for biodiversity conservation. Strategizing for conservation of nature at such long time scales will help to preserve the function—and associated services—of the natural world, as well as providing opportunities for it to evolve. This approach will foster a long-term, sustainable interaction that promotes both the persistence of nature and the wellbeing of humans.
“Considering the evolutionary trajectories of nonhumans beyond human interest may also constitute a major evolutionary transition (5). It would be the first case in the history of life on Earth where a species cares for the evolution of other species beyond its own fitness and well-being.
“We must understand why the universe began in an incredibly special state, so well ordered that 14 billion years later, the universe still has not reached maximum disorder. Penrose is at his best when he explains this deep and beautiful mystery, and the book may be worth reading for this chapter alone.” —Science
Proto-Solar System's Magnetic Field. Ken Croswell, @sciencemagazine.
"Earth and its planetary neighbors arose in a magnetic field strong enough to sculpt the disk of gas and dust that spawned our solar system and set the stage for a planet capable of developing life. That's the implication of new work that uses a meteorite to deduce the strength of the magnetic field around the young sun.
"Planets arise in so-called protoplanetary disks, which orbit young stars but disperse after a few million years as material from the disk both falls into the star and gets pushed away. What causes this transfer of mass? Some researchers suspect magnetic forces do the job, but no one has ever measured a protoplanetary disk's magnetic intensity....
"Was the ancient magnetic field just the right strength to mold the sun's protoplanetary disk into a solar system containing a world of the right size at the right orbital distance to develop life? "I don't think we understand the processes well enough to really make that connection directly," Wilner says, "but it surely wouldn't surprise me if there were differences" in the properties of the sun's planets had the magnetic field been stronger or weaker."...
Ten thousand years ago, giant ice islands in America. @sidperkins @sciencemagazine
“…As the last ice age waned and climate warmed, immense lakes of glacial meltwater that accumulated behind natural ice dams occasionally burst forth from the mouth of Canada’s Hudson Bay and the Gulf of St. Lawrence. When those iceberg-laden outburst floods—some of them carrying more than 1 million cubic meters of water per second and lasting several months—reached the open sea, they took a right turn and flowed south along the coast as far as the Florida Keys, a new study suggests. The torrent-driven icebergs, some of them hundreds of meters thick, plowed troughs in the sea floor all along the continental shelf (like those found in 170- to 380-meter-deep waters off the coast of South Carolina; one such berm-edged trough extends from lower left to top center of the image). Sea levels have risen more than 100 meters since most of these troughs were formed, which has helped preserve them from surface waves that could roil and smooth seafloor sediments.
Unknown comets at the edge of the system. Bob Zimmerman, BehindtheBlack.com
Using data from the WISE space telescope, astronomers have found that there are more comets lurking in the far reaches of the solar system than they had predicted.
Scientists found that there are about seven times more long-period comets measuring at least 0.6 miles (1 kilometer) across than had been predicted previously. They also found that long-period comets are on average up to twice as large as “Jupiter family comets,” whose orbits are shaped by Jupiter’s gravity and have periods of less than 20 years. Researchers also observed that in eight months, three to five times as many long-period comets passed by the Sun than had been predicted.
These are comets whose orbits never allow them to come close to the inner solar system, which allows them to remain puffy and large.
Wind is an ever-present force. From a gentle breeze to a cold arctic blast, it is constantly shaping the landscape and the weather. But where does wind come from.
Simply put, wind is the motion of the air around us, generated by differences in pressure in the Earth's atmosphere. Air is a fluid, and just like water, it obeys the laws of fluid dynamics. It will seek to flow from a region of higher pressure to one of lower pressure, says Chris Maier, a meteorologist with the National Oceanic and Atmospheric Administration’s National Weather Service.
Earth's air-filled atmosphere is constantly but unevenly pressurized, with highs and lows at various places caused by the uneven heating of Earth’s surface by the sun. The air at the North or South Pole is colder and denser, while the air at the Equator is warmer and rises more easily. The colder, more highly pressurized polar air is constantly trying to move down to the Equator to replace the warm, rising air.
Read more: SMITHSONIAN
The very concept of the Anthropocene suggests that humans are actively shaping the planet in ways that will resonate through geologic time. But how has the planet—in this case, geography—shaped human societies since the days of our earliest ancestors.
In this week's episode of Generation Anthropocene, producer Mike Osborne talks with Ian Morris, a professor in the Stanford Archaeology Center and author of the 2010 book Why the West Rules—For Now. Morris developed a social development index to try to quantify the way societies and cultures have grown and changed with time. The index is based on four key factors: urbanization, information technology, war-making capacity and energy capture per capita, or how much food, water and other natural resources each person consumes.
Read more: SMITHSONIAN
Photo: Artist's conception of the surface of Proxima Centauri b. The Alpha Centauri binary system can be seen in the background, to the upper right of Proxima
ESO/M. Kornmesser - https://www.eso.org/public/images/eso1629a/
This artist’s impression shows a view of the surface of the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. The double star Alpha Centauri AB also appears in the image to the upper-right of Proxima itself. Proxima b is a little more massive than the Earth and orbits in the habitable zone around Proxima Centauri, where the temperature is suitable for liquid water to exist on its surface.)
The mystery of the origin of Proxima b. Ken Croswell @nature
“…The habitability of planets like Proxima b—in the sense of sustaining an atmosphere and liquid water on its surface—is a matter of intense debate. The most common arguments against habitability are tidal locking, strong stellar magnetic fields, strong flares and high ultraviolet and X-ray fluxes; but none of these have been proved definitive. Tidal locking does not preclude a stable atmosphere via global atmospheric circulation and heat redistribution21. The average global magnetic flux density of Proxima is 600 ± 150 G (ref. 22), which is quite large compared with that of the Sun (1 G). However, several studies have shown that planetary magnetic fields in tidally locked planets can be strong enough to prevent atmospheric erosion by stellar magnetic fields23 and flares24. Because of its close orbit to Proxima, Proxima b suffers from X-ray fluxes that are approximately 400 times that experienced by Earth, but studies of similar systems indicate that atmospheric losses can be relatively small25. Further characterization of such planets can also inform us about the origin and evolution of terrestrial planets. For example, the formation of Proxima b from in situ disk material is implausible because disk models for small stars would contain less than 1M⊕ of solids within a distance of 1 AU. There are three possibilities: the planet migrated in via type I migration26; planetary embryos migrated in and coalesced at the current planet’s orbit; or pebbles/small planetesimals migrated via aerodynamic drag27 and later coagulated into a larger body. Although migrated planets and embryos that originate beyond the ice-line would be rich in volatiles, pebble migration would produce much drier worlds. A warm terrestrial planet orbiting Proxima offers the opportunity to attempt further characterization via transits (ongoing searches), by direct imaging and high-resolution spectroscopy in the next decades28, and possibly robotic exploration in the coming centuries29…”
Curiosity rescued by engineering magicians. Bob Zimmerman, BehindtheBblack.com
Improved software uploaded to Curiosity to extend wheel life.
Engineers have designed and uploaded new software to Curiosity to better protect and use the rover’s wheels as it travels over rough terrain.
The software, referred to as traction control, adjusts the speed of Curiosity’s wheels depending on the rocks it’s climbing. After 18 months of testing at NASA’s Jet Propulsion Laboratory in Pasadena, California, the software was uploaded to the rover on Mars in March. Mars Science Laboratory’s mission management approved it for use on June 8, after extensive testing at JPL and multiple tests on Mars.
The timing is important, because Curiosity is about to move into terrain that looks far rougher than the ground it has so far traversed.