Taxonomy term

paleoclimate

Down to Earth With: Cave scientist and paleoclimatologist Kathleen Johnson

Paleoclimatologist Kathleen Johnson has some advice for anyone interested in tropical cave science: befriend experienced cave guides and beware of venomous snakes, ubiquitous bats and Frisbee-sized spiders.

24 Feb 2017

Down to Earth With: Paleoclimatologist Raymond S. Bradley

When 21-year-old Raymond S. Bradley left England in 1969 to pursue a graduate degree at the University of Colorado Boulder (CU), he thought he’d be studying Denver’s urban climate. But on arrival, a funding mix-up delayed the work and Bradley found himself in search of a new project. While his doctoral work would ultimately involve studying the precipitation history of the Rockies, a new opportunity came his way in the summer of 1970 when his officemate needed a field assistant for a trip to the Arctic. So, Bradley headed to Baffin Island in the Canadian Arctic on a three-month excursion that would prove to be just the first of dozens of Arctic expeditions to come over the course of a distinguished career.

04 Jan 2017

Frosted forams foil radiocarbon dating

Climate studies often rely on radiocarbon dating of tiny shells in seafloor sediments to pinpoint the timing of when warming or cooling events began and ended. But a new study indicates that chemical reactions that take place on the seafloor may affect the accuracy of such radiocarbon dates, with potential implications for the dates published by past studies

01 Nov 2016

When Earth hit the reset button on life: New research on the Permian-Triassic mass extinction

The Permian-Triassic extinction 252 million years ago extinguished most life on Earth. Recent research weighs in on the kill mechanisms, the timing of the extinctions on land and in the water, and how the environmental degradation of the past may shed light on our current mass extinction.

25 Oct 2016

Bad weather hampered Mongol invasion of Europe

In 1241, the armies of the Mongol Empire, continuing their campaign through Asia and Europe, invaded western Hungary. Before long, however, the Mongols withdrew their forces, beating a sudden retreat that has long baffled historians. Now, drawing on high-resolution climate data from tree rings, researchers may have found a clue as to why: It seems wet weather created adverse conditions for the Mongol army, eventually forcing it to retreat from what was to become historically its westernmost advance.

 
25 Sep 2016

Growth rings in rocks reveal past climate

Paleoclimate studies often depend on mineral or sediment layers deposited seasonally or annually in caves, lakes and ice, but such records leave gaps where caves, lakes or ice sheets aren’t found. Now, scientists using a new technique that analyzes calcite layers ringing pebbles and rocks in arid landscapes are opening a new window onto the climate history of western North America. And because such deposits are found all over the world, the technique might prove to be a useful new tool for studying paleoclimate globally.

02 May 2016

Fossil leaves provide clues to ancient Australian habitat

Researchers have long thought that the scrublands of Australia developed over the last 25 million to 30 million years as part of a global trend toward colder and drier climates in which rainforests yielded ground to more open, fire-prone environments.

20 Apr 2016

Volcanic aerosols not enough to cause mass extinctions?

Mass extinctions — when more than half of Earth’s species disappear in a geologic instant — offer some of the planet’s most perplexing unsolved mysteries. Prolonged periods of volcanic activity have long been prime suspects for these ancient whodunits, the most recent of which finished off the last nonavian dinosaurs at the close of the Cretaceous about 66 million years ago. But scientists debate how drastic the environmental effects of such volcanism might have been, and whether other factors — like asteroid impacts, as in the end-Cretaceous extinction — played a big role as well.

25 Feb 2016

Southbound icebergs off the hook for ice-age cooling

During the Late Pleistocene, changes in North Atlantic Ocean circulation triggered abrupt changes in global climate: In some locations in the Northern Hemisphere, average temperatures dropped by as much as 10 degrees Celsius within a few decades. Scientists have long thought that freshwater from melting icebergs traveling south from the Arctic may have instigated the circulation shifts that contributed to cooling feedback loops. But now, scientists looking at seafloor sediments collected near Iceland have found that pulses of icebergs typically arrived after the onset of cooling episodes, too late to be primary drivers of climate change.
 
11 Aug 2015

Widening the window of human dispersal into Arabia

The vast sea of sand that is much of the Arabian Peninsula presents a formidable barrier to travel, even with today’s modern conveniences. How and when our ancestors crossed this dry expanse after leaving Africa — on their way to populating the rest of the world — has long been a mystery. Now, a new paleoclimate study paints a wetter picture of Arabia during the time of human expansion, and the findings may change scientists’ thinking about the route and timing of early human migrations out of Africa.

31 Jul 2015

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