Taxonomy term

paleoclimate

Great drying led to great dying down under

If not for the megafaunal extinctions that wiped out many large animals at the end of the Pleistocene, the world might be a very different place today — with humans coexisting alongside still-living saber-toothed tigers, woolly mammoths and 3-meter-tall birds. The agents of these mass extinctions have been debated for decades: Were shifting climates, or our spear-wielding ancestors mainly responsible? A new study of the receding shorelines of Australia’s largest lake has found that a substantial drying of the environment, more so than human pressure, is mostly to blame for the loss of megafauna down under.
 
08 Jul 2015

Did volcanism drive Earth into global glaciation?

Between about 720 million and 635 million years ago, Earth suffered two big chills. During these “Snowball Earth” episodes, geologists think the world’s oceans froze over and glaciers spilled from tropical coastlines. Scientists have previously suggested that intense volcanism, unleashed by the disintegration of the supercontinent Rodinia, plunged Earth into these global glaciations. New research now lends support to this so-called fire-and-ice hypothesis.
05 Jun 2015

Old piles of shells reveal ancient El Niño patterns

Understanding of the El Niño-Southern Oscillation (ENSO) is evolving as scientists unearth new data sources. In a study recently published in Science, scientists turned to the discarded remains of shellfish for a 10,000-year record of eastern Pacific ENSO activity, which offered glimpses into unexpected past ENSO behavior and intensity.

03 Jan 2015

Ancient storms recorded in Yucatán cave

Today, one can find a plethora of records about coastal storms — everything from local news footage of wading meteorologists to the moment-to-moment wind speeds and barometric pressures of entire seasons of Atlantic hurricanes recorded in NOAA databases. Ancient storms are harder to track, unless they left a mark in the geologic record. Now, researchers have a new proxy record, one of the longest to date, to study ancient storms.

23 Dec 2014

Last Scottish glacier melted during big chill?

Scotland’s craggy peaks, deep lochs and fjord-lined coast are hallmarks of a landscape shaped by successive glaciations, the last of which, toward the end of the Pleistocene, draped the highlands with an ice cap covering 9,500 square kilometers. Rocky moraines give scientists a clear picture of the boundaries of this glaciation, called the Loch Lomond Advance, although the timeline of its growth and eventual demise has proved difficult to pin down.

18 Dec 2014

Pliocene tropical oceans were warmer after all

Scientists may have overturned the idea that Earth’s tropical oceans were the same temperature during the Early to Middle Pliocene — between about 5 million and 3 million years ago — as they are today, despite the world being a far warmer place then.

12 Dec 2014

Boron proxies detail past ocean acidification

Pockmarked plankton shells and dead coral are becoming the hallmark images of ocean acidification. But this isn’t the first time seawater has dropped on the pH scale. Based on models of seawater chemistry, the ocean acidity during the Paleocene-Eocene Thermal Maximum (PETM), beginning about 56 million years ago, is the closest-known analog to today. Now, researchers using boron proxies preserved in microfossils to reconstruct surface-ocean chemistry suggest that acidification was more extensive and lasted longer than previously thought, although the PETM conditions still don’t outpace the current rate of ocean acidification.

25 Sep 2014

Of char and carbon: The story of a buried soil

The so-called Brady soil — a dark horizon up to a meter thick that underlies much of Kansas and Nebraska — is widespread but often unseen. The layer is a paleosol, or fossil soil, that formed about 15,500 to 13,500 years ago when the region was a stable grassland built atop dunes of thick, wind-blown loess. That changed when the Laurentide Ice Sheet retreated and dunes swallowed the grasslands.

22 Sep 2014

New climate record challenges ideas about recent glaciations

Predicting how a changing climate and rising sea levels might impact humans in the future requires an understanding of how Earth has changed in the past. So scientists are continually seeking more and better data to help illuminate earlier conditions.
 

08 Sep 2014

Acid oceans followed Chicxulub impact

Within days after the massive Chicxulub impact that ended the Cretaceous Period 65.5 million years ago, a deluge of acid rain may have turned Earth’s ocean surfaces into suddenly inhospitable homes for a multitude of microorganisms, ultimately pushing them to extinction, according to a new study.
 

21 Aug 2014

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