Taxonomy term

paleoclimate

Mediterranean tsunami record may be overreported

Tsunamis are one of the most destructive natural hazards on Earth, sometimes even upstaging the major earthquakes that send the waves surging across entire ocean basins. Knowing when, where and how severely tsunamis have struck coastlines in the past is valuable for countries trying to prepare for the impacts of future tsunamis. But distinguishing tsunami deposits in geologic paleorecords from deposits left by more common storm waves is notoriously difficult. Researchers recently highlighted this challenge by taking a hard look at tsunami- and storm-wave records around the Mediterranean Sea over the last 4,500 years. The findings may serve as a cautionary tale for scientists interpreting tsunami records elsewhere in the world.

18 Jan 2018

Volcanism spiked global temps during past hothouse

Roughly 56 million years ago, global temperatures rose 5 degrees Celsius within a few thousand years in an event called the Paleocene-Eocene Thermal Maximum (PETM). Scientists have often attributed the relatively rapid warming of the PETM — frequently used as an analogue for understanding modern warming trends — to large-scale biogenic methane emissions from seafloor reservoirs. But in a new study, researchers tracking carbon and boron isotopes preserved in the shells of tiny marine creatures called foraminifera, or forams, question the conventional wisdom, instead pointing to a volcanic source for the carbon emitted during the PETM.

25 Dec 2017

Mangroves sprouted in Arctic during Eocene

Mangrove trees, which today thrive in tropical and subtropical climates in the low and midlatitudes, grew in the high Russian Arctic about 56 million years ago, scientists reported in Geology. It’s the northernmost occurrence of mangrove trees ever documented.

24 Oct 2017

Reconstructing ancient oxidant levels and their climatic effects

Oxidants in the troposphere, such as ozone and hydroxyl radicals, influence the life spans of other atmospheric components, including pollutants and greenhouse gases like carbon monoxide and methane. But how the abundance of tropospheric oxidants varies as climate changes is poorly understood. Part of the challenge is that these oxidants are too reactive to be preserved in paleo-records, such as ice cores.

29 Aug 2017

Transylvanian ice cave reveals European winter climate record

Over the last 10,000 years, water dripping into a cave in Transylvania has frozen into one of the largest and oldest cave glaciers in the world. Today, the Scărișoara Ice Cave in central Romania preserves one of the longest ice records on Earth, a boon for climate researchers seeking to study how Europe’s climate has fluctuated during the Holocene.

23 Aug 2017

Down to Earth With: Paleoclimatologist Gifford H. Miller

“Hope for the unexpected.” This motto has pulled paleoclimatologist Gifford H. Miller to remote corners of the world to conduct fieldwork for more than half a century. Miller, a professor of geological sciences at the University of Colorado Boulder (CU) and associate director of the Institute for Arctic and Alpine Research, thrives on the pursuit of knowledge, asking tough questions about the global climate system whose answers have far-reaching implications. But it’s the thrill of unexpected discoveries — of which he’s made many — that keep him returning for more. His discoveries, including the extinction timing of giant birds in Australia, the existence of “zombie mosses” that document the life-cycle of Arctic ice caps, and the finding of lake sediments that tell the story of Iceland’s deglaciation, have led to advances in our understanding of Earth’s climate history and the role humans have played in it.

30 Jun 2017

Sea-surface temperatures during last interglacial similar to modern day

During the last interglacial period, between 129,000 and 116,000 years ago, global sea levels were 6 to 9 meters higher than at present. Scientists have long wondered how global atmospheric and ocean temperatures then compared to modern times, but efforts to reconstruct such temperatures have often fallen short. In a new study, researchers who compiled past records of sea-surface temperatures (SSTs) have revealed that SSTs during the last interglacial were similar to modern day temperatures. But, the similarity doesn’t necessarily predict a future surge in sea levels.

10 May 2017

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

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