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Ice (Re)Cap: September 2018

From Antarctica to the Arctic; from polar caps, permafrost and glaciers to ocean-rafted sea ice; and from burly bears to cold-loving microbes, fascinating science is found in every nook and crevasse of Earth’s cryosphere, and new findings are announced often. 

07 Sep 2018

Ocean tide size linked to supercontinent cycle

Daily tides are driven primarily by Earth’s rotation and the gravitational force of the moon on oceans. However, in a new study in Geophysical Research Letters, researchers suggest that tidal magnitudes are also influenced, on longer timescales, by the size and shape of the ocean basins, and are therefore driven by plate tectonics.

07 Sep 2018

Obliquity and eccentricity determine exoplanet habitability

Finding habitable Earth-like planets may be even more challenging than previously thought, suggests a recent Astronomical Journal study looking at how the planetary obliquity, or tilt relative to an orbital axis, and orbital eccentricity affect the habitability of planets orbiting G-dwarf stars — which are similar to the sun.

05 Sep 2018

Readying the Caribbean for the next big wave

The Caribbean is famous for clear blue waters and serene white sand beaches, and infamous for destructive hurricanes — but another type of natural disaster can also strike: tsunamis.

03 Sep 2018

Ancient DNA reveals diversity of Southeast Asia

Southeast Asia is one of the most genetically and linguistically diverse regions on Earth. New sequencing of ancient human DNA is helping scientists piece together the puzzle of how repeated influxes of hunter-gatherers and farmers to the area over the last 50,000 years created the high level of diversity seen today.

03 Sep 2018

Mercury links Big Five extinction events

Mercury concentration spikes in the geologic record have been linked to massive volcanism in the form of large igneous provinces (LIP) such as the Deccan Traps, a kilometers-thick heap of basalt layers that formed in what is now India beginning late in the Cretaceous, and the Siberian Traps, an even larger mass of lava that erupted in Siberia at the end of the Per­mian. It’s thought that vast gas emissions associated with LIP eruptions could have significantly changed climate patterns and affected conditions such as ocean acidity. 

31 Aug 2018

An asteroid redirected bird evolution

When an asteroid hit Earth 66 million years ago, it helped wipe out all the dinosaur lineages save one: the birds. But birds didn’t completely dodge the cataclysm the asteroid triggered. Recent research suggests that forests around the planet were devastated. With forests gone, bird species that called trees home went extinct alongside their nonavian dinosaur cousins. This means that the birds that we see living in trees today evolved from lineages that, in the aftermath of the impact, were ground-dwelling.

30 Aug 2018

Sunstones useful as Viking-era GPS

The Vikings ruled the North Atlantic for hundreds of years without the benefits of magnetic compasses on the rough, often stormy waters. Legends have told of Vikings using sun compasses during clear weather and “sunstones” in cloudy conditions to navigate their weeks-long journeys between ports. A new study finds that sunstones made of calcite, cordierite or tourmaline may have indeed been accurate navigational tools.

28 Aug 2018

Gravity changes portended 2011 Tohoku earthquake

A new analysis of satellite data has revealed a distinct change in the gravity signal measured across the Japanese archipelago starting several months before the March 11, 2011, magnitude-9.1 Tohoku-Oki earthquake — one of the largest seismic events in recorded history.

27 Aug 2018

Grazing gave elephant ancestors an edge

The poor dental hygiene of some ancient elephant-like beasts has proven a boon to future scientists. In a new study, researchers used grass fragments recovered from the teeth of two extinct species of Central Asian gomphotheriids to decode the animals’ feeding habits during the middle Miocene.

24 Aug 2018

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