Posts tagged national geographic

propaedeuticist:

hues of Uroplatus Phantasticus that mimic varying stages of leaf decay

(Source: propaedeuticist)

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Scientists at Los Alamos National Laboratory study nuclear explosions by using 3-D simulations. They follow a long tradition of nuclear research that led to the creation of the atomic and hydrogen bombs.
(via Nuclear Explosion Simulation Picture – Science Photo - National Geographic Photo of the Day)

Scientists at Los Alamos National Laboratory study nuclear explosions by using 3-D simulations. They follow a long tradition of nuclear research that led to the creation of the atomic and hydrogen bombs.

(via Nuclear Explosion Simulation Picture – Science Photo - National Geographic Photo of the Day)

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Harlequin shrimp underwater in the Lembeh Strait, Indonesia, on a piece of music nestled amid some garbage.

Harlequin shrimp underwater in the Lembeh Strait, Indonesia, on a piece of music nestled amid some garbage.

(via abluegirl)

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Glacier Caving
300 feet into the Greenland ice sheet, these glacier cavers rappel into mammoth caves which are formed when geothermal vents or meltwater cut into the ice. The Greenland ice sheet covers 80% of Greenland and would rise global sea levels 7.2m if it were to melt.
(Image via National Geographic)

Glacier Caving

300 feet into the Greenland ice sheet, these glacier cavers rappel into mammoth caves which are formed when geothermal vents or meltwater cut into the ice. The Greenland ice sheet covers 80% of Greenland and would rise global sea levels 7.2m if it were to melt.

(Image via National Geographic)

(via throughascientificlens)

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National Geographic: Expedition to Everest

  1. The sun sets over the west shoulder of Everest (right) and Nuptse, a neighboring peak.
  2. At dawn, a sliver of moon shines above the Western Cwm.
  3. At dawn, a Sherpa runs uphill across a ladder spanning a crevasse at the top of the Khumbu Icefall.
  4. Sherpas’ headlamps illuminate the Khumbu Icefall early in the morning. 
  5. Sherpas may pass through the Khumbu 30 or 40 times this season to carry up our food and tents.

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 Sundurbans Mangroves

Mangroves anchor the edges of the world, but they are slipping away, thanks to coastal development, pollution, over-harvesting, nutrient loading, overuse of freshwater, and climate change.

The world’s largest intact halophytic (salt-tolerating) mangrove forest is the Sundarbans, a UNESCO World Heritage Site that straddles India and Bangladesh. It forms the transition zone between the Ganges and the Bay of Bengal, and is a stronghold for the endangered Bengal tiger, as well as many other species, from monkeys to crocodiles.

The Sundarbans are dominated by Sterculiaceae and Euphorbiaceae mangroves, which are less common in most of the rest of the world. These include Sundari (Heritiera fomes) and looking-glass (Heritiera littoralis) mangroves. The hard wood of the latter was long used in boat building.

However, as a recent report by Dr. Md. Mizanur Rahman warns, these mangroves are in trouble. They face rising temperature, rising seas, silt and pollution washing down from deforested areas in the Himalaya, and pressures from aquaculture activities around the Sundarbans.

They are also being assaulted by rising salinity, brought by the formerly fresh rivers and streams that feed them. As agriculture increases in the region, water levels drop, minerals accumulate, and salinity rises. Brackish water is also expanding underground.

“Predictions from Sundarbans territory show that salinity may be double over the next few decades posing risks for survival of flora in Sundarbans,” writes Rahman.

He continued, “Natural vegetations of such areas are being destructed causing major changes in landscapes and biodiversity. Destruction of remaining natural habitats in core areas, buffer zones and corridors are also occurring. Most of the coastal districts already face severe salinity problems, with saline water pushing up to 250 km inward during the dry season.”

According to Rahman, Sundari trees and nypa palms are declining, changing the makeup of the ecosystem.

He added, “A salt concentration of 20-40% is suitable for mangrove ecosystems, while 40-80% diminishes the number of species and their size. Only a few species can exist and grow in 90% salt concentration. Sundari, Bain, Kakra, Passur and Dhondul tree species are being quickly replaced by Gewa and Keora.”

The fate of the Sundarbans mangroves lies both in how they can be protected locally, and in the health of the whole Ganges system. What happens upstream affects what comes down the pike.

Learn more about the world’s river basins, and how they affect us.

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 Yellowstone Supervolcano Eruptions More Frequent Than Thought? They may also be weaker—but could still affect much of the U.S.

Richard A. Lovett

for National Geographic News

Published May 1, 2012

The supervolcano underlying much of Yellowstone National Park and beyond may erupt more frequently than thought, a new study says.

What’s more, Yellowstone’s “super eruptions” may be slightly less super than suspected—but still strong enough to destroy all of Yellowstone and more, researchers say.

Much of Yellowstone National Park—which covers parts of Idaho, Montana, and Wyoming—lies in a roughly 40-mile-wide (70-kilometer-wide) crater formed by the collapse of a massive volcanic cone during the area’s most recent super-eruption, some 640,000 years ago.

Before then, Yellowstone had seen two other super-eruptions: one about a million years ago and another about two million years ago. Now, however, it seems the earliest blast might actually have been two cataclysmic explosions, thousands of years apart.

(Related: "Yellowstone Has Bulged as Magma Pocket Swells.")

Double Blast

Among geologists, it’s no secret that the two-million-year-old Yellowstone lava deposit has three layers.

"That got us thinking whether these things were representing different magma batches [from a single eruption] or different events," study leader Ben Ellis, a volcanologist and postdoctoral researcher at Washington State University, told National Geographic News.

Ellis’s team examined rock samples from all three layers using the latest isotope dating techniques, which rely on the known rates of decay of certain elements to date objects.

It turns out that the uppermost layer of the roughly two-million-year-old lava deposit—about 12 percent—was laid down about 6,000 years later than the other two layers, according to the study.

This suggests that the supervolcano’s active periods may span thousands of years and feature multiple massive eruptions—that “explosive volcanism from Yellowstone is more frequent than previously thought,” Ellis said in a statement.

The findings also raise the question of whether the other two layers represent separate eruptions, currently an unsolvable mystery, since even the latest dating techniques have relatively wide margins of error.

"Right now plus or minus 4,000 years is about as good as we can do [when dating] rocks of this age," Ellis said.

(Find out what’s really going on under Yellowstone and how the next super-eruption could unfold in "When Yellowstone Explodes" [National Geographic magazine, August 2009].)

Supervolcano Eruption Still “Definitely Big”

Though the team’s findings split that first Yellowstone super-eruption into two smaller blasts, Ellis points out that even the second, smaller eruption would have been an explosion for the ages.

"We just recognized an eruption 300 times the size of Mount St. Helens’," said Ellis, referring to the Washington State volcano’s 1980 eruption. (See pictures of Mount St. Helens before and after the blast.)

The larger of the two proposed blasts would still rank as the fourth largest eruption known to science. “It’s definitely big,” Ellis said. “We’re not taking that away.”

If something like that eruption were to happen today, he added, all of Yellowstone National Park would probably be devastated. What’s more, “the ashfall would likely be all over the continental U.S.,” he said.

Ellis refused to speculate about when such an eruption might occur again, but one thing’s for sure: Yellowstone—rising on a bulging magma pocket, seething with volcanically heated geysers and hot springs—is still very much alive.

The new Yellowstone-supervolcano study will appear in the June issue of the journal Quaternary Geochronology.

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Bioluminescent Organisms, Japan

Photograph by Paul A. Zahl

The transparent shells of tiny Cypridina hilgendorfii, found in the coastal waters and sands of Japan, hold a creature that emits a luminous blue substance when disturbed. During World War II, the Japanese harvested these creatures for soldiers to use when reading maps and messages at night.

(Photo shot on assignment for “Nature’s Night Lights—Probing the Secrets of Bioluminescence,” July 1971, National Geographic magazine)

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