Central Asia’s Water Tower

The Himalayas—which began forming about 50 million years ago when the Indian subcontinent started to collide with Eurasia—are arguably the world’s best-known snow-capped mountain range. But just to the north, beyond the Tarim Basin, the same tectonic forces that built the Himalayas also produced the Tien Shan, a similarly vast range of snow-capped peaks that extends 2,500 kilometers (1,500 miles) through Uzbekistan, Tajikistan, Kyrgyzstan, Kazakhstan, and western China.

The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA’s Terra satellite acquired this view of the sprawling range on October 9, 2012. It shows glacial ice with a layer of fresh snow covering the ice in many areas. (See this MODIS image from August 31, 2012, to see the same area with less snow.)

Geographers usually divide the Tien Shan into western, northern, central, and easterm ranges. The western and northern ranges have a milder and relatively moist climate, while the central and eastern ranges have a more severe climate, characterized by frigid winters and searing summers.

Many parts of the Tien Shan are cold enough to sustain glaciers. Some of the highest peaks and largest glaciers are clustered in the central range east of Lake Issyk-Kul, the large salt lake near the center of the image. Although the lake is surrounded by snow-capped mountains and situated at a high altitude, it does not generally freeze because of its high salinity.

Tien Shan’s glaciers play a crucial role in Central Asia’s hydrological cycle. An estimated 15 percent of freshwater runoff in Kyrgyzstan comes from glaciers, and the contribution can be much higher during the melting season, according to an analysis published in October 2012.

In the summer especially, cities such as Almaty, Bishkek, Tashkent, and Ürümqi rely heavily on freshwater from glaciers for irrigation and for household consumption, according to Annina Sorg, the Bern University researcher and lead author of the 2012 paper. Based on a review of numerous studies, she concluded that Tien Shan’s glaciers have retreated in recent decades due to changing climate conditions.

·      References

·      Sorg, A. (2012, July 29) Climate change impacts on glaciers and runoff in Tien Shan. Nature Climate Change.

·      Eurekalert (2012, July 29) Researchers analyze melting glaciers and water resources in Central Asia. Accessed Oct. 16, 2012.

·      European Space Agency (2011, Dec. 9) Earth from space: bumpy borders. Accessed Oct. 16, 2012.

Salar de Coipasa, Bolivia

The Salar de Coipasa, located in the Altiplano region of western Bolivia, covers an area of approximately 2,500 square kilometers (960 square miles). The word “salar” describes arid, closed basins in which evaporation of mineral-rich waters leads to the formation of thick, flat salt deposits. Salar de Coipasa is located to the southwest of the saline Lake Poopo and northwest of the largest salt flat in the world, Salar de Uyuni. At Coipasa, a crust composed of halite—common table salt—provides the brilliant white coloration characteristic of the Altiplano salars.

While the environment of Salar de Coipasa is arid, it does receive constant water from the Lauca River flowing in from the north. The Lauca feeds Lake (Lago) Coipasa, which covers the northern end of the basin with shallow water. However, the water flow can drop off sharply during periods of drought.

The waters of Lake Coipasa, and the white salt crust of the salar, also serve to highlight dark river sediments flowing into the basin along the northeastern shore. Dark volcanic rocks contrast sharply with the surrounding salt crust at image left. While the western Andes mountains contain many active volcanoes, the nearby Tata Sabaya volcano (not shown) has not been historically active.

Lost in migration: Earth's magnetic field overdue a flip

·         Reuters/Reuters - NASA undated handout image shows an image of the earth taken from space. REUTERS/NASA/JHandout

LONDON (Reuters) - The discovery by NASA rover Curiosity of evidence that water once flowed on Mars - the most Earth-like planet in the solar system - should intensify interest in what the future could hold for mankind.

The only thing stopping Earth having a lifeless environment like Mars is the magnetic field that shields us from deadly solar radiation and helps some animals migrate, and it may be a lot more fragile and febrile than one might think.

Scientists say earth's magnetic field is weakening and could all but disappear in as little as 500 years as a precursor to flipping upside down.

It has happened before - the geological record suggests the magnetic field has reversed every 250,000 years, meaning that, with the last event 800,000 years ago, another would seem to be overdue.

"Magnetic north has migrated more than 1,500 kilometres over the past century," said Conall Mac Niocaill, an earth scientist at Oxford University. "In the past 150 years, the strength of the magnetic field has lessened by 10 percent, which could indicate a reversal is on the cards."

While the effects are hard to predict, the consequences may be enormous. The loss of the magnetic Mac Niocaill said Mars probably lost its magnetic field 3.5-4.0 billion years ago, based on observations that rocks in the planet's southern hemisphere have magnetisation.

The northern half of Mars looks younger because it has fewer impact craters, and has no magnetic structure to speak of, so the field must have shut down before the rocks there were formed, which would have been about 3.8 billion years ago.

"With the field dying away, the solar wind was then able to strip the atmosphere away, and you would also have an increase in the cosmic radiation making it to the surface," he said.

"Both of these things would be bad news for any life that might have formed on the surface - either wiping it out, or forcing it to migrate into the interior of the planet."

RIGHT HERE, RIGHT NOW

Earth's magnetic field has always restored itself but, as it continues to shift and weaken, it will present challenges - satellites could be more exposed to solar wind and the oil industry uses readings from the field to guide drills.

In nature, animals which use the field could be mightily confused - birds, bees, and some fish all use the field for navigation. So do sea turtles whose long lives, which can easily exceed a hundred years, means a single generation could feel the effects.

Birds may be able to cope because studies have shown they have back-up systems that rely on stars and landmarks, including roads and power lines, to find their way around.

The European Space Agency is taking the issue seriously. In November, it plans to launch three satellites to improve our fairly blurry understanding of the magnetosphere.

The project - Swarm - will send two satellites into a 450 kilometre high polar orbit to measure changes in the magnetic field, while a third satellite 530 kilometres high will look at the influence of the sun.

field on Mars billions of years ago put paid to life on the planet if there ever was any, scientists say.

DESCENT INTO CHAOS

Scientists, who have known for some time the magnetic field has a tendency to flip, have made advances in recent years in understanding why and how it happens.

The field is generated by convection currents that churn in the molten iron of the planet's outer core. Other factors, such as ocean currents and magnetic rocks in the earth's crust also contribute.

The Swarm mission will pull all these elements together to improve computer models used to predict how the magnetic field will move and how fast it could weaken.

Ciaran Beggan, a geomagnetic specialist at the British Geological Survey in Edinburgh, said studies have also refined our understanding of how the field reverses.

They have focused on lava flows. When these cool and form crystals the atoms in iron-rich molten rock align under the influence of the magnetic field, providing a geological memory of the earth's field.

But that memory looks different in various locations around the world, suggesting the reversal could be a chaotic and fairly random process.

"Rather than having strong north and south poles, you get lots of poles around the planet. So, a compass would not do you much good," said Beggan.

While the whole process takes 3,000-5,000 years, latest research suggests the descent into a chaotic state could take as little as 500 years, although there are significant holes in scientific understanding.

"Although electricity grids and GPS systems would be more vulnerable, we are not really sure how all the complex things that are linked together would react," Beggan said.

(Editing by Dan Lalor)

When it rains, it pours

Study estimates rate of intensification of extreme tropical rainfall with global warming.

A warm rain will fall

Global warming’s effect on rainfall in general is relatively well-understood: As carbon dioxide and other greenhouse gases enter the atmosphere, they increase the temperature, which in turn leads to increases in the amount of water vapor in the atmosphere. When storm systems develop, the increased humidity prompts heavier rain events that become more extreme as the climate warms. 

Scientists have been developing models and simulations of Earth’s climate that can be used to help understand the impact of global warming on extreme rainfall around the world. For the most part, O’Gorman says, existing models do a decent job of simulating rainfall outside the tropics — for instance, in mid-latitude regions such as the United States and Europe. In those regions, the models agree on the rate at which heavy rains intensify with global warming.

However, when it comes to precipitation in the tropics, these models, O’Gorman says, are not in agreement with one another. The reason may come down to resolution: Climate models simulate weather systems by dividing the globe into a grid, with each square on the grid representing a wide swath of ocean or land. Large weather systems that span multiple squares, such as those that occur in the United States and Europe in winter, are relatively easy to simulate. In contrast, smaller, more isolated storms that occur in the tropics may be trickier to track. 

First Planets Found Around Sun-Like Stars in a Cluster

PASADENA, Calif. -- NASA-funded astronomers have, for the first time, spotted planets orbiting sun-like stars in a crowded cluster of stars. The findings offer the best evidence yet that planets can sprout up in dense stellar environments. Although the newfound planets are not habitable, their skies would be starrier than what we see from Earth.

The starry-skied planets are two so-called hot Jupiters, which are massive, gaseous orbs that are boiling hot because they orbit tightly around their parent stars. Each hot Jupiter circles a different sun-like star in the Beehive Cluster, also called the Praesepe, a collection of roughly 1,000 stars that appear to be swarming around a common center. 

The Beehive is an open cluster, or a grouping of stars born at about the same time and out of the same giant cloud of material. The stars therefore share a similar chemical composition. Unlike the majority of stars, which spread out shortly after birth, these young stars remain loosely bound together by mutual gravitational attraction. 

"We are detecting more and more planets that can thrive in diverse and extreme environments like these nearby clusters," said Mario R. Perez, the NASA astrophysics program scientist in the Origins of Solar Systems Program. "Our galaxy contains more than 1,000 of these open clusters, which potentially can present the physical conditions for harboring many more of these giant planets." 

The two new Beehive planets are called Pr0201b and Pr0211b. The star's name followed by a "b" is the standard naming convention for planets. 

"These are the first 'b's' in the Beehive," said Sam Quinn, a graduate student in astronomy at Georgia State University in Atlanta and the lead author of the paper describing the results, which was published in the Astrophysical Journal Letters. 

Volcano and Waterspout, Hawaii

Photograph by Steve and Donna O’Meara, National Geographic

The eruption of Hawaii’s Kilauea volcano inspires the formation of a waterspout in this undated photo.

Waterspouts can emerge the way traditional tornadoes do, but not always. Many are created

when near-surface winds suddenly change direction under a cloud that is producing a growing updraft. Unlike a tornado, a waterspout vortex and funnel cloud are created from the ground, or water, up.

Volcano Lightning, Iceland

Photograph by Sigurdur H. Stefnisson, National Geographic

Lightning cracks during an eruption of Iceland’s Eyjafjallajökull volcano in 2010.

The eruption’s ash clouds delayed European air travel for nearly a week.

Storms over volcanoes contain the same ingredients as storms over your hometown—water droplets, ice, and occasionally hail. The interaction of all of these elements creates an electrical charge that sparks lightning. Active craters add ash to the mix.

(Related: “Iceland Volcano Pictures: Lightning Adds Flash to Ash” and “Pictures: Volcano Lightning, Illuminated.”)

For an in-depth exploration of extreme weather events around the world, read National Geographic magazine's September feature "Weather Gone Wild."