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Geochemical ‘fingerprints’ leave evidence that megafloods eroded steep gorge

By Guest PostAugust 10, 2013Environmentassam valley, bay of bengal, brahmaputra river, columbia river basin, david montgomery, downstream, evidence, ganges river delta, geochemical fingerprints, geochemical signature, giant dam, heavy mineral, himalaya mountains, hydroelectric generation, ilmenite, India, karl lang, katharine huntington, lake erie, lake michigan, lake missoula, magnetite, megafloods, namche barwa, prehistoric megaflood, southern asia, steep gorge, tibetan plateau, tsangpo gorge, university of washington, uranium bearing zircon, western montana, yarlung tsangpo river, yiggong river

The Yarlung-Tsangpo River in southern Asia drops rapidly through the Himalaya Mountains on its way to the Bay of Bengal, losing about 7,000 feet of elevation through the precipitously steep Tsangpo Gorge.

For the first time, scientists have direct geochemical evidence that the 150-mile long gorge, possibly the world’s deepest, was the conduit by which megafloods from glacial lakes, perhaps half the volume of Lake Erie, drained suddenly and catastrophically through the Himalayas when their ice dams failed at times during the last 2 million years. (more…)

Scientists Explore Roots of Future Tropical Rainfall

By Guest PostJune 10, 2013Environmentarabian sea, atmosphere, bay of bengal, climate prediction, earth, eastern africa, eastern indian ocean, evidence, future tropical rainfall, geological clues, hadley centre, indian, indo-pacific, indonesia, jessica tierney, last glacial maximum, last ice age, northern australia, numerical models, pacific regions, pedro dinezio, proxies, proxy evidence, rainfall patterns, roots, salinity, saltier waters, southeast asia, sunda shelf, surface waters, tropical climate change, university of hawaii, warm pool, western pacific, wetter

Analysis of the Last Glacial Maximum sheds light on climate models’ ability to simulate tropical climate change

How will rainfall patterns across the tropical Indian and Pacific regions change in a future warming world? Climate models generally suggest that the tropics as a whole will get wetter, but the models don’t always agree on where rainfall patterns will shift in particular regions within the tropics.

A new study, published online May 19 in the journal Nature Geoscience, looks to the past to learn about the future of tropical climate change, and our ability to simulate it with numerical models. (more…)

NASA’s Aquarius Sees Salty Shifts

By Guest PostMarch 1, 2013Environmentafrica, amazon river mouth, aquarius, aquarius instrument, arabian sea, argentine built, bay of bengal, caribbean, changing global climate, chronicle, cold polar waters, conae, cycling of freshwater, eastern tropical pacific, eric lindstrom, flag data, ganges, gary lagerloef, gene carl feldman, global rainfall patterns, heavy rain, ice free oceans, land contamination, large freshwater plume, mediterranean sea, microwave emissions, microwave radiometer, middle east, monsoon rains, NASA, ocean circulation, ocean salinity patterns, ocean salinity satellite, panama coast, pulses of freshwater, salinity processes, salinity variations, salty arabian sea, salty shifts, salty world, seasonal stirrings, smos, soil moisture, spacecraft, spurs, surface salinity data, varying salinity patterns, winter

The colorful images chronicle the seasonal stirrings of our salty world: Pulses of freshwater gush from the Amazon River’s mouth; an invisible seam divides the salty Arabian Sea from the fresher waters of the Bay of Bengal; a large patch of freshwater appears in the eastern tropical Pacific in the winter. These and other changes in ocean salinity patterns are revealed by the first full year of surface salinity data captured by NASA’s Aquarius instrument.

“With a bit more than a year of data, we are seeing some surprising patterns, especially in the tropics,” said Aquarius Principal Investigator Gary Lagerloef, of Earth & Space Research in Seattle. “We see features evolve rapidly over time.” (more…)

Landslides Linked to Plate Tectonics Create the Steepest Mountain Terrain

By Guest PostJune 3, 2012Environmentangle of slope, bay of bengal, bedrock, brahmaputra river, catastrophic breach, david montgomery, delta, downstream, eastern himalaya, Ganges River, isaac larsen, landslide, landslide erosion, mountain slopes, mountain terrain, plate tectonics, po tsangpo river, river, southeast tibet, southern asia, spy satellite photography, terrain uplift, tsangpo gorge, university of washington, vince stricherz, yarlung tsangpo river

Some of the steepest mountain slopes in the world got that way because of the interplay between terrain uplift associated with plate tectonics and powerful streams cutting into hillsides, leading to erosion in the form of large landslides, new research shows.

The work, presented online May 27 in Nature Geoscience, shows that once the angle of a slope exceeds 30 degrees – whether from uplift, a rushing stream carving away the bottom of the slope or a combination of the two – landslide erosion increases significantly until the hillside stabilizes.

“I think the formation of these landscapes could apply to any steep mountain terrain in the world,” said lead author Isaac Larsen, a University of Washington doctoral student in Earth and space sciences. (more…)

Study Links Past Changes in Monsoon to Major Shifts in Indian Civilizations

By Guest PostMarch 15, 2012Environmentasia, band of heavy rain, bay of bengal, camilo ponton, civilizations, climate change, cmz, core monsoon zone, dorian fuller, drilling vessel, drought, equator, eth, global warming, godavari river, harappan civilization, humid monsoon, India, indian monsoon, indian peninsula, insolation, inter tropical convergence zone, itcz, joides resolution, liviu giosan, modern agriculture, monsoon, northern hemisphere, ocean, paleo climatic information, plankton fossil, sahara desert, sediment core, solar radiation, tim eglinton, tropical forest, vegetation, whoi, zurich

A fundamental shift in the Indian monsoon has occurred over the last few millennia, from a steady humid monsoon that favored lush vegetation to extended periods of drought, reports a new study led by researchers at the Woods Hole Oceanographic Institution (WHOI). The study has implications for our understanding of the monsoon’s response to climate change.

The Indian peninsula sustains over a billion people, yet it lies at the same latitude as the Sahara Desert. Without a monsoon, most of India would be dry and uninhabitable. The ability to predict the timing and amount of the next year’s monsoon is vital, yet even our knowledge of the monsoon’s past variability remains incomplete. (more…)

Aquarius Yields NASA’s First Global Map of Ocean Salinity

By Guest PostSeptember 25, 2011Environment, Scienceamazon river, aquarius, arabian sea, arnold gordon, bay of bengal, calibration and validation, climate, climate variations, first global map of the salinity, Ganges River, gary lagerloef, global rainfall, indian subcontinent, michael freilich, NASA, ocean circulation, ocean currents, ocean surface, ocean surface salinity, pacific and indian oceans, patterns of rainfall and evaporation over the ocean, river outflow, sac d, salinity changes, salinity in the atlantic ocean, salinity patterns, satélite de aplicaciones científicas, south asia monsoon rains

PASADENA, Calif. – NASA’s new Aquarius instrument has produced its first global map of the salinity of the ocean surface, providing an early glimpse of the mission’s anticipated discoveries.

Aquarius, which is aboard the Aquarius/SAC-D (Satélite de Aplicaciones Científicas) observatory, is making NASA’s first space observations of ocean surface salinity variations — a key component of Earth’s climate. Salinity changes are linked to the cycling of freshwater around the planet and influence ocean circulation. (more…)

‘Sea Levels Rising in Parts of Indian Ocean’

By Guest PostJuly 15, 20102 commentsEnvironmentafrica, Antarctica, arabian sea, atmospheric, balaji rajagopalan, Bangladesh, bay of bengal, global climate, greenhouse gases, India, indian ocean, indo-pacific, Java, mascarenhas archipelago, naval research laboratory in Mississippi, ncar, sea levels, seychelles Islands, sri lanka, sumatra, Tanzania, university of colorado at boulder, weiqing han, Zanzibar

*Greenhouse gases are playing a role in changes, say scientists*

Newly detected rising sea levels in parts of the Indian Ocean, including the coastlines of the Bay of Bengal, the Arabian Sea, Sri Lanka, Sumatra and Java, appear to be at least partly a result of human-induced increases of atmospheric greenhouse gases, says a study led by the University of Colorado at Boulder.

(more…)

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