Tropical Storm Erika nears Antigua en route to Puerto Rico

The fast-moving storm dumps rain on the eastern Caribbean.

Tropical Storm Erika is pictured in the Atlantic Ocean northeast of Venezuela in this NASA handout satellite photo of Wednesday. A fast-moving Tropical Storm Erika neared Antigua and Barbuda early on Thursday, dumping rain on the eastern Caribbean on a path expected to take it by Puerto Rico later in the day.

A fast-moving Tropical Storm Erika neared Antigua and Barbuda early on Thursday, dumping rain on the eastern Caribbean on a path expected to take it by Puerto Rico later in the day.

Across the region, officials ordered schools, airports and even casinos to close and they prepared shelters ahead of the storm, which was not expected to strengthen over the next two days.

Late Wednesday night, Erika was located about 110 miles (175 kilometres) east-southeast of Antigua and was moving west at 16 mph (26 kph) with a maximum sustained speed of 45 mph (75 kph), according to the National Hurricane Centre in Miami.

Flash floods warning

Authorities in Antigua and Barbuda warned of flash floods given the extremely dry conditions caused by the worst drought to hit the Caribbean in recent years. Boats at Shell Beach Marina on Antigua’s north coast have been out of the water since Saturday, with people not taking chances as Erika approaches, said Caroline Davy, a marina employee.

She said many people were caught off-guard when Tropical Storm Gonzalo battered Antigua last October.

“Too many times we’ve seen things happen that were not predicted,” she said.

No business as usual

Authorities in the nearby Dutch Caribbean territory of St. Maarten said schools and government offices would close on Thursday. They also asked that casinos, restaurants and other businesses close by midnight on Wednesday. Officials warned they might temporarily suspend power and water service as the storm approaches.

The hurricane centre said Erika would move near Puerto Rico and the Virgin Islands on Thursday.

All airports in the U.S. Virgin Islands would be closed to incoming flights until Friday, and government offices would close as well, said Gov. Kenneth Mapp.

“This is a fast-moving storm, and so we expect conditions to deteriorate rapidly,” he said.

Storm watch

Tropical storm warnings were issued for Puerto Rico, the U.S. and British Virgin Islands and the Leeward Islands. A tropical storm watch was in effect for the northern Dominican Republic, the Turks & Caicos Islands and south-eastern Bahamas.

The storm is expected to be near South Florida by Monday, according to James Franklin, chief hurricane forecaster at the Miami-based centre. But its intensity is still uncertain.

“We don’t know how much of the storm will be left,” he said, adding that it faced strong upper-level westerly winds in the next two to three days.

Ignacio now a hurricane

Meanwhile in the Pacific, Ignacio strengthened into a hurricane. The storm’s maximum sustained winds increased to 75 mph (120 kph).

Source: The Hindu

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#2015, #27, #august

Discovery of a salamander in amber sheds light on evolution of Caribbean islands

A salamander found preserved in amber from the Dominican Republic is the first-ever fossil of its kind, and also shows that salamanders once lived in the Caribbean region, where they now are all extinct.

More than 20 million years ago, a short struggle took place in what is now the Dominican Republic, resulting in one animal getting its leg bitten off by a predator just before it escaped. But in the confusion, it fell into a gooey resin deposit, to be fossilized and entombed forever in amber.

The fossil record of that event has revealed something not known before — that salamanders once lived on an island in the Caribbean Sea. Today, they are nowhere to be found in the entire Caribbean area.

The never-before-seen and now extinct species of salamander, namedPalaeoplethodon hispaniolae by the authors of the paper, adds more clues to the ecological and geological history of the islands of the Caribbean. Findings about its brief life and traumatic end — it was just a baby — have been published in the journal Palaeodiversity, by researchers from Oregon State University and the University of California at Berkeley.

“I was shocked when I first saw it in amber,” said George Poinar, Jr., a professor emeritus in the OSU College of Science, and a world expert in the study of insects, plants and other life forms preserved in amber, all of which allow researchers to reconstruct the ecology of ancient ecosystems.

“There are very few salamander fossils of any type, and no one has ever found a salamander preserved in amber,” Poinar said. “And finding it in Dominican amber was especially unexpected, because today no salamanders, even living ones, have ever been found in that region.”

This fossil salamander belonged to the family Plethodontidae, a widespread family that today is still very common in North America, particularly the Appalachian Mountains. But it had back and front legs lacking distinct toes, just almost complete webbing with little bumps on them. As such, it might not have been as prolific a climber as some modern species, Poinar said, and it probably lived in small trees or tropical flowering plants.

This specimen, Poinar said, came from an amber mine in the northern mountain range of the Dominican Republic, between Puerto Plata and Santiago.

“The discovery of this fossil shows there once were salamanders in the Caribbean, but it’s still a mystery why they all went extinct,” Poinar said. “They may have been killed by some climatic event, or were vulnerable to some type of predator.”

Also a mystery, he said, is how salamanders got there to begin with. The physical evidence suggests the fossil represents an early lineage of phethodon salamanders that evolved in tropical America.

This fossil is 20-30 million years old, and its lineage may go back 40-60 million years ago when the Proto-Greater Antilles, that now include islands such as Cuba, Jamaica, Puerto Rico and Hispaniola, were still joined to North and South America. Salamanders may have simply stayed on the islands as they began their tectonic drift across the Caribbean Sea. They also may have crossed a land bridge during periods of low sea level, or it’s possible a few specimens could have floated in on debris, riding a log across the ocean.

Such findings, Poinar said, help both ecologists and geologists to reconstruct ancient events of Earth’s history.

“There have been fossils of rhinoceroses found in Jamaica, jaguars in the Dominican Republic, and the tree that produced the Dominican amber fossils is most closely related to one that’s native to East Africa,” Poinar said. “All of these findings help us reconstruct biological and geological aspects of ancient ecosystems.”

Source: SD

#2015, #august

Fossil study: Dogs evolved with climate change

A cooling, drying climate over the last 40 million years turned North America from a warm and wooded place into the drier, open plains we know today. A new study shows how dogs evolved in response to those changes, demonstrating that predators are sensitive to climate change because it alters the hunting opportunities in their habitat.

Old dogs can teach humans new things about evolution. In Nature Communications a new study of North American dog fossils as old as 40 million years suggests that the evolutionary path of whole groups of predators can be a direct consequence of climate change.

“It’s reinforcing the idea that predators may be as directly sensitive to climate and habitat as herbivores,” said Christine Janis, professor of ecology and evolutionary biology at Brown University, who worked with lead author Borja Figueirido, a former Brown Fulbright postdoctoral researcher who is now a professor at the Universidad de Málaga in Spain. “Although this seems logical, it hadn’t been demonstrated before.”

The climate in North America’s heartland back around 40 million years ago was warm and wooded. Dogs are native to North America. The species of the time, fossils show, were small animals that would have looked more like mongooses than any dogs alive today and were well-adapted to that habitat. Their forelimbs were not specialized for running, retaining the flexibility to grapple with whatever meal unwittingly walked by.

But beginning just a few million years later, the global climate began cooling considerably and in North America the Rocky Mountains had reached a threshold of growth that made the continental interior much drier. The forests slowly gave way to open grasslands.

Pups of the plains

Did this transition affect the evolution of carnivores? To find out, Figueirido and the research team, including Jack Tseng of the American Museum of Natural History in New York, examined the elbows and teeth of 32 species of dogs spanning the period from ca. 40 million years ago to 2 million years ago. They saw clear patterns in those bones at the museum: At the same time that climate change was opening up the vegetation, dogs were evolving from ambushers to pursuit-pounce predators like modern coyotes or foxes — and ultimately to those dogged, follow-a-caribou-for-a-whole-day pursuers like wolves in the high latitudes.

“The elbow is a really good proxy for what carnivores are doing with their forelimbs, which tells their entire locomotion repertoire,” Janis said.

The telltale change in those elbows has to do with the structure of the base where the humerus articulates with the forearm, changing from one where the front paws could swivel (palms can be inward or down) for grabbing and wrestling prey to one with an always downward-facing structure specialized for endurance running. Modern cats still rely on ambush rather than the chase (cheetahs are the exception) and have the forelimbs to match, Janis said, but canines signed up for lengthier pursuits.

In addition, the dogs’ teeth trended toward greater durability, Figueirido’s team found, consistent perhaps with the need to chow down on prey that had been rolled around in the grit of the savannah, rather than a damp, leafy forest floor.

Not an ‘arms race’ of limbs

The study, with some of Janis’ prior research, suggests that predators do not merely evolve as an “arms race” response to their prey. They don’t develop forelimbs for speedy running just because the deer and the antelope run faster. While the herbivores of this time were evolving longer legs, the predator evolution evident in this study tracked in time directly with the climate-related changes to habitat rather than to the anatomy of their prey species.

After all, it wasn’t advantageous to operate as a pursuit-and-pounce predator until there was room to run.

“There’s no point in doing a dash and a pounce in a forest,” Janis quipped. “They’ll smack into a tree.”

If predators evolved with climate change over the last 40 million years, the authors argue, then they likely will have to continue in response to the human-created climate change underway now. The new results could help predict the effects we are setting in motion.

“Now we’re looking into the future at anthropogenic changes,” Janis said.

Source: SD

#2015, #august

Amazon fire risk linked to devastating hurricanes

Researchers have uncovered a remarkably strong link between high wildfire risk in the Amazon basin and the devastating hurricanes that ravage North Atlantic shorelines. The climate scientists’ findings appear near the 10th anniversary of Hurricane Katrina’s calamitous August 2005 landfall at New Orleans.

“Hurricane Katrina is indeed part of this story,” said James Randerson, Chancellor’s Professor of Earth system science at UCI and senior author on the paper. “The ocean conditions that led to a severe hurricane season in 2005 also reduced atmospheric moisture flow to South America, contributing to a once-in-a-century dry spell in the Amazon. The timing of these events is perfectly consistent with our research findings.”

Lead author Yang Chen discovered that in addition to the well-understood east-west influence of El Niño on the Amazon, there’s also a north-south control on fire activity that’s set by the state of the tropical North Atlantic. Warm ocean waters help hurricanes develop and gather strength and speed on their way to North American shores. They also tend to pull a large belt of tropical rainfall — known as the Intertropical Convergence Zone — to the north, Chen said, drawing moisture away from the southern Amazon and leading to heightened fire risk over time.

“North Atlantic hurricanes and Amazon fires are related to one another through shared linkages to ocean-atmosphere interactions in the tropical Atlantic Ocean,” he said.

The mechanics of the ocean-fire link in the Amazon are fairly straightforward. When the North Atlantic sea surface temperatures are warmer than normal, less rain falls in the southern Amazon. As a consequence, groundwater is not fully recharged by the end of the rainy season. Coming into the next dry spell, when there’s less water stored away in the soil, plants can’t evaporate and transpire as much water out through their stems and leaves. As a result, the atmosphere gets drier and drier, creating conditions in which fires can spread rapidly. Ground-clearing fires set by farmers for agricultural purposes can easily jump from fields to dense forests under these conditions.

“Understory fires in Amazon forests are extremely damaging, since most rainforest trees are not adapted to fire,” noted co-author Douglas Morton of NASA’s Goddard Space Flight Center in Greenbelt, Md. “The synchronization of forest damages from fires in South America and tropical storms in North America highlights how important it is to consider the Earth as a system.”

The team pored over years of historical storm and sea surface temperature data from the National Oceanic & Atmospheric Administration and fire data gathered by NASA satellites. The results showed a striking pattern, a progression over the course of several months from warm waters in the tropical North Atlantic to a dry and fire-prone southern Amazon and more destructive hurricane landfalls in North and Central America.

According to Randerson, the importance of this study is that it may help meteorologists develop better seasonal outlooks for drought and fire risk in the Amazon, leveraging investments by NOAA and other agencies in understanding hurricanes. The research findings also give policymakers throughout the hemisphere a basis for decisions about coastal protections in hurricane-prone areas and fire management in drought-affected areas.

“The fires we see in the U.S. West are generally lightning-ignited, whereas they’re mostly human-ignited in the Amazon, but climate change can have really large effects on the fire situation in both regions,” Randerson said. “Keeping fire out of the Amazon basin is critical from a carbon-cycle perspective. There’s a huge amount of carbon stored in tropical forests; we really want to keep the forests intact.”

Randerson and Chen credit NASA and NOAA for providing free public access to real-time data from their satellites and other sensors and the Gordon & Betty Moore Foundation, NASA and the U.S. Department of Energy’s Office of Science for research support.

“Drought in the Amazon and hurricanes in the North Atlantic are such costly and potentially catastrophic disturbances [that] we really rely on NASA and NOAA for help in making accurate forecasts and long-range predictions,” Randerson said.

Source: SD

#2015, #august

Go organic in a big way, farmers told

Agriculture is a profitable venture, sustain it

K. Ventakeshwara Rao, Chief General Manager, Nabard, inspecting a mini tiller at a stall at the agriculture fair that began in Salem on Friday.– Photo:S. Guruprasath

The four day ‘Agri-expo 2015’ got underway in the city on Friday evening, with a call to the government, government agencies, and other organisations involved in the promotion of agriculture to create confidence in the minds of farmers that agriculture is not only a vital profession but profit making too.

The exhibition is brought up jointly by the Salem District Agriculture Graduates Advisory and Service Society, Confederation of Indian Industry (CII) Salem, and Kontak Exhibitions and Fairs at the Deiveegam Marriage Hall, Fairlands here.

Good sign

Inaugurating the fair, K. Venkateshwara Rao, Chief General Manager, Nabard, said that organic cultivation was slowly returning, which was a good sign.

Organic cultivation has to be promoted in the country irrespective of its impact.

The farmers could also be motivated to adopt a combination of organic and inorganic cultivation techniques in a scientific way.

Mr. Venkateshwara Rao said that the farmers, so also the people, have totally forgotten the minor millets, which played a crucial role in the food production of the country till recent past. For various reasons, the people have started opting for only wheat and rice.

Various minor millets feasible in the particular areas should be promoted and this will go a long way in meeting the food demand of the country, he said.

Revenue

Farmers at present are worried at the steep fall in revenue in the farm activities and many of them switching over to other trades. It is the duty of all concerned to encourage the farmers. The latest farming technologies should be taken to the fields, so that farmers stand benefited.

Produce fund

Explaining the financial support rendered for farm activities by the government and banks, Mr. Venkateshwara Rao said that the Union Government has created a separate ‘produce fund.’ K.M.S. Rajesh Kumar, chairman, CII Salem, said that the agriculture panel of the CII will always extend a helping hand for such endeavours.

A. Bhama Bhuvaneswari, District Development Manager, Nabard, said that the farmers of the region have taken advantage of similar fairs held in the past.

Two Farmers Clubs promoted by Nabard have put up stalls, she said and added that Nabard will extend all support for such interactions.

S. Mohan, former chairman, CII, Salem; M. Ramasamy, chairman, Rasi Seeds, Attur; S. Vimalan, vice-chairman, CII Salem, and others spoke.

A. Sadiq Basha, district governor, Lions District 324 B2, inaugurated the medical camp.

Banks, State Horticulture Department, Silk Development Department, Krishi Vigyan Kendras, Sandhiyur, Dindivanam and Papparapatti, Tapioca and Castor Research Station, Yethapur, Farmers Clubs too have put up stalls.

Source: TH

#15, #2015, #august

Greenland ice sheet’s winds driving tundra soil erosion, study finds

Strong winds blowing off the Greenland Ice Sheet are eroding soil and vegetation in the surrounding tundra, making it less productive for caribou and other grazing animals, carbon storage and nutrient cycling, a study finds.

Arctic soils are a critical but fragile ecological resource threatened by wildfire, permafrost degradation and other climate-related disturbances that are well studied. But wind-driven soil erosion has not been well documented, especially in western Greenland where it poses the greatest threat to soil stability.

The findings appear in the journal Annals of the Association of American Geographers.

“Understanding the current distribution of wind-eroded patches is a first step toward a more complete picture of regional wind erosion and its ecological impacts, especially as the Arctic continues to experience rapid environmental change and warming temperatures,” says lead author Ruth Heindel, a Ph.D. student in Dartmouth’s Department of Earth Sciences and a fellow in the IGERT Polar Environmental Change program.

The researchers used satellite imagery and remote sensing techniques to analyze wind erosion in the Kangerlussuaq region of western Greenland, where bare ground patches around the ice sheet are much less productive than the surrounding landscape. The region’s soils have developed on a layer of loess, or loose sediment that is easily eroded by the wind.

The researchers wanted to know if soil erosion is controlled by proximity to the ice sheet or by the lay of the land, including the direction and steepness of nearby hillsides. In addition, they considered whether bare patches near the ice sheet are similar in size, distribution and denudation as those farther away since wind patterns, vegetation and climate all vary with distance from the ice sheet. Winds blowing off the ice sheet tend to be drier and colder than those coming off the fjord.

Results showed that bare patches covered 22 percent of the land in the study area, ranging in size from about 100 square feet to more than 1,000 square feet. The bare patches were more widespread near the ice sheet but restricted to steep south-facing slopes farther away from the ice sheet. This pattern suggests that strong downslope winds blowing off the ice sheet are responsible for the soil erosion. In addition, the eroded patches close to the ice sheet contain less vegetation than those farther away.

The vegetation around the eroded areas is a mixture of shrubs and grasses, but grasses dominate within the eroded patches. Across the Arctic, shrub species are expanding into grass habitat, but the new findings show how wind erosion may limit the spread of shrubs by providing better habitat for grasses or an environment dominated by lichens, mosses, cyanobacteria and microfungi.

The findings are a snapshot of current soil erosion in western Greenland rather than an analysis of changes over time, which the researchers are currently conducting. The Greenland Ice Sheet has experienced record melting in recent years, but it is relatively stable in western Greenland. If the ice sheet retreats in this region, soil erosion is expected to be more restricted to steep south-facing slopes, but the already bare patches could remain denuded for a long time.

Source: SD

#17, #2015, #august

Ascent or no ascent? How hot material is stopped in Earth’s mantle

Gigantic volumes of hot material rising from the deep earth’s mantle to the base of the lithosphere have shaped the face of our planet. Provided they have a sufficient volume, they can lead to break-up of continents or cause mass extinction events in certain periods of the Earth’s history. So far it was assumed that because of their high temperatures those bodies — called mantle plumes — ascend directly from the bottom of the earth’s mantle to the lithosphere. Scientists explain possible barriers for the ascent of these mantle plumes and under which conditions the hot material can still reach the surface. In addition, the researchers resolve major conflicts surrounding present model predictions.

The largest magmatic events on Earth are caused by massive melting of ascending large volumes of hot material from Earth’s interior. The surface manifestations of these events in Earth’s history are still visible in form of the basaltic rocks of Large Igneous Provinces. The prevailing concept of mantle plumes so far was that because of their high temperatures, they have strongly positive buoyancy that causes them to ascend and uplift the overlying Earth’s surface by more than one kilometer. In addition, it was assumed that these mantle plumes are mushroom-shaped with a large bulbous head and a much thinner tail with a radius of only 100 km, acting as an ascent channel for new material. But here is the problem: In many cases, this concept does not agree with geological and geophysical observations, which report much wider zones of ascending material and much smaller surface uplift.

The solution is to incorporate observations from plate tectonics: In many places on Earth’s surface, such as in the subduction zones around the Pacific, ocean floor sinks down into Earth’s mantle. Apparently, this material descends up to a great depth in Earth’s mantle over several millions of years. This former ocean floor has a different chemical composition than the surrounding Earth’s mantle, leading to a higher density. If this material is entrained by mantle plumes, which is indicated by geochemical analyses of the rocks of Large Igneous Provinces, the buoyancy of the plume will decrease. However, this opens up the question if this hot material is still buoyant enough to rise all the way from the bottom of Earth’s mantle to the surface.

GFZ-researcher Juliane Dannberg: “Our computer simulations show that on the one hand, the temperature difference between the plume and the surrounding mantle has to be high enough to trigger the ascent of the plume. On the other hand, a minimum volume is required to cross a region in the upper mantle where the prevailing pressures and temperatures lead to minerals with a much higher density than the surrounding rocks.”

Under these conditions, mantles plumes with very low buoyancy can develop, preventing them from causing massive volcanism and environmental catastrophes, but instead making them pond inside of Earth’s mantle. However, mantle plumes that are able to ascend through the whole mantle are much wider, remain in Earth’s mantle for hundreds of millions of years and only uplift the surface by a few hundred meters, which agrees with observations.

Source: SD

#17, #2015, #august

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