Would you like to decorating your walls with those plants ?
Green roofs help to reduce the heat island effect in towns and cities because plants absorb less heat than concrete and can also cool the air via the process of evapotranspiration. This can save energy by cutting the need for air conditioning on hot days. What's more, they reduce the risk of flooding by absorbing water and, of course, they absorb carbon dioxide.
Most existing green roofs use various species of Sedum, because the plants can survive without rain for long periods, meaning they require little maintenance.
But Tijana Blanusa, a Royal Horticultural Society researcher based at the University of Reading in the UK, wanted to know if Sedum really is the best plant for the job.
She compared a variety of plants, including a Sedum mix, lamb's ear andelephant ear, to see if differences in leaf shape and structure would make a difference to the temperature of the air above them.
She found that lamb's ear, a silvery, hairy-leafed plant, had the consistently coolest leaves over a two-year period. "Even when it is really stressed, and the leaves of other plants get a few degrees warmer than when they are watered, the lamb's ear manages to keep its leaves cooler than those that don't have hairs," she says.
What's more, when she measured the air temperature 20 centimetres above each plant, she found that on the hottest summer afternoons the air above lamb's ear was also cooler than above the other plants.
Hope this article helps you out..... ^_^
The Alpha Centauri dual star system is thought to host rocky Earth-mass worlds, but this assumes they could form in the turbulent conditions associated with the opposing gravitational tugs of paired star systems.
Rocky planets are created from the merger of moon-sized planetary embryos which, in turn, form from the accretion of kilometre-sized planetesimals. However, there is no guarantee that such embryos could form in turbulent conditions.
To find out, Jian Ge of the University of Florida in Gainesville and colleagues built a computer simulation of Alpha Centauri, which showed that moon-sized protoplanets could indeed form after about a million years. No gas giants would be created though, as any gas would be dispersed by the turbulent conditions.
Phillipe Thebault of the Observatory of Paris in France describes the work as interesting, but says the issue is still far from settled. It is impossible to numerically study the planet accretion process in a turbulent system, such as Alpha Centauri, without some simplification, he says.
Rajendra Pachauri, the chairman of the IPCC, conceded yesterday that "the clear and well-established standards of evidence required by the IPCC procedures were not applied properly" when the claim was included in the 900-page assessment of the impacts of climate change.
The paragraph at issue reads: "Glaciers in the Himalaya are receding faster than in any other part of the world and, if the present rate continues, the likelihood of them disappearing by the year 2035 and perhaps sooner is very high."
The report's only cited source was a 2005 report by the environment group WWF, which in turn cited a 1999 article in New Scientist.
The New Scientist article quoted senior Indian glaciologist Syed Hasnain, the then vice-chancellor of Jawaharlal Nehru University in New Delhi, who was writing a report on the Himalayas for the International Commission for Snow and Ice. It said, on the basis of an interview with Hasnain, that his report "indicates that all the glaciers in the central and eastern Himalayas could disappear by 2035". The claim did not, however, appear in the commission's report, which was only made available late last year.
This week a group of geographers, headed by Graham Cogley of Trent University at Peterborough in Ontario, Canada, have written to the journal Science pointing out that the claim "requires a 25-fold greater loss rate from 1999 to 2035 than that estimated for 1960 to 1999. It conflicts with knowledge of glacier-climate relationships, and is wrong."
The geographers add that the claim has "captured the global imagination and has been repeated in good faith often, including recently by the IPCC's chairman". The IPCC's errors "could have been avoided had the norms of scientific publication, including peer review and concentration upon peer-reviewed work, been respected", they say.
Several of those involved in the IPCC review process did try to question the 2035 date before it was published by the IPCC. Among them was Georg Kaser, a glaciologist from the University of Innsbruck, Austria, and a lead author of another section of the IPCC report. "I scanned the almost final draft at the end of 2006 and came across the 2035 reference." Kaser queried the reference but believes it was too late in the day for it to be reassessed.
Publicly available IPCC archives of the review process show that during the formal review, the Japanese government also questioned the 2035 claim. It commented: "This seems to be a very important statement. What is the confidence level/certainty?" Soon afterwards, a reference to the WWF report was added to the final draft. But the statement otherwise went unchanged.
One of the IPCC authors, Stephen Schneider of Stanford University, California, this week defended the use of so-called "grey" literature in IPCC reports. He told New Scientist that it was not possible to include only peer-reviewed research because, particularly in the chapters discussing the regional impacts of climate change, "most of the literature is not up to that gold standard".
The Himalaya claim appeared in the regional chapter on Asia. "There are only a few authors in each region, so it narrows the base of science," Schneider says.
Source : Many sources
Comets from outer space may have created Earth's atmosphere – not volcanoes spewing out gases from deep within the planet.
The origin of the gases in Earth's atmosphere has long been a puzzle. One of the main theories is that the gases bubbled up out of the mantle via volcanoes.
Greg Holland of the University of Manchester, UK, and colleagues have arrived at a different theory after collecting samples of the noble gas krypton from several hundred metres beneath New Mexico.
They found that the mantle's chemical fingerprint was rich in "heavy" isotopes of krypton such as krypton-86 and krypton-84, and poorer in "lighter" forms such as krypton-82. This is a composition that closely resembles meteorites –- support for the ideas that gas-rich meteorites colliding in the early solar system formed our planet.
"The results confirm one of the basic ideas of planetary formation theory, that most of the Earth formed by collisions of smaller objects like carbonaceous chondrites," says Scott Kenyon at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.
But where did the atmosphere come from –- it is rich in lighter isotopes so the mantle cannot be the source, says Holland. Earth's atmosphere cannot have gained a greater proportion of lighter isotopes since it formed. Because light isotopes of krypton escape into space more quickly than heavy isotopes, the atmosphere can only get "heavier"
If not the mantle then what? Chris Ballentine, a co-author and colleague of Holland's suggests that comets could be the answer. At the outer edges of the solar system, in the Kuiper Belt, are millions of icy bodies that formed when the solar system was born. These comets have noble gas signatures that resemble that of our modern atmosphere.
A shift in Jupiter's orbit around 4.5 billion years ago may have jarred the Kuiper Belt, flinging icy comets at the Earth. "Ancient Earth was strewn with huge volcanoes spewing out gas, but our research shows that the real source of Earth's first atmosphere was actually outer space," says Ballentine, a co-author of the paper and colleague of Holland's.
Source: Science, DOI: 10.1126/science.1179518
The earthquake which devastated the city of Padang in Sumatra, Indonesia, this week, killing more than 1100 people, may have been only a hint of worse to come. Since 2004, geologists have been predicting a far nastier earthquake in the region – a shallow tremor that will rip the sea floor apart, trigger a devastating tsunami and kill far more people.
"Another earthquake is on its way, and all it will take to trigger it is the pressure of a handshake," says John McCloskey, a seismologist at the Environmental Sciences Research Institute at the University of Ulster in Coleraine, Northern Ireland.
Padang experienced a magnitude-7.6 earthquake on 30 September, just after 5 pm local time. Images of terrified relatives waiting to identify dead bodies, their T-shirts clutched over their noses to mask the stench, military officials stalking between bright yellow, zipped-up body bags and centuries-old Dutch colonial mansions obliterated in an instant have flooded around the world.
At first, geologists assumed this was the earthquake they had predicting for many years. "Padang has bad geology," explains McCloskey. "It sits 40 kilometres above the most earthquake-prone stretch of the interface between the Indo-Australian and Eurasian plates."
This interface has not experienced the stress relief of an earthquake for over 200 years, according to McCloskey's analysis of historical coral growth rings, which show no sign of seafloor uplift. GPS measurements of the rate of plate motion suggest that there has been around 13 metres of movement in this area over the same period. "A shallow earthquake at the plate interface off Padang is long, long overdue," says McCloskey.
Yet the earthquake which struck this week off Padang did not occur at the plate interface, which lies 500 kilometres offshore. The epicentre was just 45 kilometres from Padang, far away from the plate interface. What's more, it originated 80 kilometres underground, far deeper than the place at which the Indo-Australian and Eurasian plates crunch together.
Further evidence comes from the orientation of the rupture caused by this week's quake. "The rupture spread in a north-south orientation, rather than east-to-west, as we would expect along the plate interface," says McCloskey.
All the clues add up to the earthquake being a freak rupture of an ancient stressed fracture zone embedded deep within the Indo-Australian plate rather than slippage at the plate interface. "What we're looking at is probably a vestigial crack left over from some distant spreading centre," says McCloskey.
So, what kind of damage will the tsunami-triggering earthquake that the geologists have been predicting near Padang inflict? McCloskey has built computer models of over 125 scenarios in which shallow, powerful earthquakes at the interface off Padang jolt the sea floor, triggering tsunamis. In most, devastating tsunamis are generated. They will reach the city about 30 minutes after the earthquake hits.
His simulations suggest that 25 per cent of tsunamis would be over 5 metres tall as they reached the coast; the highest waves would be 12 metres tall. "In reality, of course, waves will gather height and become more turbulent as they power inland, which means they could be far higher over the city," says McCloskey.
If the people of Padang are well prepared, then most should survive, says McCloskey. Within 30 minutes, the young and the fit should be able to reach the 10-metre elevation contour that rises 2 kilometres back from the coast, he says, which would at least protect them from waves lower than 10 metres.
However, over 100,000 people – a seventh of the city's population – are blocked from running directly to higher ground by the barbed wire-laced, 10-metre-high walls of a huge military airport.
"Padang needs to build a tunnel under that airport, because if they don't these poor people will have to run parallel to the coast for several hundred metres while the tsunami is coming at them," says McCloskey. So far, no steps have been taken to build such an exit route. "Sometimes you despair," he says.
Source : Journal references: Earth and Planetary Science Letters, DOI: 10.1016/j.epsl.2007.09.034; Nature, DOI: 10.1038/nature07572