Showing posts with label Science and Environment. Show all posts

Tuesday, 20 May 2014

Water goes 'missing' with snow loss

By Jonathan AmosScience correspondent, BBC News

Mt Shasta, California, in December 2006. Snow-fed water resources are critically important to the western USA

Natural '"water towers" - places that hold and release water for society

A new study finds that if temperatures rise and more precipitation falls as rain rather than snow, it will reduce the total amount of water in rivers.

It is a surprising observation. One might expect the timing of water flow to change but not the overall volume.

But this is precisely what scientists discovered when they examined the histories of 420 catchment basins in the US spanning the period 1948-2001.

The researchers report their work in the journal Nature Climate Change.

The study compares places of similar climate and precipitation, but with differing fractions of that precipitation falling as snow and as rain.

And it seems there is a significant difference in total streamflow if the fraction shifts from snow to rain.

"At first we thought there could be all kinds of explanations for this, so we better dig a bit deeper and make sure that this difference between places wasn't being caused by something else," explained Dr Ross Woods from Bristol University, UK.

"We also checked out what happened at the same place between different years, and we found that the years with more snow also produced more streamflow than the years with less snow," he told BBC News.

Frozen ground

The team is now working through a number of possible explanations.

One idea is that the ground is also changing in response to temperature.

Colder conditions will lead to frozen ground, meaning when the snows do melt the water can run direct into streams and rivers.

In contrast, with warmer conditions, more water can be held in the ground for longer, to be later evaporated or transpired by plants. Less of the overall volume of water would then make it to streams and rivers.

"This issue is important because quite a lot of the snow at the moment is in the places we call the 'water towers' - the places that provide water to the great bulk of society," said Dr Woods.

"If the amount of water in the river on average goes down then those people find themselves under more pressure. Irrigation systems or hydropower systems or municipal water supply systems - the total amount of water available to those systems would be less.

"Those communities or systems would need then to adapt to that - to find a way to get by with less water, or else find alternative water sources."

Of course, under a generally warming climate, the overall patterns of precipitation are likely to change as well, with some locations receiving perhaps significantly more or less precipitation, irrespective of the fraction that is falling as snow or as rain.

The effect observed in this study may not therefore have too much relevance in some locations if their total water balance is rising. But in other, currently snowy places where overall precipitation is declining as well, the effect could compound problems.

The team hopes in future work to tease out the mechanisms involved.

Lead author Wouter Berghuijs said: "Hydrologists can take a large number of measurements at an individual site where they can determine for example what part of the flow in the river is due to a recent precipitation event and what part is due to ground water, by taking isotopic measurements of the stream.

"So, by going into great detail at individual places, it would be possible to understand the small-scale processes that underlie the behaviour that we observe," the researcher from Delft University of Technology, The Netherlands, told BBC News.

Headwaters of Tsitika River watershed on Northern Vancouver Island, British Columbia, December 2005. Temperature increases will affect the hydrological system in particular in rain/snow transition zones.

It is possible that ground conditions are playing an important role

Study: UK cities becoming mosquito-friendly habitats

By Mark KinverEnvironment reporter, BBC News

Close -up image of a male mosquito (Image: Science Photo Library)

A greater abundance of mosquitoes that act as vectors of human diseases are living in close proximity to people's homes

Changes to UK urban areas provide habitats for mosquitoes, including species known to spread malaria and West Nile virus, a study suggests.

Warmer ambient temperatures and more water containers in gardens are bringing mosquitoes into closer contact with people, say scientists.

UK mosquitoes are human disease-free but the team says more of the insects breeding in urban areas increases the chances of a potential outbreak.

The findings appear in Plos One.

Co-author Amanda Callaghan, an associate professor at the University of Reading's School of Biological Sciences, explained that the study aimed to collect data to see if there was a difference in abundance and diversity of mosquitoes in rural and urban locations.

"We knew that there was an urban heat island effect, and changes in temperature have been known to cause changes in mosquito behaviour and - in some regions, such as southern Europe - diseases have crept into these countries because mosquitoes have changed their behaviour," she said.

Habitat boom

Writing in their paper, Dr Callaghan and colleague Susannah Townroe observed: "Within the UK, [water butts - a container for rainwater] are becoming increasingly common in residential gardens.

"A severe drought and subsequent hosepipe ban in the spring of 2012 across southern and eastern England led to reports of hugely inflated sales of water butt containers," they added.

The number of water containers continues to grow as households look to save money and water

"Water butts collect rain from roof guttering along with vegetation, animal detritus... providing both a habitat and food resource for mosquito larvae."

They explained that while individual containers were relatively small, when all the water butts in the area were combined, it represented a "large area of habitat" for breeding mosquitoes.

The authors added: "This, in combination with the [urban heat island] effect... may favour mosquito larval production in urban habitats."

In order to test this idea, the researchers placed water containers in a number of urban and rural residential gardens.

"We found fewer species of mosquitoes in urban environments compared with rural environments, but the species that were there were much more abundant," Dr Callaghan told BBC News.

"The one that was most abundant is calledCulex pipiens, and in other countries C. pipienscarry diseases such as West Nile Virus."

The other species of mosquito that the researchers found in the study's water containers was Anopheles plumbeus, which has been shown to be a "reasonably good vector of malaria".

Dr Callaghan said: "The main finding is that these mosquitoes are right next to people's houses and the Anopheles mosquito we found is a human-biting species and it can transmit malaria.

"Therefore, if someone comes back from their holiday with malaria and they get bitten, it could be transmitted to another person - and that is how you get outbreaks.

"The chances of there being a malaria epidemic in this country at present are relatively low because there has not been secondary malaria here since the 1950s."

Secondary malaria refers to someone catching malaria from another person who has also been bitten by a mosquito.

"I am not saying we are all going to get diseases because we have vectors here, but it is worth keeping an eye on."

Changing behaviour

More than 30 different mosquito species have been recorded in the UK, most of which are resident all year round.

"In rural areas you get more types of mosquito - there are lots of different types of habitats and different species of mosquito like different types of habitat - some of them will favour ditches, others will favour ponds or tree holes etc," Dr Callaghan explained.

"Whereas if you go into an urban environment, you do not have a lot of those habitats so you get a different picture of what species can survive in this environment.

"The Culex pipiens is a well-known urban mosquito, but the Anopheles plumbeus is normally considered to be a tree-dwelling species. But it is changing its habitats from breeding in tree-holes to breeding in man-made water containers.

"This is concerning considering that it is a vector of malaria."

Dr Callaghan said there were thousands of cases of malaria in the UK each year, mostly as a result of people returning from areas of the world where malaria was present, but people were usually quickly treated.

"If malaria is not in your blood for any length of time, the chances of you being bitten and transmitting it are quite low," she said.

"But if more people come back with malaria and there are more mosquitoes that can transmit malaria living by you then that chance increases."

Monday, 19 May 2014

Baby mammoth goes on display in UK By Sarah White

Baby mammoth goes on display in UK

By Sarah WhiteBBC News, at the Natural History Museum

The 42,000-year old carcass was discovered by a reindeer herder

A perfectly preserved baby mammoth which died 42,000 years ago has been unveiled at the Natural History Museum in London.

Named Lyuba by the Siberian deer herder who discovered her in 2007, the specimen is 130cm tall and weighs 50kg.

Palaeontologist Prof Adrian Lister, described seeing her for the first time as an "incredible experience".

Transported in a box that was opened on Monday, the juvenile female mammoth looked completely intact.

Prof Lister pointed out the small milk tusks that are barely visible, the almost flattened shape of the trunk designed to drink water from snow and a small layer of fat on top of the head which would have kept her warm in the permafrost of north-west Siberia.

Lyuba was found to have clay in her trunk, leading scientists to believe she suffocated on it whilst getting water. She is believed to have been discovered after her snowy grave thawed out during the spring and her remains washed up on a river bank.

The animal looked more like her distant elephant family relatives with wrinkled, leathery skin, as the hair which would have covered her warm in life had eroded away, leaving just a few tufts.

Her only defect was the tail which has been gnawed off by animals.

Her body looks slightly deflated, which Prof Lister explains is from her effectively being mummified under the weight of all that ice for so long. Traces of the blue, powdery mineral vivianite, which is commonly found on fossils, can be seen on her body.

Professor Lister said: "To see a three-dimensional mammoth in the flesh is absolutely extraordinary.

"To be eyeball to eyeball with a creature from the Ice Age which is so perfectly preserved and lifelike, looking like she is lying down and might walk away at any minute, is really moving. I have to pinch myself to think she died 42,000 years ago.

"It's wonderful to be able to share this with the public at the museum when she's never been outside of Russia and Asia before. It's really exciting and I'm sure others will be moved by seeing her."

Lyuba was named after the deer herder Yuri Khudi's wife (the name also means love in Russian). She was discovered by the Yuribei River, in the Yamal-Nenets district. Even her internal organs are intact.

Scientists regard the specimen as the most fully preserved mammoth ever found.

Mammoths first appeared in the Pliocene Epoch, some 4.8 million years ago. Climate change, overkill by human hunters, or a combination of both are among the explanations for their eventual disappearance about 5,000 years ago.

Lyuba, normally on display at the Yamal-Nenets Regional Museum-Exhibition Complex, will be on show at the Natural History Museum from Friday 23 May until 7 September.

Survey suggests support for fracking in UK falls below 50%

$An anti-fracking banner$ Protests in 2013 have been cited as the moment public opinion about fracking changed

The number of people in favour of fracking for shale gas in the UK has fallen below 50%, a new poll suggests.

Just 49.8% were in favour of shale gas extraction when researchers from the University of Nottingham asked 3,657 people earlier this month.

This is the lowest number in support of fracking since the university started its poll on the issue in 2012.

The latest results found 31.4% were against fracking, while 18.4% were undecided.

"The May 2014 survey confirms that the turn against fracking for shale gas in the UK has deepened," says the report.

And it cites the anti-fracking protests which took place in the village of Balcombe in West Sussex in 2013 as a tipping point when the tide of public opinion towards shale gas extraction began to shift.

Since those protests the number of people against fracking has been steadily rising, it says.

$fracking graphic$

Tory peer Lord Howell of Guildford - who apologised last year after saying that fracking should take place in the North East because it was "desolate" - recently spoke about the issue again, and said the Conservative Party could lose votes by pursuing plans to frack.

But the poll suggested that this may not happen as it found support for fracking higher among Tory and UKIP voters - around 68% - while Labour and Lib Dem supporters were generally much less in favour.

The survey also found that an increasing number of people were better educated about the technology and processes behind shale gas extraction.

Fracking is the process of drilling down into the earth before a high-pressure water mixture is directed at the rock to release the gas inside. Water, sand and chemicals are injected into the rock at high pressure which allows the gas to flow out to the head of the well.

UK overseas wildlife 'needs protection'

By Alasdair CrossProducer, Costing the Earth

The UK's Overseas Territories host hundreds of globally threatened species, like this curlytail lizard

If you want to see the Giant Earwig of St Helena you may already be too late.

Fancy sniffing a pretty yellow Arlihau flower in the wild? You'll have to hurry down to Pitcairn Island as there are only six plants left.

The common thread linking these endangered species is that they are residents of UK Overseas Territories.

The Royal Society for the Protection of Birds has reported that 94% of unique British species live outside the UK - and some urgently need protection.

The RSPB report concerns 14 territories - relics of empire scattered from the South Pacific to the Mediterranean.

Prime Minister David Cameron has said that the Overseas Territories provide, "an important opportunity to set world standards in our stewardship of the extraordinary natural environments we have inherited".

With the report showing that 85% of our critically endangered species live in these territories, the RSPB is asking for increased spending to meet the Prime Minister's ambitions.

The Turks and Caicos Islands, 250km (150 miles) to the east of Cuba, are home to unique species such as the Barking Gecko, the Turks and Caicos Rock Iguana and the Pygmy Boa Constrictor.

But there is no statutory protection for native creatures there, and intense pressure on their habitat as the tourist industry expands.

There are plans for a dolphinarium on the island of Grand Turk and proposals to build a freight shipping port, marina and cruise ship terminal on East Caicos. It's one of the largest uninhabited islands in the Caribbean with some of the region's best preserved coral reefs and turtle nesting beaches.

The head of the islands' Department of Environment and Maritime Affairs, Kathleen Wood, fears that "this kind of project cannot be done sensitively. You would have to dredge through an incredible amount of reef".

Turks and Caicos premier Rufus Ewing is more enthusiastic, accepting that some of the pristine environment will be damaged. He told BBC Radio Four's Costing the Earth programme: "There are some things that sometimes we may have to sacrifice. It is an area we can use to boost our economy, to boost our development. "

Other risks to the species of Turks and Caicos come from further afield. Endangered Queen Conch and Spiny Lobster are taken by scuba-diving poachers whilst the scrub forests are being ravaged by fires burnt by illegal immigrants from Haiti. Mature trees are felled and burnt to make charcoal for their cooking stoves.

Should Britain be doing more to protect the environment of Turks and Caicos and the other territories, as the RSPB is demanding? Foreign Office minister Mark Simmonds says that the UK funds specific conservation projects and helps train local staff - but, ultimately, "it is the responsibility of the territory governments to deliver environment protection and the maintenance of their bio-diversity".

But back in Turks and Caicos, Ethlyn Gibbs-Williams of the local National Trust would like the UK to flex its muscles. The local emphasis on economic development needs to be tempered, she says: "We would like to see more support from the British government ensuring that we have strong environmental laws".

Costing the Earth reports from the Turks and Caicos Islands on BBC Radio Four at 3.30pm on Tuesday 20th May.

£10m Longitude Prize announced

Longitude Prize launched with £10m awaiting winner

John Harrison's H4 "pocket watch" was the winner of the original Longitude Prize

The competition idea is based on the 1714 Longitude Prize, which was won by John Harrison. His clocks enabled sailors to pinpoint their position at sea for the first time.A £10m prize has been launched to solve one of the greatest scientific problems facing the world today.

In an updated version, the public will be asked to choose a new challenge.

Six potential categories have been announced, ranging from healthcare to the environment.

After a special 50th anniversary edition of the BBC science series Horizon on Thursday, the public will be able to cast their vote on the issue that they would most like to see tackled.

Geoff Mulgan, chief executive of the charity Nesta, which is looking after the prize, said: "If you want to solve a scientific problem, one method is to go to top universities and top scientists and ask them to solve it.

It took decades of work before John Harrison was finally awarded the prize

"But over the years, and this was something pioneered by the Longitude Prize in the 18th Century, it's often better to open it up to anyone to come up with a solution."

The original £20,000 prize was set by the British government to solve the most vexing issue of the 18th Century: how to determine a ship's longitude at sea.

For sailors to pinpoint their position on the waves, they required two clocks: one that was set each day, using the the height of the sun in the sky, and another that kept the time back at port.

The problem with the latter was that the pitch and roll of the oceans, and the humidity and temperature changes at sea would damage the delicate mechanisms of a timepiece.

But Mr Harrison, a clockmaker from Yorkshire, created a chronometer that overcame these problems.

It took several prototypes and decades of battling with the scientific elite before he was finally deemed the winner. His work revolutionised navigation and saved countless lives.

Now, 300 years later, a new challenge is being launched.

“Start Quote

We're going to set a very precise measurement of what will count as eligibility for winning the prize”

Geoff MulganNesta

Nesta and the government-funded Technology Strategy Board are offering £10m for a solution to the biggest scientific problem of our time.

The categories from which "the problem" will be chosen was announced on Monday. These themes have been been selected by a Longitude Committee, chaired by the English Astronomer Royal, Prof Sir Martin Rees, after widespread consultation with experts across various fields. They are:

Flight - How can we fly without damaging the environment?
Food - How can we ensure everyone has nutritious sustainable food?
Antibiotics - How can we prevent the rise of resistance to antibiotics?
Paralysis - How can we restore movement to those with paralysis?
Water - How can we ensure everyone has access to safe and clean water?
Dementia - How can we help people with dementia live independently for longer?

Standing next to Harrison's H4 timekeeper at the launch of the prize, the BBC's director-general Tony Hall said: "What's really exciting about the Longitude Prize 300 years on in 2014 is that there might be another modern-day John Harrison somewhere out there - someone who will be inspired to change our world fundamentally, and they may not even know that they're a scientist."

Comparing the modern prize to its predecessor, Prof Sir Martin Rees, chair of the Longitude Committee and English Astronomer Royal, commented: "There's no manifest number one problem as there was in the 18th Century. Rather there are many broad societal problems demanding fresh thinking.

"There's a pressing need also for the UK to channel more brain power into innovation, jump-start new technologies and enthuse young people."

Each category will be examined in the Horizon programme to be broadcast on BBC Two at 2100 on Thursday. After that, a public vote will be opened, with a favoured theme to be announced on 25 June.

At the prize launch held at Broadcasting House in London, the six challenges were outlined by Horizon presenters.

Prof Brian Cox: Public vote on Longitude Prize is invaluable

A&E doctor Saleyha Ahsan is presenting the segment on providing freedom of movement for people with paralysis. She demonstrated the potential for her challenge with the help of Sophie Morgan, who has a spinal cord injury.

Using a robotic exoskeleton called Rex, Ms Morgan was able to stand up on stage.

Ms Morgan, who has been using Rex for one month, told the audience: "Having been sat down all the time, it is literally and metaphorically a perspective shifter... I've been psychologically affected by talking to people at eye level and there are health benefits. Already, I'm sleeping better, feeling better, my body is getting better and the pain is gone."

BBC TV presenter Michael Mosley demonstrated his challenge with the help of insects, a source of protein that could offer one way to fight world hunger. He suggested insects could be turned into a kind of flour to make them more palatable to consumers.

After the result of the vote is announced, experts will then convene to refine the details of the challenge, with anyone from around the world able to submit their solution.

Mr Mulgan said: "We're going to set a very precise measurement of what will count as eligibility for winning the prize.

"The prize will only be awarded when someone can demonstrate that their invention actually meets those criteria."

He said that it could be several years before a winner is decided.

David Rowan, the editor of Wired Magazine, is on the committee. He said: "The brilliant thing about the Longitude Prize is that we don't know where the answer's going to come from.

"The crowd is smarter than any of us on the committee. And the beautiful thing about the internet is that by connecting people together, two plus two is five or five hundred. People come together in all sorts of extraordinary and unpredictable ways to solve problems and we want to see where this goes. Surprise us!"

And Roger Highfield, the renowned science writer and director of external affairs at London's Science Museum, commented: "We've got challenges like global climate change, like the growth in the global population, pressure on food supplies, and pressure on water supplies. I think actually this is a very opportune moment for challenges across a range of fronts. So, the Longitude Prize has just come in the nick of time."

Antarctica's ice losses double

Esa's Cryosat mission sees Antarctic ice losses double

By Jonathan AmosScience correspondent, BBC News

Antarctica is now losing about 160 billion tonnes of ice a year to the ocean - twice as much as when the continent was last surveyed.

The new assessment comes from Europe's Cryosat spacecraft, which has a radar instrument specifically designed to measure the shape of the ice sheet.

The melt loss from the White Continent is sufficient to push up global sea levels by around 0.43mm per year.

Scientists report the data in the journal Geophysical Research Letters.

The new study incorporates three years of measurements from 2010 to 2013, and updates a synthesis of observations made by other satellites over the period 2005 to 2010.

Cryosat has been using its altimeter to trace changes in the height of the ice sheet - as it gains mass through snowfall, and loses mass through melting.

'Big deal'

The study authors divide the continent into three sectors - the West Antarctic, the East Antarctic, and the Antarctic Peninsula, which is the long finger of land reaching up to South America.

Overall, Cryosat finds all three regions to be losing ice, with the average elevation of the full ice sheet falling annually by almost 2cm.

Cryosat's double antenna configuration allows it to map slopes very effectively

In the three sectors, this equates to losses of 134 billion tonnes, 3 billion tonnes, and 23 billion tonnes of ice per year, respectively.

The East had been gaining ice in the previous study period, boosted by some exceptional snowfall, but it is now seen as broadly static in the new survey.

As expected, it is the western ice sheet that dominates the reductions.

Scientists have long considered it to be the most vulnerable to melting.

It has an area, called the Amundsen Sea Embayment, where six huge glaciers are currently undergoing a rapid retreat - all of them being eroded by the influx of warm ocean waters that scientists say are being drawn towards the continent by stronger winds whipped up by a changing climate.

About 90% of the mass loss from the West Antarctic Ice Sheet is going from just these few ice streams.

At one of them - Smith Glacier - Crysosat sees the surface lowering by 9m per year.

Some western ice streams such as Pine Island Glacier are retreating and thinning rapidly

"CryoSat has given us a new understanding of how Antarctica has changed over the last three years and allowed us to survey almost the entire continent," explained lead author Dr Malcolm McMillan from the NERC Centre for Polar Observation and Modelling at Leeds University, UK.

"We find that ice losses continue to be most pronounced in West Antarctica, along the fast-flowing ice streams that drain into the Amundsen Sea. In East Antarctica, the ice sheet remained roughly in balance, with no net loss or gain over the three-year period," he told BBC News.

Cryosat was launched by the European Space Agency in 2010 on a dedicated quest to measure changes at the poles, and was given a novel radar system for the purpose.

It has two antennas slightly offset from each other. This enables the instrument to detect not just the height of the ice sheet but the shape of its slopes and ridges.

This makes Cryosat much more sensitive to details at the steep edges of the ice sheet - the locations where thinning is most pronounced.

It also allows the satellite to better detect what is going on in the peninsula region of the continent where the climate has warmed rapidly over the past 50 years.

"The peninsula is extremely rugged and previous satellite altimeters have always struggled to see its narrow glaciers. With Cryosat, we get remarkable coverage - better than anything that's been achieved before," said Prof Andy Shepherd, also of Leeds University.

Future change

The GRL paper follows hard on the heels of two studies that have made a specific assessment of the future prospects for the Amundsen Sea Embayment.

One of these reports concluded that the area's glaciers were now in an irreversible retreat.

The other paper, considering one of the glaciers in detail, suggested the reversal process could take several hundred years to be completed.

A loss of all the ice in the six glaciers would add about 1.2m to global sea level.

This is still a small fraction of the total sea-level potential of Antarctica, which holds something like 26.5 million cubic km ice (or 58m of sea-level rise equivalent). But the continent has been largely insulated from some of the warming influences taking place elsewhere in the world and it is important, say scientists, to keep a check on any changes that are occurring, and the speed with which they are happening.

Prof Duncan Wingham proposed the Cryosat mission and is its principal investigator. He told BBC News: "We lack the capability to predict accurately how the Amundsen ice streams will behave in future.

"Equally, a continuation or acceleration of their behaviour has serious implications for sea level rise. This makes essential their continued observation, by Cryosat and its successors."

And Prof David Vaughan of the British Antarctic Survey was not involved in the Cryosat survey. He commented: "The increasing contribution of Antarctica to sea-level rise is a global issue, and we need to use every technique available to understand where and how much ice is being lost.

"Through some very clever technical improvements, McMillan and his colleagues have produced the best maps of Antarctic ice loss we have ever had. Prediction of the rate of future global sea-level rise must be begin with a thorough understanding of current changes in the ice sheets - this study puts us exactly where we need to be."

Cryosat's radar copes better with the rugged terrain of the Antarctic Peninsula

Friday, 16 May 2014

'Biggest dinosaur ever' discovered

By James MorganScience reporter, BBC News

Fossilised bones of dinosaur believed to be the largest creature ever to walk the Earth has been unearthed in Argentina, palaeontologists say.

Based on its huge thigh bones, it was 40m (130ft) long and 20m (65ft) tall.

Weighing in at 77 tonnes, it was as heavy as 14 African elephants, and seven tonnes heavier than the previous record holder, Argentinosaurus.

Scientists believe it is a new species of titanosaur - an enormous herbivore dating from the Late Cretaceous period.

A local farm worker first stumbled on the remains in the desert near La Flecha, about 250km (135 miles) west of Trelew, Patagonia.

Dr Diego Pol explains how the weight of the dinosaur was calculated

The fossils were then excavated by a team of palaeontologists from the Museum of Palaeontology Egidio Feruglio, led by Dr Jose Luis Carballido and Dr Diego Pol.

They unearthed the partial skeletons of seven individuals - about 150 bones in total - all in "remarkable condition".

A film crew from the BBC Natural History Unit was there to capture the moment the scientists realised exactly how big their discovery was.

By measuring the length and circumference of the largest femur (thigh bone), they calculated the animal weighed 77 tonnes.

"Given the size of these bones, which surpass any of the previously known giant animals, the new dinosaur is the largest animal known that walked on Earth," the researchers told BBC News.

"Its length, from its head to the tip of its tail, was 40m.

"Standing with its neck up, it was about 20m high - equal to a seven-storey building."

The new dinosaur is a type of sauropod similar to Argentinosaurus, illustrated here

This giant herbivore lived in the forests of Patagonia between 95 and 100 million years ago, based on the age of the rocks in which its bones were found.

But despite its magnitude, it does not yet have a name.

"It will be named describing its magnificence and in honour to both the region and the farm owners who alerted us about the discovery," the researchers said.

There have been many previous contenders for the title "world's biggest dinosaur".

The most recent pretender to the throne wasArgentinosaurus, a similar type of sauropod, also discovered in Patagonia.

Originally thought to weigh in at 100 tonnes, it was later revised down to about 70 tonnes - just under the 77 tonnes that this new sauropod is thought to have weighed.

The picture is muddied by the various complicated methods for estimating size and weight, based on skeletons that are usually incomplete.

Argentinosaurus was estimated from only a few bones. But the researchers here had dozens to work with, making them more confident that they really have found "the big one".

Dr Paul Barrett, a dinosaur expert from London's Natural History Museum, agreed the new species is "a genuinely big critter. But there are a number of similarly sized big sauropod thigh bones out there," he cautioned.

"Without knowing more about this current find it's difficult to be sure. One problem with assessing the weight of both Argentinosaurusand this new discovery is that they're both based on very fragmentary specimens - no complete skeleton is known, which means the animal's proportions and overall shape are conjectural.

"Moreover, several different methods exist for calculating dinosaur weight (some based on overall volume, some on various limb bone measurements) and these don't always agree with each other, with large measures of uncertainty.

"So it's interesting to hear another really huge sauropod has been discovered, but ideally we'd need much more material of these supersized animals to determine just how big they really got."