Monday, 22 May 2017

Giant 19.4m wave recorded in Southern Ocean


A 19.4m wave has been detected south of New Zealand - and the company that recorded the behemoth believes monsters reaching over 20m were probably created by the same storm.

In a collaboration with the New Zealand Defence Force, science-based consultancy MetOcean Solutions recently moored the high-tech instrument in the Southern Ocean off Campbell Island, nearly halfway between the South Island and Antarctica.

Persistent westerly winds and an unlimited area for waves to build combine to make Southern Ocean waves among the biggest in the world.

Yesterday, MetOcean Solutions confirmed it had picked up a 19.4m wave - close to the highest wave ever recorded, which was detected rolling through the North Atlantic Ocean between Iceland and the UK last year.

It's expected the buoy may be ultimately register waves 25m high - the height of an eight-storey building - as it continues its real-time readings fixed in 150m of water.

But MetOcean Solutions senior oceanographer Dr Tom Durrant was nonetheless thrilled with Saturday's detection.

"This is one of the largest waves recorded in the Southern Hemisphere," he said.
"This is the world's southernmost wave buoy moored in the open ocean, and we are excited to put it to the test in large seas."

The company's managing director, Peter McComb, told the Herald that waves larger than 20m likely also occurred between the sampling times, which took place for 20 minutes every three hours.

http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=11860343

Friday, 19 May 2017

Thanks to global warming, Antarctica is starting to turn green


Researchers in Antarctica have discovered rapidly growing banks of mosses on the ice continent's northern peninsula, providing striking evidence of climate change in the coldest and most remote parts of the planet.

Amid the warming of the past 50 years, the scientists found two species of moss undergoing the equivalent of growth spurts, with mosses that once grew less than 1mm a year, now growing more than 3mm a year on average.

"People will think of Antarctica quite rightly as a very icy place, but our work shows that parts of it are green, and are likely to be getting greener," said Matthew Amesbury, a researcher with the University of Exeter in the UK and lead author of the study.

"Even these relatively remote ecosystems, that people might think are relatively untouched by human kind, are showing the effects of human-induced climate change."

The study was published Thursday in Current Biology, by Amesbury and colleagues with Cambridge University, the British Antarctic Survey, and the University of Durham.

Less than 1 per cent of present-day Antarctica features plant life. But in parts of the peninsula, Antarctic mosses grow on frozen ground that partly thaws in the summer - when only about the first 30cm of soil thaws.

The surface mosses build up a thin layer in the summer, then freeze over in winter. As layer builds on top of layer, older mosses subside below the frozen ground, where they are remarkably well preserved because of the temperatures.

Amesbury said that made them "a record of changes over time".

http://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=11858956

Wednesday, 17 May 2017

Orcas are slaughtering sharks for their livers in precise attacks


Great white sharks are being killed in bizarre fashion off the coast of South Africa as carcasses have been found washed up with only their livers missing.

Killer whales are believed to be responsible for the strange predatory pattern, with one expert noting that the organs were removed with "surgical precision".

At least three liver-less white shark carcasses have washed up near the popular tourist town Gansbaai, South Africa, so far in an unprecedented set of killings.

Experts suggest that local killer whales have developed an appetite for squalene - an organic chemical compound found in abundance in shark liver oil.

"Obviously this is a very sad time for us all," Alison Towner, a biologist with the Dyer Island Conservation Trust, wrote in a Facebook post after the third carcass was discovered near Gansbaai.

"Nature can be so cruel and the dexterity these enormous animals are capable of is mind blowing... almost surgical precision as they remove the squalene-rich liver of the white sharks and dump their carcass."

Gansbaai is widely considered one of the best regions in the world for shark diving.

Sharks generate millions in tourist revenue for the town, but the killer whales' spree appears to have driven many of the sharks away.

Local shark diving tour companies have complained that their trips are coming up empty.

http://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=11855378

Monday, 15 May 2017

Climate cycles that could mean we're about to get even hotter


El Nino, and its sister La Nina, have long been one of the key drivers of Australia's weather.

But environmental scientists now suspect they could be little more than the climactic equivalents of cheeky kids at the family barbecue. Instead, a "kindly aunty" and "cranky uncle" could have a far more wide reaching effect on our climate.

With El Nino being the Spanish for "the boy" and La Nina "the girl" scientists have named these overarching systems El Tio meaning, "the uncle," and La Tia "the aunt".

And if the boy and the uncle join forces, things may be about to get hairy. At the very least, you may want to slap on some more sunscreen, reports News.com.au.

Dr Benjamin Henly, a climate scientist at the University of Melbourne, told news.com.au a prolonged La Tia may have "lulled us into a false sense of security" that global warming had slowed when the reality is climate change could be on the verge of accelerating.

That could spell disaster for the 2015 Paris Climate Agreement which aimed to keep the world's average annual temperatures to 1.5C below pre industrial levels.

The El Nino Southern Oscillation (ENSO) is a climate cycle operating in the Pacific.

A negative ENSO phase, commonly known as an El Nino, sends hotter weather to Australia and can lead to less rain, sustained droughts and weather extremes. A positive ENSO, La Nina, sees cooler conditions and more rain.

Seven out of the 10 driest Australian summers have coincided with El Nino, including 2016 which was the hottest year on record.

http://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=11855216

Saturday, 13 May 2017

Oceans are at the 'edge' of losing all oxygen


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The world's oceans close to being starved of oxygen - and even that could lead to mass sea life extinction which could last a million years.

University of Exeter scientists fear the modern ocean is 'on the edge of anoxia' - when the oceans are depleted of oxygen.

And while this dramatic drop in oceanic oxygen comes to a natural end, it takes about a million years,

Studying what happened during the Jurassic period, they found the drop in oxygen causes more organic carbon to be buried in sediment on the ocean floor.

This eventually leads to rising oxygen in the atmosphere which ultimately re-oxygenates the ocean. But it took a million years to get the balance right again.
 
Lead researcher PhD student Sarah Baker said it was now 'critical' for modern humans to limit carbon emissions to prevent this.

She said: 'Once you get into a major event like anoxia, it takes a long time for the Earth's system to rebalance.

'This shows the vital importance of limiting disruption to the carbon cycle to regulate the Earth system and keep it within habitable bounds.'

The researchers studied the Toarcian Oceanic Anoxic Event, which took place 183 million years ago.

Tuesday, 9 May 2017

Alaska's tundra is 'filling the atmosphere with carbon dioxide, worsening climate change'


Even as the Trump Administration weighs withdrawing the United States from the Paris climate agreement, a new scientific paper has documented growing fluxes of greenhouse gases streaming into the air from the Alaskan tundra, a long-feared occurrence that could worsen climate change.

The new study, published in the Proceedings of the National Academy of Sciences, suggests that frozen northern soils - often called permafrost - are unleashing an increasing amount of carbon dioxide into the air as they thaw in summer or subsequently fail to refreeze as they once did, particularly in late fall and early winter.

"Over a large area, we're seeing a substantial increase in the amount of CO2 that's coming out in the [autumn]," said Roisin Commane, a Harvard atmospheric scientist who is the lead author of the study. The research was published by 19 authors from a variety of institutions, including Nasa's Jet Propulsion Laboratory and the National Oceanic and Atmospheric Administration.

The study, based on aircraft measurements of carbon dioxide and methane and tower measurements from Barrow, Alaska, found that from 2012 to the end of 2014, the state emitted the equivalent of 220 million tonnes of carbon dioxide gas into the atmosphere from biological sources (the figure excludes fossil fuel burning and wildfires). That's an amount comparable to all the emissions from the US commercial sector in a single year.

The chief reason for the greater CO2 release was that as Alaska has warmed up, emissions from once frozen tundra in winter are increasing - presumably because the ground is not refreezing as quickly.
"The soils are warmer deeper, and as they freeze in the [autumn], the temperature of every soil depth has to come to zero before they hard freeze," Commane said. "The temperature has to come to zero and equilibrate, for the soils to freeze hard through. And through that whole period you have emissions because the microbe are active."

In particular, the research found that since 1975, there has been a 73.4 per cent increase in the amount of carbon lost from the Alaskan tundra in the months of October through December as the climate warmed steadily.

http://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=11852064

Friday, 5 May 2017

New crack in one of Antarctica's biggest ice shelves could mean a major break is near


Another branch has appeared in a huge crack on one of Antarctica's largest ice shelves, and scientists fear it's only a matter of time before a massive chunk -- potentially containing up to 5200sq km of ice -- breaks away. If this happens, the ice shelf may become increasingly unstable and could even fall apart.
 
Scientists have been closely monitoring the Larsen C ice shelf, located on the east coast of the Antarctic Peninsula, where a large rift in the ice -- now about 180km long -- has been advancing in rapid bursts in recent years. Between the beginning of December and the middle of January alone, the crack lengthened by about 27km. And since 2011, it has grown by about 80km.

Over the past few months, scientists have noticed that the crack has stopped extending in length but has continued to widen at a rate of more than a metre a day. It's already more than 300m wide.

And now, scientists have noticed a worrying development: A new branch has split off from the main rift, about 10km below the tip of the original crack, and has splintered off in the direction of the ocean. The new branch is about 15km long. Altogether, only about 20km of ice now stands in the way of the whole chunk splitting off into the sea.

Researchers from Project Midas, a British-based Antarctic research project based at Swansea University and Aberystwyth University, observed the new crack in satellite images on May 1.
The biggest concern is not whether the chunk will break off -- that seems to be inevitable at this point -- but what will happen after it does. The break will sweep away about 10 per cent of the ice shelf's total area, and scientists have previously speculated that the shelf will become increasingly unstable after this point.

"We have previously shown that the new configuration will be less stable than it was before the rift, and that Larsen C may eventually follow the example of its neighbour Larsen B, which disintegrated in 2002 following a similar rift-induced calving event," Swansea University professor Adrian Luckman, a leader at Project Midas, said in a statement.


http://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=11850335