While atmospheric radiation was detected on the US west coast within days of the incident, the radioactive particles in the ocean plume take considerably longer to travel the same distance.

In the paper, researchers from the Centre of Excellence for Climate System Science and others used a range of ocean simulations to track the path of the radiation from the Fukushima incident.

The models identified where it would likely travel through the world’s oceans for the next 10 years.

“Observers on the west coast of the United States will be able to see a measurable increase in radioactive material three years after the event,” said one of the paper’s authors, Dr Erik van Sebille.

“However, people on those coastlines should not be concerned as the concentration of radioactive material quickly drops below World Health Organisation safety levels as soon as it leaves Japanese waters.”

Two energetic currents off the Japanese coast — the Kuroshio Current and the Kurushio Extension — are primarily responsible for accelerating the dilution of the radioactive material, taking it well below WHO safety levels within four months.

Eddies and giant whirlpools — some tens of kilometres wide — and other currents in the open ocean continue this dilution process and direct the radioactive particles to different areas along the US west coast.

“Although some uncertainties remain around the total amount released and the likely concentrations that would be observed, we have shown unambiguously that the contact with the north-west American coasts will not be identical everywhere,” said Dr. Vincent Rossi.

“Shelf waters north of 45°N will experience higher concentrations during a shorter period, when compared to the Californian coast. This late but prolonged exposure is due to the three-dimensional pathways of the plume. The plume will be forced down deeper into the ocean toward the subtropics before rising up again along the southern Californian shelf.”

Interestingly, the great majority of the radioactive material will stay in the North Pacific, with very little crossing south of the Equator in the first decade. Eventually over a number of decades, a measurable but otherwise harmless signature of the radiation will spread into other ocean basins, particularly the Indian and South Pacific oceans.

“Australia and other countries in the Southern Hemisphere will see little if any radioactive material in their coastal waters and certainly not at levels to cause concern,” Dr van Sebille said.

“For those interested in tracking the path of the radiation, we have developed a website (adrift.org.au) to help them.

“Using this website, members of the public can click on an area in the ocean and track the movement of the radiation or any other form of pollution on the ocean surface over the next 10 years.”

A team from the Department of Geography used declassified spy satellite imagery to create the first long-term record of changes in the terminus of outlet glaciers — where they meet the sea — along 5,400km of the East Antarctic Ice Sheet’s coastline. The imagery covered almost half a century from 1963 to 2012.

Using measurements from 175 glaciers, the researchers were able to show that the glaciers underwent rapid and synchronised periods of advance and retreat which coincided with cooling and warming.

The researchers said this suggested that large parts of the ice sheet, which reaches thicknesses of more than 4km, could be more susceptible to changes in air temperatures and sea-ice than was originally believed.

Current scientific opinion suggests that glaciers in East Antarctica are at less risk from climate change than areas such as Greenland or West Antarctica due to its extremely cold temperatures which can fall below minus 30°C at the coast, and much colder further inland.

But the Durham team said there was now an urgent need to understand the vulnerability of the East Antarctic Ice Sheet, which holds the vast majority of the world’s ice and enough to raise global sea levels by over 50m.

Dr Chris Stokes, in Durham’s Department of Geography, said: “We know that these large glaciers undergo cycles of advance and retreat that are triggered by large icebergs breaking off at the terminus, but this can happen independently from climate change.

“It was a big surprise therefore to see rapid and synchronous changes in advance and retreat, but it made perfect sense when we looked at the climate and sea-ice data.

“When it was warm and the sea-ice decreased, most glaciers retreated, but when it was cooler and the sea ice increased, the glaciers advanced.

“In many ways, these measurements of terminus change are like canaries in a mine — they don’t give us all the information we would like, but they are worth taking notice of.”

The researchers found that despite large fluctuations in terminus positions between glaciers — linked to their size — three significant patterns emerged:

• In the 1970s and 80s, temperatures were rising and most glaciers retreated;
• During the 1990s, temperatures decreased and most glaciers advanced;
• And the 2000s saw temperatures increase and then decrease, leading to a more even mix of retreat and advance.

Trends in temperature and glacier change were statistically significant along the East Antarctic Ice Sheet’s warmer Pacific Coast, but no significant changes were found along the much cooler Ross Sea Coast, which might be expected if climate is driving the changes, the Durham researchers said.

Dr Stokes said that the cause of the recent trends in air temperature and sea ice were difficult to unravel but were likely to reflect a combination of both natural variability and human impacts.

However, he added that the changes observed in glaciers in East Antarctica needed further investigation against the backdrop of likely increases in both atmospheric and ocean temperatures caused by climate change.

Dr Stokes said: “If the climate is going to warm in the future, our study shows that large parts of the margins of the East Antarctic Ice Sheet are vulnerable to the kinds of changes that are worrying us in Greenland and West Antarctica — acceleration, thinning and retreat.

“When temperatures warm in the air or ocean, glaciers respond by retreating and this can have knock-on effects further inland, where more and more ice is drawn-down towards the coast.

“We need to monitor their behaviour more closely and maybe reassess our rather conservative predictions of future ice sheet dynamics in East Antarctica.”

Aug. 28, 2013 by Sean Kilcarr in Trucks at Work

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Over the last three years, a collection of Swedish government agencies and private companies tested out a variety of truck fuels in combination with what’s been dubbed more “efficient” logistical networks to see whether such efforts could significantly reduce truck emission levels.

Working under the perhaps unsurprising name “Climate-Smart City Distribution” project, this 36-month effort involved 393 vehicles operating Gothenburg, Sweden, on a wide variety of fuels – biodiesel, biogas and dimethyl ether (DME), hybrid technology, and methane-diesel fuel – and resulted in a reported 30% average reduction in carbon dioxide (CO2) truck emissions; increasing in some cases from 65% to 84%, depending on the fuel and type of vehicle.

Here’s a breakdown: Of the 393 vehicles that participated in this project, some 48 are light gas-driven vehicles, 44 are heavy methane-diesel vehicles and four are heavy hybrid vehicles.

Lars Mårtensson, environmental director for Volvo Trucks, noted that in downtown Gothenburg, some 6,500 companies required daily goods distribution services. Thus he believes one of the results of this three-year project is the finding that with better coordination and more efficient utilization of existing vehicles, both congestion and emissions can be reduced even further.

“In order to fully exploit the available potential, it’s not enough for haulage companies to improve their logistics systems,” he explained. “It is equally important that transport purchasers become better at coordinating their purchases, and here there is a whole lot of room for improvement.”

Opening up bus lanes to distribution traffic and undertaking more transportation operations when there is less traffic on the roads are other examples of relatively simple measures that can deliver significant environmental benefits, Mårtensson said.

Yet he also stressed that most difficult challenge, however, was not to develop new fuels or new vehicle technology but to improve the efficiency of current transport operations.

“With more energy-efficient vehicles, fuels with a lower environmental impact and smarter logistics, it is possible to achieve significant improvements,” added Olof Persson, Volvo’s president and CEO.

“The problems are the same the world over,” he pointed out. “Populations are growing, along with the need for transport. This brings with it increasing environmental problems such as congestion, noise, poor air quality and climate impact.”

Yet Mårtensson believes this trend can be reversed. “The road ahead goes via closer cooperation between different actors and here we definitely have a role to play, both locally and globally,” he said.

The other critical factor here, of course, is whether fleets and their customers can save money by making such changes to both fuel and logistical patterns. That to my mind will be the key to make such efforts trult successful over the long term.

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