Truth Frequency Radio


Oct 17, 2012

October 17, 2012GEOLOGY – An extremely brief reversal of the geomagnetic field, climate variability and a supervolcanic eruption. 41,000 years ago, a complete and rapid reversal of the geomagnetic field occurred. Magnetic studies of the GFZ German Research Centre for Geosciences on sediment cores from the Black Sea show that during this period, during the last ice age, a compass at the Black Sea would have pointed to the south instead of north.

Moreover, data obtained by the research team formed around GFZ researchers Dr. Norbert Nowaczyk and Prof. Helge Arz, together with additional data from other studies in the North Atlantic, the South Pacific and Hawaii, prove that this polarity reversal was a global event. Their results are published in the latest issue of the scientific journal “Earth and Planetary Science Letters.”

What is remarkable is the speed of the reversal: “The field geometry of reversed polarity, with field lines pointing into the opposite direction when compared to today’s configuration, lasted for only about 440 years, and it was associated with a field strength that was only one quarter of today’s field,” explains Norbert Nowaczyk. “The actual polarity changes lasted only 250 years. In terms of geological time scales, that is very fast.” During this period, the field was even weaker, with only 5% of today’s field strength. As a consequence, the Earth nearly completely lost its protection shield against hard cosmic rays, leading to a significantly increased radiation exposure. This is documented by peaks of radioactive beryllium (10Be) in ice cores from this time, recovered from the Greenland ice sheet. 10Be as well as radioactive carbon (14C) is caused by the collision of high-energy protons from space with atoms of the atmosphere.

The polarity reversal now found with the magnetisation of Black Sea sediments has already been known for 45 years. It was first discovered after the analysis of the magnetisation of several lava flows near the village Laschamp near Clermont-Ferrand in the Massif Central, which differed significantly from today’s direction of the geomagnetic field. Since then, this geomagnetic feature is known as the ‘Laschamp event.’ However, the data of the Massif Central represent only some point readings of the geomagnetic field during the last ice age, whereas the new data from the Black Sea give a complete image of geomagnetic field variability at a high temporal resolution.

Besides giving evidence for a geomagnetic field reversal 41,000 years ago, the geoscientists from Potsdam discovered numerous abrupt climate changes during the last ice age in the analyzed cores from the Black Sea, as it was already known from the Greenland ice cores. This ultimately allowed a high precision synchronization of the two data records from the Black Sea and Greenland

. The largest volcanic eruption on the Northern hemisphere in the past 100 000 years, namely the eruption of the super volcano 39400 years ago in the area of today’s Phlegraean Fields near Naples, Italy, is also documented within the studied sediments from the Black Sea. The ashes of this eruption, during which about 350 cubic kilometers of rock and lava were ejected, were distributed over the entire eastern Mediterranean and up to central Russia. These three extreme scenarios, a short and fast reversal of the Earth’s magnetic field, short-term climate variability of the last ice age and the volcanic eruption in Italy, have been investigated for the first time in a single geological archive and placed in precise chronological order.

Scientists have ‘limited knowledge’ of how climate change causes extinction

By Ian Sample, The Guardian
Wednesday, October 17, 2012 8:58 EDT

Panamanian golden frog (Shutterstock)

Review finds loss of plants and animals due to global warming is already widespread, but the causes are poorly understood

A major review into the impact of climate change on plants and animals has found that scientists have almost no idea how it drives various species to extinction.

Though some organisms struggle to cope physiologically with rising temperatures – a simple and direct result of climate change – there was scarce evidence this was the main climate-related threat to many species whose numbers were already falling.

More often, climate change took its toll on life through more complex and indirect routes, such as reducing the abundance of food, making diseases more rife, and disturbing natural encounters between species, the review concludes.

The report warns that scientists have “disturbingly limited knowledge” on the crucial issue, and that many species may become extinct long before their inability to cope physically with warmer conditions becomes a danger.

“This is arguably the most important topic in biology and the simple question of what actually causes a population to go extinct through climate change is completely understudied,” said John Wiens, an evolutionary ecologist at Stony Brook University in New York.

Understanding the precise ways that climate change impacted on different species was now “an urgent priority” for future research, he added.

Wien’s group analysed 136 published studies that described local extinctions attributed to climate change. Only seven of the papers identified a primary mechanism for the species’ disappearance. None showed a simple relationship between species loss and the organism’s tolerance of higher temperatures.

Despite a wealth of studies describing how species adapted to climate change, by moving to new habitats, for example, Wiens said the details of how climate forces populations into decline were still largely unknown.

Full Article

However, that doesn’t stop them from making wild claims about what causes it (man) and proceeding to make us all feel really, really bad about it…

The sad state of biodiversity

17 October 2012 | last updated at 10:22PM

HYDERABAD, India: Over 400 species were added Wednesday to the “Red List” of threatened plants and animals. Here is a factfile on biodiversity as ministers meet under the auspices of the UN Convention on Biological Diversity (CBD) in Hyderabad, India.

 

— Out of 65,518 species on the “Red List” compiled by the International Union for Conservation of Nature (IUCN), 20,219 are at risk of extinction.
— Of these, 4,088 are critically endangered, 5,919 endangered and 10,212 considered vulnerable. Sixty-three species survive only in captivity and 795 have been completely wiped out.
— Threatened groups include 41 percent of all amphibian species, 33 percent of reef-building corals, 25 percent of mammals, 20 percent of plants and 13 percent of birds.
— Last year, scientists wrote in the journal Nature that man may have unleashed the sixth known mass extinction in Earth’s history — the last having wiped out the dinosaurs some 65 million years ago.
— About 1.75 million species of plants, insects and microorganisms have so far been identified by researchers, with scientists estimating there are between three million and 100 million species on Earth.
— Fifty percent of the world’s wetlands have been destroyed in the last 100 years, according to an ongoing research project entitled TEEB, or The Economics of Ecosystems and Biodiversity.
— Among these, mangroves shrank by 20 per cent (3.6 million hectares) since 1980.
— Human expansion has led to the destruction of six million hectares of primary forest every year since 2006, according to the IUCN.
— The percentage of ocean fish stocks that are overexploited, depleted or recovering from depletion rose from 10 percent in 1974 to 32 percent in 2008.
— TEEB leader, Indian economist Pavan Sukhdev, has estimated that biodiversity loss comes at a cost of between 1.35 trillion and 3.1 trillion euros ($1.75 trillion and $4 trillion) per year.
— Countries had pledged under the Millennium Development Goals to achieve a “significant reduction” in the rate of plant and animal loss by 2010, a goal the UN has admitted was badly missed.
— The last CBD conference in Nagoya, Japan in 2010, adopted a 20-point plan to turn back biodiversity loss by 2020.
— The plan’s targets include halving the rate of habitat loss, expanding water and land areas under conservation, preventing the extinction of species currently on the threatened list, and restoring at least 15 percent of degraded ecosystems. — AFP

The World’s Most Powerful Climate Change Supercomputer Powers Up

By Matt Peckham | @mattpeckham | October 17, 2012
Carlye Calvin / NCAR

For all the political discord over climate change, one thing everyone can probably agree on is that when you’re throwing computational resources at modeling weather, the more the merrier.

Think of the new computer that just came online at the NCAR-Wyoming Supercomputing Center in Cheyenne, Wyoming as a kind of dream come true from a meteorological standpoint, then, because it represents a mammoth increase in raw crunch-prowess, dedicated to studying everything from hurricanes and tornadoes to geomagnetic storms, tsunamis, wildfires, air pollution and the location of water beneath the earth’s surface.

(MORE: What, Exactly, Is a Supercomputer?)

Call it “Yellowstone,” because that’s what the federally funded National Center for Atmospheric Research does. It’s a supercomputer, and not just your average massively parallel monster, but a 1.5 petaflop (that’s 1,500 teraflops) IBM-designed behemoth — it can run an astonishing 1.5 quadrillion calculations per second — that as of June 2012 ranks among the top 20 most powerful computers in the world.

Only “top 20″? 1.5 petaflops is nothing to sneeze at. While the fastest supercomputer in the world today, IBM’s “Sequoia” in Livermore, San Francisco, can handle over 16 petaflops, just four years ago the world’s fastest computer (also an IBM machine, dubbed “Roadrunner”) was just celebrating breaking the record for 1-petaflop sustained performance.

According to NCAR, Yellowstone is divided into three primary sections: a blistering-fast performance cluster powered by a whopping 72,288 Intel Sandy Bridge EP processor cores, a massive 144.6 terabyte storage farm and a system for visualizing all of its data.

All told, Yellowstone rates 30 times more powerful than its predecessor, a system known as “Bluefire” that NCAR took possession of back in April 2008. At the time, Bluefire was state-of-the-art; a supercomputer capable of peaking at 76 teraflops (76 trillion calculations per second). To put that in context, NCAR says where Bluefire would take three hours to carry out an “experimental short-term weather” forecast, Yellowstone might render it in just nine minutes. And as you’d expect, the increase isn’t just a matter of raw speed: Yellowstone will also be able to model earth processes of much more daunting complexity.

“The Yellowstone supercomputer will dramatically advance our understanding of Earth,” says Al Kellie, director of NCAR’s Computational and Information Systems Laboratory (CISL) on NCAR’s website. “Its computing capacity and speed will allow us to investigate a wide range of phenomena that affect our lives, with more detail than ever before.”

Sweeping “It’s like Professor Hulk on steroids!” claims about computing power aside, let’s talk calculation specifics. How exactly will Yellowstone, which ran up a tab of between $25 and $35 million, running in a data center that cost around $70 million to build, earn its keep?

(PHOTOS: A Brief History of the Computer)

Imagine zooming down on a map in a computer browser or smartphone app, summoning enhanced geographical detail within incrementally smaller visible areas. That’s what Yellowstone claims to be able to do for climate projections, narrowing the conventional 60-square-mile units used in climate change modeling today to just seven-square-mile tranches. It’s like increasing the magnification of a microscope, then aggregating all the fine detail to weave a more scrupulous data quilt.

Take what Yellowstone aims to do for research on “thunderstorms and tornadoes,” for instance. According to NCAR:

Scientists will be able to simulate these small but dangerous systems in remarkable detail, zooming in on the movement of winds, raindrops, and other features at different points and times within an individual storm. By learning more about the structure and evolution of severe weather, researchers will be able to help forecasters deliver more accurate and specific predictions, such as which locations within a county are most likely to experience a tornado within the next hour.

Or consider how it could impact “long-term forecasting”:

Farmers, shipping companies, utilities, and other planners would benefit enormously from forecasts that accurately predict weather conditions a month in advance. Because large-scale oceanic and atmospheric patterns play such a major role at this time scale, scientists will rely on supercomputers such as Yellowstone to provide needed detail on the effects of these big patterns on future local weather events. Yellowstone’s size also allows for more ensembles—multiple runs of the same simulation, each with a small change in the initial conditions—that can shed important light on the skill of longer-term forecasts.

NCAR says Yellowstone will also be able to help “work toward the development of seasonal forecasts of sea ice,” improve fire pattern predictions when wildfires break out, locate with more precision gas and oil in areas miles beneath the earth’s surface (as well as subsurface areas that could be used to store carbon) and lay the groundwork for pollutant modeling, which could yield more accurate air quality forecasts days in advance.

Up first, Yellowstone will tackle 11 research projects that NWSC technology developer director Rich Loft says will “try to do some breakthrough science straight away and try to shake the machine” (via Computerworld).

“We want to see what happens when users beat on it instead of just doing acceptance testing.”

No, Global Warming Hasn’t ‘Stopped’

Discovery News

Analysis by Kieran Mulvaney
Wed Oct 17, 2012 09:31 AM ET

Glacier92

The headline was catnip to climate change deniers:

“Global Warming Stopped 16 Years Ago, Says Met Office Report Quietly Released.”

It hits all the right notes: Global warming is a myth; and ‘they’ know it’s a myth and are trying to keep it quiet. (The ‘they’ in this context – the Met Office – is Britain’s national weather forecasting service. Met is an abbreviation for Meteorological.)

The article, in the London tabloid Daily Mail, goes on to state: “The world stopped getting warmer almost 16 years ago, according to new data released last week. The figures, which have triggered debate among climate scientists, reveal that from the beginning of 1997 until August 2012, there was no discernible rise in aggregate global temperatures … The new data, compiled from more than 3,000 measuring points on land and sea, was issued quietly on the internet, without any media fanfare, and, until today, it has not been reported.”

It is said that there is nothing new under the Sun, and the denialist argument that there has been no warming since 1997 or 1998 is an oft-repeated one. We’ve addressed it here several times, notably back in 2009 when ‘Washington Post’ columnist George Will was repeating it a great deal.

It seemed to, ahem, cool down a little when 2010 moved ahead of 1998 in the medal race for World’s Hottest Year – but, as John Cook of the excellent Skeptical Science blog said when I mentioned the Daily Mail article to him, “I fully expect to see this ‘global warming has stopped’ myth repeated for many years to come.” Indeed, David Rose, author of the ‘Daily Mail’ article, has been repeating that same line for some time himself.

So what’s the story? It should first of all be pointed out that, contrary to the headline’s claims, the Met Office didn’t “quietly release” any report – it simply updated its ongoing temperature data set. It should also be pointed out that a scientist whom Rose quoted as saying that the news showed climate models are ‘deeply flawed’ in fact insists she said no such thing.

The key point here is in the arbitrary starting point. Climate scientists note that while the underlying long-term trend is unmistakable, it can be masked by short-term natural variations. And 1998 was an exceptionally hot year as a result of a very strong El Niño that created a lot of atmospheric warming. (In fact, it currently occupies the bronze medal position, behind 2010 and the race-leading 2005.) Move the starting point to 1999, and the picture changes considerably.

As the aforementioned Skeptical Science has observed, there’s a wrong way to look at long-term trends:

Skeptics10
And there’s a right way:

Realists
In response to the ‘Daily Mail’ article, the Met Office posted a graph that includes a larger number of years and show the real trend quite clearly:

Ranked_combined
As can be seen, at first glance, the years seem to follow no discernible order: 2010, 2005, 1998, 2003, 2006. But the decades are color-coded, which shows that the vast majority of the hottest years are in this century, followed by the 1990s etc. As the Met Office pointed out in December 2009, “the first decade of this century has been, by far, the warmest decade on the instrumental record.”

The farther back in the instrument record one goes, the clearer the trend. Witness, for example, this graph, from last year:

BEST

HSW: How the Ocean Affects Climate

That graph is the work of the Berkeley Earth Surface Temperature (BEST) project, led by former climate skeptic – yes, skeptic – Richard Muller. As we noted last year, Muller was surprised to find that his own analysis of temperature data closely matched those of the scientists he had previously criticized. He wrote:

When we began our study, we felt that skeptics had raised legitimate issues, and we didn’t know what we’d find. Our results turned out to be close to those published by prior groups. We think that means that those groups had truly been very careful in their work, despite their inability to convince some skeptics of that. They managed to avoid bias in their data selection, homogenization and other corrections. Global warming is real. Perhaps our results will help cool this portion of the climate debate.

Alas, no. Global warming, unfortunately, has not stopped. But nor have the efforts of some to claim that it has.

Global temperatures matched record for hottest September

Record year-to-date warmth in south-central Canada, report says

CBC News

Posted: Oct 15, 2012 3:45 PM ET

Global temperatures last month matched an all-time high for the hottest September on record, U.S. scientists say, with record warmth in parts of Canada.

Global land and surface temperatures last month matched the all-time record for warmest September ever, the U.S. National Oceanic and Atmospheric Administration said Monday. Global land and surface temperatures last month matched the all-time record for warmest September ever, the U.S. National Oceanic and Atmospheric Administration said Monday. (Michael Probst/Associated Press)

Last month, the average combined land and ocean surface temperatures were 0.67 C higher than the 20th century average of 15.6 C, the National Oceanic and Atmospheric Administration said Monday.

That temperature average matched the one from September 2005, which was the warmest September on record since 1880, it added.

Higher-than-average monthly temperatures were most notable in western Canada, central Russia, Japan, western Australia, northern Argentina, Paraguay and southern Greenland, the NOAA said.

Year-to-date global land and ocean surface temperatures were the eighth-warmest January to September period, with record warmth “observed across the eastern two-thirds of the United States and south-central Canada,” the NOAA said in its global analysis report.

Last month also marked the 36th consecutive September and the 331st consecutive month that the average global temperature was higher than the 20th-century average.

Some scientists point to human-caused global warming and the loss of Arctic sea ice as the possible reason.

“What’s playing out is precisely what climate scientists said we should expect to see 20 to 30 years ago,” University of Victoria climate scientist Andrew Weaver told The Associated Press.

Weaver and NOAA climate monitoring chief Deke Arndt said two weather factors may be at play.

The La Nina weather oscillation — which is the opposite of El Nino and tends to depress global temperatures slightly — ended. And the Arctic was unusually warm and had a record amount of sea ice melting — factors that alter weather throughout the Northern Hemisphere.

Meanwhile, some regions saw below average temperatures, including far eastern Russia, western Alaska, southern Africa, parts of the upper midwest and southeast United States, and much of China, the NOAA said.

Full Article

Mysterious noise surfaces in New Zealand: low hum noise baffles Wellington residents

October 14, 2012WELLINGTON, NZ – News of the ‘Wellington hum’ has reverberated across the country with the local council inundated with calls on theories about the phenomenon. The Wellington City Council says calls have flooded in since the noise was first reported in parts of the city three days ago. The cause of the noise is still unknown but council spokesperson Clayton Anderson says there are several theories floating around. “We’ve had around 20 phone calls and got around a dozen emails from around New Zealand from people speculating what it is,” he says. One theory is that the Wellington sewerage pump station is reverberating through the pipes into people’s house. Another caller said the work being carried out on the Mt Victoria Tunnel ventilation shaft could be producing a low-pitched hum. The most bizarre theory was from a man convinced Daleks – fictional mutant aliens from the TV series Doctor Who – had surrounded the city. But Daleks or not, it appears the noise is spreading with the council receiving its first call from a resident in Berhampore last night. It takes the total to around 20 noise complaints from Mt Victoria, Mt Cook, Newtown, Berhampore and Karori. “We’ve put the word out to our business units about what could potentially be making that noise and they’ve all come back saying it’s not us,” says Mr Anderson. He says the council will continue to go out and monitor noise complaints.

Snow and unseasonably cool weather hits New South Wales

October 14, 2012AUSTRALIA – Snow has fallen across New South Wales and the ACT as a cold snap hits the region. The unseasonal weather saw residents in areas including the Blue Mountains and southern tablelands waking up to snow on Friday. There is also snow around Canberra, following the coldest October day there in more than 40 years. There was a maximum temperature of 8C in the Canberra area on Thursday, 11 degrees below the October average and the coldest since 1967. Overnight snow fell in the hills between Canberra and Bungendore and in areas around Goulburn and Crookwell to the north. The Bureau of Meteorology said many areas could see snow, frost and hail as the result of a low pressure system moving across NSW. “We’ve had quite a few reports of snow. We’re expecting snow down to 700m over many parts of the state,” said meteorologist Julie Evans. There has been 2.5cm of snow on the ground reported at Nerriga, in the southern tablelands. In the Blue Mountains, snow has been falling between Blackheath and Katoomba. Sussex Inlet on the south coast experienced a thunderstorm about 4am on Friday, with “extensive small hail” falling, Ms Evans said. “We do get this late season snow but it doesn’t happen very often,” she added. “The last time was in 2008 when we saw snow in the Snowy Mountains and central tablelands in November.” In some areas, the temperatures will struggle to reach double figures on Friday, with central western Orange seeing a high of 9C. On Saturday, temperatures will dip below zero with Walcha, in the state’s north, due to get a low of -4C. The low pressure was expected to affect Sydney in the form of heavy rain on Friday, along with a “”harp increase in wind,” Ms Evans said. Coastal areas will bear the brunt and surfing conditions were described by the meteorologist as dangerous. On Saturday there is likely to be extensive frost up and down the tablelands but temperatures are set to improve across the state as the weekend progresses. Ausgrid has warned residents in Sydney, the Central Coast and Hunter Valley to beware of power lines that may have fallen as a result of the bad weather. Ulladulla on the NSW south coast was hit by strong winds and rainfall. The town saw 225mm of rain fall in less than 24 hours and there were gusts of 47 knots on Friday morning, approaching 90km an hour. South of the town, heavy storms led to even higher falls, with 288mm at Burrill Lake in the same period. In Sydney, large swells caused the cancellation of ferries between Manly and Circular Quay. The Great Western Highway has been closed in both directions at Wentworth Falls due to heavy snow and black ice. The cold front had already swept through South Australia, causing unseasonal snow flurries around Adelaide and trapping a school group who were hiking in Victoria. In Queensland, there also have been reports of sleet hitting part of the state’s southeast.

Scientists uncover diversion of Gulf Stream path in late 2011

October 14, 2012MAINE – At a meeting with New England commercial fishermen last December, physical oceanographers Glen Gawarkiewicz and Al Plueddemann from the Woods Hole Oceanographic Institution (WHOI) were alerted by three fishermen about unusually high surface water temperatures and strong currents on the outer continental shelf south of New England. “I promised them I would look into why that was happening,” Gawarkiewicz says. The result of his investigation was a discovery that the Gulf Stream diverged well to the north of its normal path beginning in late October 2011, causing the warmer-than-usual ocean temperatures along the New England continental shelf. The researchers’ findings, “Direct interaction between the Gulf Stream and the shelfbreak south of New England,” were published in the August 2012 issue of the journal Scientific Reports. To begin to unravel the mystery, Gawarkiewicz and his colleagues assembled data from a variety of sources and recreated a record of the Gulf Stream path during the fall of 2011. “These are very dramatic events for the outer continental shelf, at least 2 degrees C warmer than we’ve seen since 2001,” says Gawarkiewicz. “Near-bottom temperatures of 18 degrees C on the outer shelf are extremely high for late autumn.” The maximum recorded temperature in December 2011 was the warmest bottom temperature recorded in 6 years of records at the OC01 site. Gawarkiewicz and his colleagues collected additional data on water temperature and salinity from December 4, 2011 through January 4, 2012, from instruments on temporary test moorings placed 12 km south of the shelfbreak by the Ocean Observatories Initiative (OOI). The researchers compared those salinity measurements to historical data, and discovered that high salinity levels – consistent with the salinity of waters carried by the Gulf Stream – coincided with the warming periods.

Next eruption could be a mega-event: scientist warns of Fuji eruption chaos

October 14, 2012JAPAN – A Japanese scientist has warned Mount Fuji is due for a “big-scale explosive eruption” that could affect millions of people and cause billions of dollars worth of damage. Last month a study found the magma chamber under the mountain has come under immense pressure, which could even trigger a volcanic eruption. It said the added pressure could have been caused by last year’s earthquake, which was followed a few days later by another large tremor directly underneath Fuji. Professor Toshitsugu Fujii, the head of Japan’s volcanic eruption prediction panel, says an eruption could cause chaos and carnage all the way to Tokyo. “Mount Fuji has been resting for 300 years now, and this is abnormal,” he told Saturday AM. “It usually erupts in some form every 30 years. So the next eruption could be a big-scale explosive eruption.” Ever since last year’s massive 9.0-magnitude earthquake off Japan’s north-east, the country’s meteorological agency has been keeping a closer eye on Mount Fuji. Of even greater concern to the agency was a magnitude-6.2 quake right under the volcano a few days after the big one. “It’s known that when a large earthquake happens, it can trigger a nearby volcano to erupt,” Professor Fujii said. “That’s what happened 300 years ago, when Fuji erupted just 40 days after a big quake.”

Earth hit by geomagnetic storm: more active region of the Sun turning towards Earth

Space Weather

October 9, 2012SUN – A geomagnetic storm is in progress as Earth passes through the wake of a CME that arrived on Oct. 8th. Reports of auroras are coming in from across Canada and all the northern-tier US states. Beth Allan sends this picture from Fort Saskatchewan, Alberta: “The auroras outside of Edmonton were so bright for a while that it was easy to walk around in the field I was standing in,” says Allan. “The lights were moving so fast and were so crisp that it felt like I could reach out and touch them. Really astounding!” High-latitude sky watchers should remain alert for auroras as Earth’s magnetic field continues to reverberate from the CME strike. A new and possibly significant active region is emerging at the circled location (below) on the sun’s northern limb.

New study finds planet’s southern hemisphere becoming drier

October 4, 2012AUSTRALIA – A decline in April-May rainfall over south-east Australia is associated with a southward expansion of the subtropical dry-zone according to research published today in Scientific Reports, a primary research journal from the publishers of Nature. CSIRO scientists Wenju Cai, Tim Cowan and Marcus Thatcher explored why autumn rainfall has been in decline across south-eastern Australia since the 1970s, a period that included the devastating Millennium drought from 1997-2009. Previous research into what has been driving the decline in autumn rainfall across regions like southern Australia has pointed the finger at a southward shift in the storm tracks and weather systems during the late 20th century. However, the extent to which these regional rainfall reductions are attributable to the poleward expansion of the subtropical dry-zone has not been clarified before now. Mr. Cowan said rainfall patterns in the subtropics are known to be influenced by the Hadley cell, the large-scale atmospheric circulation that transports heat from the tropics to the sub-tropics. “There has been a southward expansion of the edge of the Hadley cell – also called subtropical dry-zone – over the past 30 years, with the strongest expansion occurring in mid-late autumn, or April to May, ranging from 200 to 400 kilometers,” Mr Cowan said. The CSIRO researchers found that the autumn southward expansion of the subtropical dry-zone is greatest over south-eastern Australia, and to a lesser extent, over the Southern Ocean to the south of Africa. “The Hadley cell is comprised of a number of individual branches, so the impact of a southward shift of the subtropical dry-zone on rainfall is not the same across the different semi-arid regions of the Southern Hemisphere,” says CSIRO’s Dr Wenju Cai.

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