Oct 312013
 

Original story at Florida State University

Female Guppies in Trinidad Seek Rare Males as Mates

Poecilia reticulata wild type Guppy (strain after approx. 4 years random breeding in the aquarium), population Trinidad Caroni Swamp. Photo: Emilio17, Wikimedia Commons

Poecilia reticulata wild type Guppy (strain after approx. 4 years random breeding in the aquarium), population Trinidad Caroni Swamp. Photo: Emilio17, Wikimedia Commons

When it comes to choosing a mate, female guppies don’t care about who is fairest. All that matters is who is rarest.

Florida State University Professor Kimberly A. Hughes in the Department of Biological Science has a new study just published in the journal Nature that is the first to demonstrate a female preference for rare males using an experiment in a wild population, rather than a laboratory setting.

This study of genetic differences in male guppies is relevant to understanding variation in humans as well as in other organisms, Hughes said.

Hughes and her longtime collaborators studied guppies in Trinidad and found that male guppies with rare color patterns mated more — and lived longer — than the common males. The males’ color variations are genetic and not due to diet or temperature. And the males’ actual appearance didn’t matter to the females, who are tan in color and do the choosing of mates.

“No matter which color pattern we made rare in any group, they mated more and had more offspring,” Hughes said.

So, a male guppy common in one grouping, i.e., placed in a stream with many fish that look like him, is a dud to the females also in the stream. But, take that common male and place him in a different stream with only one or two others similar to him, and he’s suddenly rare — and a desirable mate.

In an earlier study, Hughes showed that male guppies with rare color patterns had a survival advantage compared to those with common patterns in natural populations. During a three-week study, also in Trinidad, 70 percent of common males survived, while 85 percent of rare males survived.

This new study, “Mating advantage for rare males in wild guppy populations,” reports the results of paternity analyses of the offspring produced by the females in that earlier field experiment.

Hughes approached this new, rare-male-as-mating-champ theory with the goal of ruling it out. She thought it was unlikely.

But, “We got a big, significant result,” she said.

Guppies (Poecilia reticulata) are an ideal species for this study, Hughes said, because the males’ color variations are so visible and because there is so much variation. Other fish show color variation but not as widely as the guppy.

“These guys are sort of the champions of variation,” she said.

And it’s not that the rare males are simply trying harder to land a female. All male guppies do elaborate mating rituals, fanning out their fins and pursuing a mate.

The next question to answer, Hughes said, is why. Why do female guppies go for the rarest male in a particular population? It’s possible that in choosing a mate who appears unknown to her, a female guppy is trying to avoid procreating with a relative, which can lead to genetic disorders in offspring.

The guppy question speaks to a longstanding puzzle within evolutionary biology: Why are individuals within species so genetically diverse?

Understanding why species are genetically diverse is key to understanding human variation in disease susceptibility, for maintaining healthy crop and livestock populations and for preserving endangered species, Hughes said.

Hughes’ collaborators in this study are Anne E. Houde of the Lake Forest College Department of Biology in Lake Forest, Ill., and Anna C. Price and F. Helen Rodd of the Department of Ecology and Evolutionary Biology at the University of Toronto in Toronto, Ontario, Canada. Their work was supported by grants from the National Science Foundation and the Natural Sciences and Engineering Research Council of Canada.

Oct 312013
 

Green group warns Mary River turtle nests destroyed amid breeding seasonOriginal story by Jon Coghill, ABC News

A conservation group says humans and livestock have destroyed the shallow nests of the vulnerable Mary River turtle on Queensland’s Sunshine Coast hinterland.

Glenda Pickersgill from the Save Mary River Coordinating Group says the reptile is in the middle of its laying season, which lasts from October to December.

Mary River Turtle with handler. Photo: Peter Gooch, ABC

Mary River Turtle with handler. Photo: Peter Gooch, ABC

She says some turtle nests have been lost after being dug up or driven over.

“There’s a few areas where we’ve seen disturbance of sandbanks and I think that’s disappointing,” she said.

“The eggs are under the surface by only 15, 16cms, so any trampling, whether it be by humans or by driving over or even by stock, can damage the clutch of eggs that’s underneath.”

She says the Mary River turtle only lays its eggs in sandy and shady areas and it is important their nests are not disturbed.

“October through to December is the main laying period,” she said.

“It’ll take about 50 to 55 days to hatch.

“There’s a few months there where they’re really vulnerable. Unless we’ve got baby Mary River turtles coming through to replace the elderly, that’s where the whole endangered aspect can be helped.”

Oct 302013
 

ABC NewsOriginal story by Bruce Atkinson, ABC News

Disaster agencies are meeting today in Gympie, one of Australia’s most flood-prone cities, to discuss preparations for the wet season.

The south-east Queensland city has had five major floods in the last two years but is currently in the middle of a dry spell.

Police, State Emergency Service (SES), council and other emergency groups will discuss their disaster plans after a briefing from the weather bureau.

Acting Mayor Tony Perrett says Gympie is well prepared.

“One of the great lessons that has come out of it for us is to make certain that we are prepared right across the region,” he said.

“Particularly flooding in the last few years has affected many of our outlying areas and we’ve managed to establish community information groups right across the region.

“They’re our eyes and ears in respect of the way the community operates and what they’re observing.”

Councillor Perrett says the dissemination of information by the local disaster management group (LDMG) during and after disasters is vital.

“That’s something, particularly in this region, we’ve been quite good at,” he said.

“At the end of the day, we’re only as good as the information we get.

“That’s why we’ve established a broader network now – to provide that information directly to the LDMG so we can provide a more timely response and particularly to work on methods of distributing that information.”

Oct 302013
 

ABC NewsOriginal story by Melinda Howells, ABC News

Resource company Sibelco says it did not get everything it wanted in negotiations with the Queensland Government over its sand mining leases on North Stradbroke Island.

A parliamentary committee is examining new laws that would extend sand mining on the Island off Brisbane until 2035.

Sibelco CEO Campbell Jones was questioned about meetings with Premier Campbell Newman to negotiate the proposed legislation.

The sand mine on North Stradbroke Island. Photo: Giulio Saggin, ABC News.

The sand mine on North Stradbroke Island. Photo: Giulio Saggin, ABC News.

“No we didn’t get everything that we wanted,” he said.

“There is not a restoration of all of our tenure.”

Sibelco says it injects $130 million a year into the region and the new laws balance economic and environmental interests.

It says the previous government’s plan to close the largest mine by 2019 would have hurt the local economy.

But environmental groups say an extension of sand mining on North Stradbroke will harm the island’s ecosystem.

Evan Hamman from the Environmental Defenders Office says the legislation states that the Government must extend mining leases with no avenues for appeal in the courts.

“There shouldn’t be special legislation in this regard, it’s unprecedented,” he said.

Paul Donatiu from the National Parks Association of Queensland says lakes and wetlands are under threat.

“It puts at risk these incredible, beautiful and rare places,” he said.

Cleveland MP Mark Robinson’s electorate takes in North Stradbroke.

He questioned the motives of some people giving evidence, asking about their links to the island.

“Are you just anti mining? How many of your members actually live on the island, are residents?” he said.

Oct 302013
 

Media release from NOAA

A new modeling study shows that widespread bleaching events like this one in Thailand in 2010 will become more common in the future. However, the study also found signs corals may be adapting to warming -- the question is if it can be fast enough to keep up with the rate humans are burning fossil fuels. Ohoto: C. Mark Eakin/NOAA

A new modeling study shows that widespread bleaching events like this one in Thailand in 2010 will become more common in the future. However, the study also found signs corals may be adapting to warming — the question is if it can be fast enough to keep up with the rate humans are burning fossil fuels. Ohoto: C. Mark Eakin/NOAA

Coral reefs may be able to adapt to moderate climate warming, improving their chance of surviving through the end of this century, if there are large reductions in carbon dioxide emissions, according to a study funded by NOAA and conducted by the agency’s scientists and its academic partners. Results further suggest corals have already adapted to part of the warming that has occurred.

“Earlier modeling work suggested that coral reefs would be gone by the middle of this century. Our study shows that if corals can adapt to warming that has occurred over the past 40 to 60 years, some coral reefs may persist through the end of this century,” said study lead author Cheryl Logan, Ph.D., an assistant professor in California State University Monterey Bay’sDivision of Science and Environmental Policy. The scientists from the university, and from theUniversity of British Columbia, were NOAA’s partners in the study.

Warm water can contribute to a potentially fatal process known as coral “bleaching,” in which reef-building corals eject algae living inside their tissues. Corals bleach when oceans warm only 1-2°C (2-4°F) above normal summertime temperatures. Because those algae supply the coral with most of its food, prolonged bleaching and associated disease often kills corals.

The study, published online in the journal Global Change Biology, explores a range of possible coral adaptive responses to thermal stress previously identified by the scientific community. It suggests that coral reefs may be more resilient than previously thought due to past studies that did not consider effects of possible adaptation.

The study projected that, through genetic adaptation, the reefs could reduce the currently projected rate of temperature-induced bleaching by 20 to 80 percent of levels expected by the year 2100, if there are large reductions in carbon dioxide emissions.

“The hope this work brings is only achieved if there is significant reduction of human-related  emissions of heat-trapping gases,” said Mark Eakin, Ph.D., who serves as director of the NOAA Coral Reef Watchmonitoring program, which tracks bleaching events worldwide. “Adaptation provides no significant slowing in the loss of coral reefs if we continue to increase our rate of fossil fuel use.”

“Not all species will be able to adapt fast enough or to the same extent, so coral communities will look and function differently than they do today,” CalState’s Logan said.

While this paper focuses on ocean warming, many other general threats to coral species have been documented to exist that affect their long-term survival, such as coral disease, acidification, and sedimentation. Other threats to corals are sea-level rise, pollution, storm damage, destructive fishing practices, and direct harvest for ornamental trade.

According to the Status of Coral Reefs of the World: 2000 report, coral reefs have been lost around the world in recent decades with almost 20 percent of reefs lost globally to high temperatures during the 1998-1999 El Niño and La Niña and an 80 percent percent loss of coral cover in the Caribbean was documented in a 2003 Science paper. Both rates of decline have subsequently been documented in numerous other studies as an on-going trend.

Tropical coral reef ecosystems are among the most diverse ecosystems in the world, and provide economic and social stability to many nations in the form of food security, where reef fish provide both food and fishing jobs, and economic revenue from tourism. Mass coral bleaching and reef death has increased around the world over the past three decades, raising questions about the future of coral reef ecosystems.

In the study, researchers used global sea surface temperature output from the NOAA/GFDL Earth System Model-2 for the pre-industrial period though 2100 to project rates of coral bleaching.

Because initial results showed that past temperature increases should have bleached reefs more often than has actually occurred, researchers looked into ways that corals may be able to adapt to warming and delay the bleaching process.

The article calls for further research to test the rate and limit of different adaptive responses for coral species across latitudes and ocean basins to determine if, and how much, corals can actually respond to increasing thermal stress.

In addition to Logan, the other authors of the paper were John Dunne, NOAA Geophysical Fluid Dynamics Laboratory; Eakin, NOAA’s Coral Reef Watch; and Simon Donner, Department of Geography at the University of British Columbia. NOAA’s Coral Reef Conservation Program funded the study.

NOAA’s mission is to understand and predict changes in the Earth’s environment, from the depths of the ocean to the surface of the sun, and to conserve and manage our coastal and marine resources. Join us on FacebookTwitterInstagram and our other social media channels.

Oct 292013
 

The ConversationOriginal story by Shannon Klein, Griffith University and Kylie Pitt, Griffith University at The Conversation

For the people of northern Australia, dangerous jellyfish stings are all too common. But under changing ocean conditions, could more of these dangerous jellyfish be moving farther south along the Queensland coast?

An adult Irukandji jellyfish, which vary in size being from as small as your thumb to as large as your palm. Photo: Dr Jamie Seymour

An adult Irukandji jellyfish, which vary in size being from as small as your thumb to as large as your palm. Photo: Dr Jamie Seymour

Increasing ocean temperatures and strengthening ocean currents are causing many marine species to migrate polewards. Among the species predicted to expand their distribution is the potentially deadly Irukandji jellyfish, which are found in tropical regions around the world, including northern Queensland.

If these jellyfish do reach south-east Queensland waters, it could have a severe impact on local tourism and human health in coming generations.

Our new research, published today in Global Change Biology, looked at whether the jellyfish was more or less likely to migrate towards sub-tropical regions between now and 2100, using Queensland as our case study.

A tiny sting, then a shock to the system

With a translucent body that makes them almost invisible in the water, Irukandji jellyfish fire venom-filled stingers into their victims, which most humans barely feel at first.

But up to two hours after the sting, people stung by one of these jellyfish can start feeling multiple symptoms of the debilitating “Irukandji syndrome”.

Those symptoms can include vomiting, generalised sweating and severe pain in the back, limbs or abdomen, a sense of impending doom and a rapid heart beat. (You can read more on the symptoms and what you should do if stung here.)

Spreading south

While Queensland is a “hot spot” for Irukandji stings, these jellyfish have historically been confined to waters north of Gladstone.

But in March 2007 an adult Irukandji jellyfish was recorded for the first time as far south as Hervey Bay, just over three hours drive north of Brisbane, and there have been numerous reports of people being stung by Irukandji in this region.

The concern is that these tropical jellyfish could already be being transported south on the East Australian Current – the undersea highway made famous in Finding Nemo – towards the densely populated areas of southeast Queensland.

To establish a population outside of its normal range, a species must be able to tolerate the extremes of summer heat and winter cold in the local environment.

Our oceans are warming, with the CSIRO and others noting “striking evidence of extensive southward movements of tropical fish and plankton species in southeast Australia”. This is particularly apparent on the eastern coast of Australia, with the strengthening East Australian Current delivering warmer tropical waters farther south.

We are also seeing increasing signs of our oceans becoming more acidic.

So with all those changes underway, and expected to continue this century, we need to consider how Irukandji jellyfish could respond.

An Irukandji polyp, about 1mm big, magnified. Photo: Dr Jamie Seymour

An Irukandji polyp, about 1mm big, magnified. Photo: Dr Jamie Seymour

Like many species of jellyfish, Irukandji have a complex life history. The stage we recognise as a “jellyfish” is the adult stage. The adults produce larvae that swim to the sea floor and turn into tiny polyps just 1-2 millimetres high – smaller than a match head – which can produce more polyps by budding. When conditions are favourable, these polyps change into jellyfish.

Our research, published today, undertook climate change simulation experiments to determine whether the polyps of one species of Irukandji jellyfish could tolerate the current and the future, looking at winter and summer temperature and acidification conditions predicted for south-east Queensland around 2100.

We found that polyps budded prolifically under warmer temperatures, but although they survived more acidic conditions, their budding was inhibited.

However, the relative rates at which temperature and acidity change in the future may influence whether Irukandji jellyfish are capable of moving south.

If waters continue to warm but acidification proceeds more slowly than predicted, then Irukandji could migrate farther south in the short term.

What’s stopping them moving into southern Queensland?

Our most interesting finding was that Irukandji polyps can already tolerate both the current winter and summer temperature and acidity conditions in south-east Queensland waters. So why aren’t they seen there already?

One factor that could be preventing them being a more common sight in the region is a lack of suitable habitat for the polyps of the Irukandji species. While scientists have never been able to find polyps in their natural environment, adult jellyfish have been observed spawning near coral reefs on the Great Barrier Reef, suggesting that coral reefs may be their natural habitat.

Coral reefs do exist in south-east Queensland, but their total area and diversity is small and this may prevent populations of Irukandji from becoming established south of the Great Barrier Reef.

However, even if populations of polyps do not colonise south-east Queensland, the strengthening East Australian Current may transport jellyfish produced by polyps located in Great Barrier Reef waters into south-east Queensland.

So although the jellyfish may reach south-east Queensland in the future, our research raises some hope that they may not thrive.

Shannon Klein receives funding from the Adaptation Research Network for Marine Biodiversity and Resources (a National Climate Change Adaptation Research Facility network) and Griffith University.

Kylie Pitt received funding from a Griffith University / James Cook University Collaborative Grant in relation to the research discussed in this article

The Conversation

This article was originally published at The Conversation.
Read the original article.

Oct 272013
 

Original story by , Sydney Morning Herald

The author of a report that lays bare the connection between climate change and extreme bushfires has expressed his ”frustration” with Prime Minister Tony Abbott and Environment Minister Greg Hunt for their refusal to accept scientific consensus on climate change.

Professor Will Steffen, who co-authored the soon-to-be-released bushfire report by the Climate Council, was responding to Mr Abbott’s assertion in a newspaper interview with leading climate sceptic Andrew Bolt that drawing a link between the savage fires now plaguing NSW and climate change was ”complete hogwash”.

We never go to secondary sources like that.

“We never go to secondary sources like that.”: Professor Will Steffen. Photo: Alex Ellinghausen

The Climate Council report, a summary of which was revealed by Fairfax Media on Friday, found a clear link between rising temperatures and a longer, more dangerous bushfire season in south-eastern Australia.

”We would certainly prefer that this debate be elevated to the real scientific facts as are reported in the scientific literature and as are assessed very competently by the IPCC, the CSIRO and the Bureau [of Meteorology] and the scientists we rely on,” Professor Steffen said.

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”We’d like to see a debate in this country that gets beyond these futile arguments about the science, which have been settled for decades in the scientific literature, and get on with the real debate about what is really the best way forward with dealing with the problem.

”So, yes, it is frustrating having to go back again and again and again and talk about what the science actually says.”

He said if the climate keeps warming at the current rate, the number of days of extreme fire danger each year will double by the middle of the century.

”That’s a worst-case scenario and we certainly hope we don’t get there. But to make sure we don’t get there we have to get emissions of greenhouse gases down very rapidly and very deeply,” he said.

”For us it’s very clear cut, we are seeing an influence of climate change on bushfire conditions, particularly bushfire risk.”

But Professor Steffen said it was too early to determine whether the NSW fires are ”unprecedented” for their unseasonal ferocity – as has been asserted by the NSW Rural Fire Service.

The Climate Council, which was reformed as an independent body after Mr Hunt abolished it on his second day in the job, will release the report in full next month. It collates 60 pieces of peer-reviewed scientific literature on climate change and fire.

Professor Steffen said Wikipedia, the crowd-edited online encyclopaedia, was not one of his research tools: ”We never go to secondary sources like that.”

Mr Hunt has been criticised for citing Wikipedia as evidence that bushfires are a perennial Australian hazard, unrelated to a warming climate.

On Friday, the Australian Library and Information Association issued a public letter urging the minister to rely on ”well-researched facts”.

The letter states: ”If the slashing of government libraries continues, we will see more politicians quoting Wikipedia and fewer using high quality scientifically proven facts when making life-changing decisions. Hopefully this gaffe will encourage the minister to use his own specialist library and inspire other ministers to ensure that their libraries are fully funded and resourced.”

 

Oct 272013
 

Original story by Stephen Garnett at The Australian

A hooded plover chick on a NSW South Coast beach.

A hooded plover chick on a NSW South Coast beach.

ON July 9, 1904, Alan Owston shot a female rainbow bee-eater that had migrated north from Australia to the island of Okinawa south of Japan.

This bedraggled bird, now in the American Museum of Natural History, remains the only record of a bee-eater from Japan. Despite this, 70 years after the bird died, the bee-eater was appended to the Japan-Australia Migratory Bird Agreement.

JAMBA, as it is known, is one four international agreements that make migrants matters of national environmental significance under Australia’s foremost environmental legislation, the Environment Protection and Biodiversity Conservation Act. Because bee-eaters appear on an EPBC Act list of migrants, every environmental impact assessment has to consider whether a proposed development will have a detrimental effect on the species.

None ever have, because bee-eaters are abundant and widespread. However, for the very reason that they are so common, almost every environmental consultant has a copy-and-paste paragraph justifying why bee-eaters should again be ignored – though they have sometimes had to argue hard to convince those setting conditions.

Forty years ago the author of the JAMBA schedules was probably pleased to get any bird recognised under international law. The same list includes several extinct species and one, the Roper River scrub-robin, which we now think never existed.

Today, however, such inclusions are seen as at best a waste of time, at worst a major unnecessary impediment. So too are the many marine species than never touch the sea – including some that never cross water at all if they can help it. Birds like Trumpet Manucodes that never fly across water, even to islands just offshore, are still listed as marine species.

Such errors in listing are more than petty mistakes. They can have major ramifications – both for the species they miss and the species wrongly included.

To take the first group – the ones that ought to be listed. In 2010 I led a review of the status of Australia’s birds using mostly the same criteria used to list species under the EPBC Act. The experts around the country who contributed to that year-long review concluded that 125 species and subspecies of Australian bird are threatened. The EPBC list includes just 91 of those.

Similarly 53 per cent of the 206 birds that regularly cross Australian borders on migration are omitted from the migratory bird list attached to the EPBC Act.

As a result, birds well known to be threatened, like the Hooded Plovers that try to survive on the increasingly busy beaches of south-east Australia, remain unprotected despite ongoing declines.

The Threatened Species Scientific Committee, which overseas listing, is well aware of the deficiencies of its lists and has been trying to do something about it. However, despite the efforts of the under-resourced and overworked staff in the Department of Environment, attempts to update the list are glacial given the processes currently used for assessment.

Listing currently involves detailed submissions by members of the public that are exhaustively reviewed one by one, each review taking months. Almost 85pc of species on the EPBC lists are unchanged since the Act was drawn up in 1999. Most of these were a legacy of lists developed earlier still. Despite huge changes in threats, numbers and knowledge, it will be 2060 before all listed species are reviewed let alone deserving new ones added.

Originally the Act did insist that the lists had to be kept up to date. However, after a review pointed out that this wasn’t happening, amendments passed in 2006 simply deleted the obligation. Of course, every review of the Act since then has pointed out the same problem, the latest being a Senate committee report handed down just before the recent election.

Reviews have also noted that omissions to the list are only part of the issue. Equally problematic are the species that are included on lists erroneously.

For birds, our review suggested that 22 of the EPBC listed “threatened species” probably should not be there. Similarly 32pc of the listed 287 migratory birds do not meet the definitions of migratory under the Act and only 38pc of the nearly 293 bird species listed as marine occur regularly in Commonwealth waters.

Bad listings damage the credibility and legitimacy of the Act.

As an example, the golden sun-moth used to be found only in native grasslands and grassy woodlands. These have lost 99pc of their original extent and the species is listed as “critically endangered” – the closest category to extinction. Now the moth has learnt to eat Chilean needle-grass, a noxious weed. Some companies with sun moth habitat dominated by Chilean needle-grass they wish to develop, have not only had to buy areas of native grassland to offset sun-moth habitat loss but have also had to destroy the needle-grass in which the moth was found.

Another example is the southern subspecies of squatter pigeon. In the nineteenth century it disappeared from NSW. However, it remains widespread through eastern Queensland as far north as the Atherton Tablelands. It remains listed as threatened under the Act even though it has been known for at least 15 years that the subspecies does not meet the listing criteria. As a result, it comes up time and again in assessments and has to be accommodated in conservation plans.

Most companies roll over when faced with obligations, even if absurd, because they need the permit. They do what is needed and get on with their business. But the payments rankle and provide fertile ground for concerns over green tape.

Bad listings end up bringing the Act into disrepute by insisting on the protection of environmental values that are not threatened and holding up developments that, under other circumstances, would be seen as legitimate.

As recognised by the Senate Committee, the solution is not all that difficult. Under current arrangements nominations for listing are sent to experts for review. This then influences the recommendations of the committee. The solution would be for those experts to review the lists in their entirety, assessing public submissions as part of the review. For only a few contentious species would the committee’s judgement be required.

Such reviews could also make recommendations for removal of non-threatened species from lists – something that can currently only be initiated by the TSSC itself. At the moment, this rarely happens because the committee is so busy trying to ensure the list of the genuinely threatened is complete.

Migratory and marine species could readily be dealt with through the same process, though this would need agreement from partner countries.

Money spent by companies on threatened species as part of development proposals far outstrips any direct conservation expenditure. However, such outlays are an investment by the people in biodiversity since many of these costs are tax-deductible. It is therefore essential that they do actually benefit conservation not just pay expensive lip-service.

Surveys have shown that by far the majority of Australians do not want extinctions to occur. Many people, however, have heard stories of developments being delayed to protect species that seem to them to be coping pretty well.

They are often right. It is only with better lists that the EPBC Act will regain its social license and environmental regulation will be seen again as a legitimate way of protecting natural heritage that is at genuine risk of being lost or damaged.

Stephen Garnett is professor of conservation and sustainable livelihoods at Charles Darwin University

Oct 252013
 

Media release from the University of Colorado Boulder

The heat is on, at least in the Arctic.

CU-Boulder Professor Gifford Miller is shown here collecting dead plant samples from beneath a Baffin Island ice cap. Photo: Gifford Miller, University of Colorado Boulder

CU-Boulder Professor Gifford Miller is shown here collecting dead plant samples from beneath a Baffin Island ice cap. Photo: Gifford Miller, University of Colorado Boulder

Average summer temperatures in the Eastern Canadian Arctic during the last 100 years are higher now than during any century in the past 44,000 years and perhaps as long ago as 120,000 years, says a new University of Colorado Boulder study.

The study is the first direct evidence the present warmth in the Eastern Canadian Arctic exceeds the peak warmth there in the Early Holocene, when the amount of the sun’s energy reaching the Northern Hemisphere in summer was roughly 9 percent greater than today, said CU-Boulder geological sciences Professor Gifford Miller, study leader. The Holocene is a geological epoch that began after Earth’s last glacial period ended roughly 11,700 years ago and which continues today.

Miller and his colleagues used dead moss clumps emerging from receding ice caps on Baffin Island as tiny clocks.  At four different ice caps, radiocarbon dates show the mosses had not been exposed to the elements since at least 44,000 to 51,000 years ago.

Since radiocarbon dating is only accurate to about 50,000 years and because Earth’s geological record shows it was in a glaciation stage prior to that time, the indications are that Canadian Arctic temperatures today have not been matched or exceeded for roughly 120,000 years, Miller said.

“The key piece here is just how unprecedented the warming of Arctic Canada is,” said Miller, also a fellow at CU-Boulder’s Institute of Arctic and Alpine Research. “This study really says the warming we are seeing is outside any kind of known natural variability, and it has to be due to increased greenhouse gases in the atmosphere.”

A paper on the subject appeared online Oct. 23 in Geophysical Research Letters, a journal published by the American Geophysical Union. Co-authors include CU-Boulder Senior Research Associate Scott Lehman, former CU-Boulder doctoral student and now Prescott College Professor Kurt Refsnider, University of California Irvine researcher John Southon and University of Wisconsin, Madison Research Associate Yafang Zhong.  The National Science Foundation provided the primary funding for the study.

Miller and his colleagues compiled the age distribution of 145 radiocarbon-dated plants in the highlands of Baffin Island that were exposed by ice recession during the year they were collected by the researchers. All samples collected were within 1 meter of the ice caps, which are generally receding by 2 to 3 meters a year. “The oldest radiocarbon dates were a total shock to me,” said Miller.

Located just east of Greenland, the 196,000-square-mile Baffin Island is the fifth largest island in the world.  Most of it lies above the Arctic Circle. Many of the ice caps on the highlands of Baffin Island rest on relatively flat terrain, usually frozen to their beds. “Where the ice is cold and thin, it doesn’t flow, so the ancient landscape on which they formed is preserved pretty much intact,” said Miller.

To reconstruct the past climate of Baffin Island beyond the limit of radiocarbon dating, Miller and his team used data from ice cores previously retrieved by international teams from the nearby Greenland Ice Sheet.

The ice cores showed that the youngest time interval from which summer temperatures in the Arctic were plausibly as warm as today is about 120,000 years ago, near the end of the last interglacial period. “We suggest this is the most likely age of these samples,” said Miller.

The new study also showed summer temperatures cooled in the Canadian Arctic by about 5 degrees Fahrenheit from roughly 5,000 years ago to about 100 years ago – a period that included the Little Ice Age from 1275 to about 1900.

“Although the Arctic has been warming since about 1900, the most significant warming in the Baffin Island region didn’t really start until the 1970s,” said Miller. “And it is really in the past 20 years that the warming signal from that region has been just stunning. All of Baffin Island is melting, and we expect all of the ice caps to eventually disappear, even if there is no additional warming.”

Temperatures across the Arctic have been rising substantially in recent decades as a result of the buildup of greenhouse gases in Earth’s atmosphere. Studies by CU-Boulder researchers in Greenland indicate temperatures on the ice sheet have climbed 7 degrees Fahrenheit since 1991.

A 2012 study by Miller and colleagues using radiocarbon-dated mosses that emerged from under the Baffin Island ice caps and sediment cores from Iceland suggested that the trigger for the Little Ice Age was likely a combination of exploding tropical volcanoes – which ejected tiny aerosols that reflected sunlight back into space – and a decrease in solar radiation.

Contact:
Gifford Miller, 303-492-6962
gmiller@colorado.edu
Jim Scott, CU-Boulder media relations, 720-381-9479
jim.scott@colorado.edu

Oct 252013
 

Original story at the Daily Mercury

ENGINEERING CHANGE: Dr Andrew Brooks (right) from Griffith University and Dr Kate Steel from the Pioneer Catchment and Landcare Group prepare to construct three log jams in Owens Creek, near Gargett.

ENGINEERING CHANGE: Dr Andrew Brooks (right) from Griffith University and Dr Kate Steel from the Pioneer Catchment and Landcare Group prepare to construct three log jams in Owens Creek, near Gargett.

LANDHOLDERS around Mackay have donated more than 270 logs to create some of the region’s first “Engineered Log Jams” (ELJs) and help restore life to local rivers.

Log jam construction is set to begin this week in Owens Creek, near Gargett, using eight metre hardwood logs delivered from properties in Bloomsbury and Mirani.

This changes the behaviour of water flow, and over time will create pools and direct the channel away from the bank.

Leading the construction activities will be Australian river expert and ELJ designer Dr Andrew Brooks from Griffith University.

A series of three log jams will be constructed at a badly eroding stretch of the river.

Reef Catchments’ Water and Waterways project officer Iona Flett said the ELJ installation was an exciting concept designed to help restore the Mackay region’s riverine health.

“The logs will be arranged in a man-made ‘jam’ – essentially a criss-cross stack to slow and control water flow,” Ms Flett said.

“This changes the behaviour of water flow, and over time will create pools and direct the channel away from the bank.

“As well as the pools, the logs themselves also provide a more natural river environment for native fish, including barramundi and jungle perch, who need snags and woody debris to hide under.

“The ELJs will stabilise the river bank, which means less sediment going downstream and into the reef. Native trees and bank revegetation will also play a key part in reducing erosion.”

Gargett property owner Andrew Meredith said he was looking forward to seeing the results.

He said the creek would only continue to widen and erode the bank, which on a personal level meant a real loss of property.