By: Rebecca Jacobson Scientists have been trying to create a clearer picture of how the Antarctic responds to climate change. Photo by Nerilie Abram.It’s no secret that the ice sheet is melting in Greenland. Last year, the Arctic ice cap shrunk to a record low, with only 24 percent of the Arctic Ocean…
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Cats kill billions of birds and mammals every year, new study says.
Published January 29, 2013
Maybe the butler didn’t do it. But the cat probably did.
A new study, published January 29 in Nature Communications , estimates that cats are responsible for killing billions of birds and mammals in the continental U.S. every year. The estimate: 1.4 billion to 3.7 billion bird victims and 6.9 billion to 20.7 billion mammals. Peter Marra, the senior author of the study, called the results “stunning.” (Watch: A house cat’s point of view. )
“For the last 20, 30, 40 years,” he said, “the number that has been batted around as a max was about 500 million.”
And there are a lot of potential feline killers. Over 80 million pet cats reside in American homes and as many as 80 million more stray and feral cats survive outside.
The authors found that the stray and feral cats are responsible for most of the kills. But pets aren’t exactly innocent: They are blamed for about a third of the bird action. The study also discovered that the cats mainly kill native species like chipmunks and house wrens, not invasive pests like the Norway rat (Rattus norvegicus). (Video: Secret lives of cats. )
The study is part of a larger effort to quantify the threats to birds, said Marra, an ecologist with the Migratory Bird Center at the Smithsonian Conservation Biology Institute in Washington, D.C. Cats happened to be the first threat they considered. Plans are to look at other threats related to human activity: wind turbines, buildings, automobiles, and pesticides. The research is important, Marra said, because “a lot of these causes of mortality may be reversible.” He hopes the study will aid policymakers and help cat owners realize “cats are having a larger impact than we thought.”
So what can be done about all these wild killer cats?
Current efforts to rein in America’s feral cats are insufficient. While a feral cat management technique called Trap-Neuter-Return (TNR) stops some cats from reproducing, it doesn’t stop those cats from preying on wildlife. The Humane Society of the United States supports TNR as part of the solution, but acknowledges that it will not noticeably reduce the cat population. John Hadidian, a senior scientist with the society, notes that TNR only reaches about two million cats, and it can be “cumbersome and expensive.” He hopes that the attention from papers like this will encourage novel approaches like oral contraceptives for cats.
To some cat observers, the study news was no surprise. Economist Gareth Morgan made headlines around the world last week when he launched a proposal to rid New Zealand of cats. Morgan, whose website features a cartoon kitten announcing “I love to kill,” believes that pet cats are endangering New Zealand’s birds. While his website advocates a New Zealand without cats, and he would like people to make their current cat their last, he says he really wants cats to be regulated the way dogs are. He points to laws enacted in Western Australia as an example: Cats must be registered, neutered, and microchipped. The microchip, a small identifying device embedded under the skin, can be detected by vets or authorities so they can reunite lost pets with their owners and differentiate between pets and strays. “I’m not saying they should kill their cats,” Morgan said. “If they are really into cats, that’s fine, but you must control them.”
Morgan admits this is “an emotional issue” in a country where nearly half of the households have at least one feline. “It’s not that cat owners don’t care,” Morgan said, “it’s that they haven’t thought about it.”
Meanwhile, people in the U.S. aren’t likely to turn on cats either. Cat ownership has increased from about 56 million pet cats in the mid-1990s to the current count of 80 million. Though cats are viewed as both a conservation threat and a human companion, the Humane Society’s Hadidian thinks common ground can be reached. “Both the bird people and the cat people want the same thing,” he said, “fewer cats outdoors.”
An artist’s representation of the aquatic system scientists believe is buried beneath the Antarctic ice sheet. (Credit: Zina Deretsky, NSF)
Jan. 29, 2013 — In a first-of-its-kind feat of science and engineering, a National Science Foundation (NSF)-funded research team has successfully drilled through 800 meters (2,600 feet) of Antarctic ice to reach a subglacial lake and retrieve water and sediment samples that have been isolated from direct contact with the atmosphere for many thousands of years.
Scientists and drillers with the interdisciplinary Whillans Ice Stream Subglacial Access Research Drilling project (WISSARD) announced Jan. 28 local time (U.S. stations in Antarctica keep New Zealand time) that they had used a customized clean hot-water drill to directly obtain samples from the waters and sediments of subglacial Lake Whillans.
The samples may contain microscopic life that has evolved uniquely to survive in conditions of extreme cold and lack of light and nutrients. Studying the samples may help scientists understand not only how life can survive in other extreme ecosystems on Earth, but also on other icy worlds in our solar system.
The WISSARD teams’ accomplishment, the researchers said, “hails a new era in polar science, opening a window for future interdisciplinary science in one of Earth’s last unexplored frontiers.”
A massive ice sheet, almost two miles thick in places, covers more than 95 percent of the Antarctic continent. Only in recent decades have airborne and satellite radar and other mapping technologies revealed that a vast, subglacial system of rivers and lakes exists under the ice sheet. Lakes vary in size, with the largest being Vostok Subglacial Lake in the Antarctic interior that is comparable in size to Lake Ontario.
WISSARD targeted a smaller lake (1.2 square miles in area), where several lakes appear linked to each other and may drain to the ocean, as the first project to obtain clean, intact samples of water and sediments from a subglacial lake.
The achievement is the culmination of more than a decade of international and national planning and 3 1/2 years of project preparation by the WISSARD consortium of U.S. universities and two international contributors. There are 13 WISSARD principal investigators representing eight different U.S. institutions.
NSF, which manages the United States Antarctic Program, provided over $10 million in grants as part of NSF’s International Polar Year portfolio to support the WISSARD science and development of related technologies.
The National Aeronautics and Space Administration’s (NASA) Cryospheric Sciences Program, the National Oceanic and Atmospheric Administration (NOAA), and the private Gordon and Betty Moore Foundation also provided support for the project.
The interdisciplinary research team includes groups of experts in the following areas of science: life in icy environments, led by John Priscu, of Montana State University; glacial geology, led by Ross Powell, of Northern Illinois University; and glacial hydrology, led by Slawek Tulaczyk, of the University of California, Santa Cruz.
Sharing of expertise by the groups of disciplinary experts will allow the data collected to be cast in a systemic, global context.
The WISSARD team will now process the water and sediment samples they have collected in hopes of answering seminal questions related to the structure and function of subglacial microbial life, climate history and contemporary ice-sheet dynamics.
Video surveys of the lake floor and measurements of selected physical and chemical properties of the waters and sediments will allow the team to further characterize the lake and its environs.
The approach to drilling was guided by recommendations in the 2007 National Research Council-sponsored report, “Exploration of Antarctic Subglacial Aquatic Environments: Environmental and Scientific Stewardship,” aimed to protect these unique environments from contamination.
A team of engineers and technicians directed by Frank Rack, of the University of Nebraska-Lincoln, designed, developed and fabricated the specialized hot-water drill that was fitted with a filtration and germicidal UV system to prevent contamination of the subglacial environment and to recover clean samples for microbial analyses. In addition, the numerous customized scientific samplers and instruments used for this project were also carefully cleaned before being lowered into the borehole through the ice and into the lake.
Following their successful retrieval, the samples are now being carefully prepared for their shipment off the ice and back to laboratories for numerous chemical and biological analyses over the coming weeks and months.
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Despite having little impact on global mean temperatures, waste heat may alter weather significantly
A diverse team of researchers from Scripps Institution of Oceanography ; University of California, San Diego (UCSD); Florida State University (FSU); and the National Center for Atmospheric Research (NCAR) have teamed up to examine the long term effects of waste heat on local surroundings.
I. Waste Heat Shifts Temperature Balance
Urban heat originates from a variety of sources — buildings with central heating, power plants, cars, and more. Human machines dump waste heat into the environment on a large scale locally. But globally waste heat is only estimated to account for around 0.3 percent of the total heat transported across higher latitudes by atmospheric or oceanic circulation, bumping temperatures by a mere 0.01 degrees C (about 0.02 degrees F).
The “urban heat island” effect — local warming from waste heat — is well known . But the research team suspected that waste heat might have longer-range effects too, effects that might be masked by the global trend. They dug into the issue and developed models that suggest that waste may indeed have longer-range impact, in addition to the urban heat island effect.
The new, more detailed smaller-scale models show that waste heat from cities may heat up northern regions of North America and Asia by as much as 1 degree Celsius (1.8 degrees Fahrenheit) in the winter. The heating effects can be felt up to 1,000 miles away from their source, the simulations showed. At the same time, the North American/Asian heating is coupled with a 1 degree Celsius (1.8 degrees Fahrenheit) cooling effect in Europe, which is forcing cooler winters.
Waste heat is warming North America and Asia’s north, while cooling the European north.
[Image Source: Ecofriend]
NCAR researcher Aixie Hu comments, “The burning of fossil fuel not only emits greenhouse gases but also directly affects temperatures because of heat that escapes from sources like buildings and cars. Although much of this waste heat is concentrated in large cities, it can change atmospheric patterns in a way that raises or lowers temperatures across considerable distances.”
II. What Can be Done?
Humans by and large produce much less waste heat than nature (respiration itself, the process by which living organisms harvest energetic chemicals to drive the processes of life, puts off a fair deal of waste heat). But many human cities happen to be located directly under jet stream troughs, which causes the localized impact to be amplified.
Globally in 2006 energy consumption globally was estimated to have occurred at an average of 16 terawatts (TW). The 86 largest metropolitan areas in the Northern Hemisphere are estimated to have consumed 6.7 TW of that total.
U.S. urban centers often sit under jet stream troughs. [Image Source: Blue Moon/Panoramio]
The study is arguably less about prevention, and more about understanding and coping with mankind’s localized impact on weather/climate. After all, you can’t reasonably ask people to turn off the heat in the winter or stop driving (even EVs put off waste heat).
But perhaps future urban expansion can be guided by models that place new construction in areas that suck less of the waste heat into the jet stream or alternatively suck up more in regions that are currently being cooled.
Additionally materials may be able to recapture some waste heat , decreasing the global output, while at the same time lowering costs. (But such materials are still in their very nascent stages.)
The study was published in the peer-reviewed journal Nature Climate Change.