Archive for the ‘climate change’ Category

Amount of carbon dioxide absorbed by the forest dropped 30% since from the 90s to 2000s

Amazon forest

A view is seen from the Amazon Tall Tower Observatory (ATTO) in Sao Sebastiao do Uatuma in the middle of the Amazon forest, on January 10.

The Amazon rainforest’s ability to soak up greenhouse gases from the air has fallen sharply, possibly because climate change and droughts mean more trees are dying, an international team of scientists said on Wednesday.

The world’s biggest rainforest has soaked up vast amounts of carbon dioxide. Plants use the heat-trapping gas to grow and release it when they rot or burn, but the report said that role in offsetting global warming may be under threat.

The study, of 321 plots in parts of the Amazon untouched by human activities, estimated the net amount of carbon dioxide absorbed by the forest had fallen by 30 per cent, to 1.4 billion tonnes a year in the 2000s from 2.0 billion in the 1990s.

“Forest growth has flatlined over the last decade,” lead author Roel Brienen of the University of Leeds told Reuters of the findings in the journal Nature. At the same time “the whole forest is living faster — trees grow faster, die faster.”

“The net carbon uptake of forests has significantly weakened,” he said of the study by almost 100 experts.

‘Forest growth has flatlined’

Human carbon emissions in Latin America are overtaking amounts absorbed by the Amazon for the first time, the University of Leeds said in a press release.

The scientists said it was unclear if the decline would continue and if the trend applied to other tropical forests such as the Congo basin or Indonesia.

The findings are a surprise because some computer models suggest tropical forests may grow better because carbon dioxide emitted by human use of fossil fuels acts as an airborne fertilizer.

The study said increased tree deaths might be linked to severe droughts, such as in 2005.

Study signed by nearly 100 experts

Another possibility was that man-made carbon dioxide was making trees both grow faster and die younger and that more deaths were only now becoming apparent.

If that trend continues, the make-up of the Amazon rainforest could change. Fast-growing lianes, or tropical vines, might be among the beneficiaries, Brienen said.

Christof Bigler, a forest expert at the Swiss Federal Institute of Technology in Zurich who was not involved in the study, said fast-growing trees outside the tropics also often had shorter lifespans.

“Fast-growing trees tend to have a lower root density and might be more vulnerable to attacks by insects and pathogens,” he told Reuters of his findings in Switzerland and North America.

Amazon rainforest's trees

The Amazon rainforest’s trees soak up massive amounts of greenhouse gasses, but their carbon dioxide-absorbing capacity has fallen sharply in recent years.

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ORLANDO, Fla. (Reuters) – Climate change activists blasted Florida Governor Rick Scott on Monday for leading an “Orwellian” campaign to ban employees of the state’s lead environmental agency from using such terms as “global warming” and “climate change.”

Despite coastal Florida’s vulnerability to storm surges and rising sea levels, the state’s Department of Environmental Protection was directed in 2011 not to use the phrases in official communications, according to a report by the Florida Center for Investigative Reporting.

“This is embarrassing, but worse than that, it’s very worrying,” said David Hastings, a marine science professor from Eckerd College in St. Petersburg, on Florida’s west coast.

“To have this authoritarian word control is very Orwellian, a page right out of ‘Nineteen Eighty-Four,’” he said, referring to George Orwell’s dystopian novel about widespread government surveillance.

The governor’s office and the Department of Environmental Protection denied there was a policy banning the terms. “There is no policy and it simply is not true,” said Scott’s deputy communications director, John Tupps.

Former employees of the department detailed the unwritten policy in interviews with the non-profit news agency, which reported the ban on Sunday.

Employees were told not to use the phrases ‘climate change,’ ‘global warming,’ ‘sea level rise,’ or ‘sustainability,’ attorney Christopher Byrd, who worked with the department’s Office of General Counsel from 2008 to 2013, confirmed to Reuters.

“Nobody questioned it. There was just a lot of snickers and internal chuckling,” Byrd said.

The euphemism suggested to employees for “sea level rise” was “coastal resiliency,” he said.

The prohibition began after the election of Scott, who had disputed the human impact on climate change during his 2010 campaign, according to the report.

Concerns about climate change are widely voiced by research scientists, but questioned by conservative Republicans who oppose controls on carbon emissions blamed for causing environmental damage.

Hastings was one of five climate scientists who were granted a half-hour meeting with Scott in August 2014 in which they warned him of the threat posed by a steadily rising ocean.

Harvey Ruvin, who chaired a sea level rise task force in Miami that delivered its findings last year, told Reuters it was important for Florida, with about 1,000 miles (1,600 km) of coastline, to put politics aside on the climate change issue.

“It would be very nice if we could resolve problems simply by eliminating their titles from the dictionary,” he said.

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he atmospheric research site near Barrow, Alaska

The atmospheric research site near Barrow, Alaska.

The climate-changing greenhouse effect exists and has been directly measured in the United States, a new study reports.

The results confirm what scientists had already proved through models and laboratory experiments: Pumping carbon dioxide gas into the atmosphere is warming the Earth’s surface.

“We’re actually measuring the fact that rising carbon dioxide concentrations are leading to the greenhouse effect,” said lead study author Dan Feldman, a scientist at the Lawrence Berkeley National Laboratory in California. “This is clear observational evidence that when we add carbon dioxide to the atmosphere, it will push the system to a warmer place.”

Since the late 1950s, scientists have documented rising levels of carbon dioxide and other “greenhouse gases” in Earth’s atmosphere. Laboratory tests and physics experiments indicated that these gases absorb some of the infrared radiation that Earth emits into space, thereby raising the planet’s temperature. This is called the greenhouse effect because it is similar to how a glass greenhouse traps heat, warming the air inside. Put simply, more energy is flowing into the greenhouse than is getting out, a concept that scientists call radiative forcing. [Infographic: Earth’s Atmosphere Top to Bottom]

The research team measured radiative forcing on the Earth’s surface due to carbon dioxide at two long-running atmospheric research sites owned by the Department of Energy. One is in Oklahoma and the other is near Barrow, Alaska, above the Arctic Circle.

Powerful spectrometers calibrated by the United States Office of Weights and Measures tracked the infrared radiation coming down to the surface, Feldman said. Greenhouse gases in the atmosphere absorb the Earth’s infrared energy and then scatter it in all directions, some back downward toward the surface. The instruments can detect the “fingerprint” of carbon dioxide’s infrared signal because the molecule emits and absorbs infrared energy at distinctive wavelengths.

Between 2000 and 2010, atmospheric concentrations of carbon dioxide rose at both research sites by 22 parts per million. (The parts per million number refers to the volume of carbon dioxide molecules in every million air molecules.) At the same time, the amount of downward-directed infrared energy from carbon dioxide increased. This meant the surface radiative forcing, or energy imbalance, also increased at both sites, the researchers report today (Feb. 25) in the journal Nature.

In translation: More gas in the atmosphere meant more infrared energy was reflected back at the Earth instead of escaping into space.

“This is another direct piece of evidence that supports that the increase in carbon dioxide is indeed contributing to global warming,” said Dave Turner, an atmospheric physicist at the National Severe Storms Laboratory in Oklahoma, who was not involved in the study. “It’s a roadmap as to how we can do exactly the same thing for other trace gases.”

The scientists ruled out or removed possible warming effects from clouds, weather, water vapour or problems with instrument calibration.

The added radiative forcing was 0.2 watts per square meter per decade, which is about 10 percent of the total increase due to all human activities, according to the Intergovernmental Panel on Climate Change .

“I would hope that even people who raise their eyebrows at this whole field can see there is a really robust observation underlying this,” Feldman told Live Science.

The research team is now investigating the contributions to global warming from other greenhouse gases, such as methane.

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SAN FRANCISCO (Reuters) – The strandings of a record number of sea lion pups along the California coast this year are linked to a puzzling weather pattern that has warmed their Pacific Ocean habitat and likely impacted fish populations they rely on for food, federal scientists said on Wednesday.

Some 940 stranded sea lions, mostly pups, have been treated by marine mammal centers in California so far this year, according to Justin Viezbicke, West Coast Stranding Coordinator for the U.S. National Oceanic and Atmospheric Administration.

That is well above the 240 strandings typically seen through April, and scientists suspect the emaciated pups are prematurely leaving Southern California sea lion rookeries to seek food on their own after their mothers failed to return swiftly from hunting trips to nurse.

“These little pups, so desperate and so thin, are leaving the rookeries long before they’re capable of hunting effectively,” said Shawn Johnson, director of veterinary science at the Marine Mammal Center in Sausalito, which has treated 220 stranded animals. “It’s alarming because we haven’t seen this number of stranded pups this early in 40 years.”

The strandings are unusual because the pups, born last June, aren’t supposed to be completely weaned until May.

Satellite data show sea lion mothers are foraging in traditional hunting grounds, but likely spending longer periods away, said Sharon Melin, a biologist with NOAA’s National Marine Mammal Laboratory in Seattle.

Fish populations are likely being disrupted by a layer of ocean water, some 100 meters (330 feet) deep, that is 2 to 5 degrees warmer than usual this time of year along the Pacific Coast from Baja to Alaska’s Aleutian Islands, said NOAA climatologist Nate Mantua.

The change was caused by a weather pattern involving weak northern and strong southern winds that are creating warmer-than-normal conditions.

It’s unclear how many stranded animals will die among the 300,000-strong sea lion population. In 2013, some 70 percent of nursing pups perished in what NOAA declared an “unusual mortality event” linked to strandings.

Melin said pups checked on San Miquel Island this month were 44 percent below average weight at seven months old, marking the lowest growth rate since scientists began recording such measurements in the 1990s.

Most of the stranded pups have been recovered in Southern California, but the pups also swim or are carried further north, and may eventually turn up in Washington state and Oregon, according to Johnson.

“We’re braced for more,” Johnson said.

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The Best Technology for Fighting Climate Change

When people talk about technologies that might offset climate change, they often evoke not-yet-invented marvels, like planes spraying chemicals into the atmosphere or enormous skyscrapers gulping carbon dioxide from the clouds.

But in a new report, Oxford University researchers say that our best hopes might not be so complex.

In fact, they are two things we already know how to do: plant trees and improve the soil.

Both techniques, said the report, are “no regrets.” They’ll help the atmosphere no matter what, they’re comparatively low-cost, and they carry little additional risk. Specifically, the two techniques it recommends are afforestation—planting trees where there were none before—andbiochar—improving the soil by burying a layer of dense charcoal.

Between now and 2050, trees and charcoal are the “most promising” technologies out there, it said.

It also cautioned, however, that these so-called “Negative Emissions Technologies” or NETs should only be seen as a way to stave off the worst of climate change.

“NETs should not be seen as a deus ex machina that will ‘save the day,’” its authors wrote. NETs should instead be seen as one of several tools to meet the international goal of avoiding climate change greater than 2 degrees Celsius. Another crucial tool is reducing emissions.

It’s a solution that makes sense, as forest management is one of the oldest ways that humans have shaped their environment. Before the arrival of Europeans, Native communities in the Americas had beenburning forest fires for millennia to support the growth of desirable plants like blueberries and to manage ecosystems. British communities have long practiced coppicing, a tree-cutting technique that keeps forests full of younger trees.

In other words, humanity has been “geoengineering” with trees for a very long time. The authors of the Oxford report add that afforestation will need global support in order to be successful.

“It is clear that attaining negative emissions is in no sense an easier option than reducing current emissions,” it says (emphasis mine). “To remove CO2 on a comparable scale to the rate it is being emitted inevitably requires effort and infrastructure on a comparable scale to global energy or agricultural systems.”

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