20/10/14

Arctic thaw significantly worsens global warming risk



Melting ice is cooking the planet. Shrinking Arctic sea ice means the ocean is absorbing more energy from the sun, and it's now clear the effect is twice as big as thought – adding significantly to heating from greenhouse gases.
Arctic temperatures have risen 2 °C since the 1970s, leading to a 40 per cent dip in the minimum summer ice coverage in the Arctic Ocean. Open water soaks up more sunlight than ice, so as the ice retreats the ocean absorbs more energy, warming it and causing even more melting.
To measure the effect, Ian Eisenman of the Scripps Institute of Oceanography in La Jolla, California, and colleagues turned to data from NASA's CERES satellite. They found that the Arctic Ocean's albedo – the fraction of sunlight it reflects back into space – dropped from 52 per cent in 1979 to 48 per cent in 2011. That may not seem like much, but it means a big rise in energy absorbed – equal to 25 per cent of that trapped by the rise in atmospheric carbon dioxide over the same period.
"That is big – unexpectedly big," says Eisenman. "Arctic sea ice retreat has been an important player in the global warming that we've observed during recent decades."
"It reaffirms that albedo feedback is a powerful amplifier of climate change, maybe even more so than is simulated by the current crop of climate models," says Mark Flanner of the University of Michigan in Ann Arbor.
The extra energy absorbed goes into the ocean, particularly on the side of the Arctic near Alaska and Siberia, which is losing the most ice. "I don't know where it's going from there," says Eisenman. "I think this is an important piece in the climate change story, but there are lots of other pieces we need."
The future of Arctic sea ice itself is also uncertain. Arctic summers will probably be ice-free later this century, but nobody knows how soon. "Right now we have very little ability to predict Arctic ice two months or 30 years out," says Eisenman.

15/10/14

Report Today Details Abrupt Climate Change Surprises



July 29th, 2014 by 

The White House released a report this morning from the Council of Economic Advisers that shows the consequences of not doing something about climate change NOW. Our sister publication, CleanTechnica, has the full story, along with a word from noted Penn State climatologist Michael E. Mann.
One important section of the report discusses a number of abruptclimate change surprises and their potentially severe consequences. These climate change surprise events include the following (quoted from report):
• Late-summer Arctic sea ice disappearance: Strong trends of accelerating late-summer sea ice loss have been observed in the Arctic. The melting of Arctic sea ice comprises a positive feedback loop, as less ice means more sunlight will be absorbed into the dark ocean, causing further warming.
• Sea level rise (SLR) from destabilization of West Antarctic ice sheets (WAIS): The WAIS represents a potential SLR of 3-4 meters as well as coastal inundation and stronger storm surges. Much remains unknown of the physical processes at the ice-ocean frontier. However, two recent studies (Joughin, Smith, and Medley 2014, Rignot et. al. 2014) report evidence that irreversible WAIS destabilization has already started.
• Sea level rise from other ice sheets melting: Losing all other ice sheets, including Greenland, may cause SLR of up to 60 meters as well as coastal inundation and stronger storm surges. Melting of the Greenland ice sheet alone may induce SLR of 7m, but it is not expected to destabilize rapidly within this century.
• Disruption to Atlantic Meridional Overturning Circulation (AMOC): Potential disruptions to the AMOC may disrupt local marine ecosystems and shift tropical rain belts southward. Although current models do not indicate that an abrupt shift in the AMOC is likely within the century, the deep ocean remains understudied with respect to measures necessary for AMOC calculations.
• Decrease in ocean oxygen: As the solubility of gases decrease with rising temperature, a warming of the ocean will decrease the oxygen content in the surface ocean and expand existing Oxygen Minimum Zones. This will pose a threat to aerobic marine life as well as release nitrous oxide—a potent GHG—as a byproduct of microbial processes. The NRC study assesses a moderate likelihood of an abrupt increase in oxygen minimum zones in this century.
• Increasing release of carbon stores in soils and permafrost: Northern permafrost contains enough carbon to trigger a positive feedback response to warming temperatures. With an estimated stock of 1700-1800 Gt, the permafrost carbon stock could amplify considerably human-induced climate change. Small trends in soil carbon releases have been already observed.
• Increasing release of methane from ocean methane hydrates: This is a particularly potent long-term risk due to hydrate deposits through changes in ocean water temperature; the likely timescale for the physical processes involved spans centuries, however, and there is low risk [of climate change surprises from this source] this century.


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Federal study warns of sudden climate change woes


Dec. 3, 2013 6:16 PM EST

WASHINGTON (AP) — Hard-to-predict sudden changes to Earth's environment are more worrisome than climate change's bigger but more gradual impacts, a panel of scientists advising the federal government concluded Tuesday.
The 200-page report by the National Academy of Sciences looked at warming problems that can occur in years instead of centuries. The report repeatedly warns of potential "tipping points" where the climate passes thresholds, beyond which "major and rapid changes occur." And some of these quick changes are happening now, said study chairman James White of the University of Colorado.
The report says abrupt changes like melting ice in the Arctic Ocean and mass species extinctions have already started and are worse than predicted. It says thousands of species are changing their ranges, seasonal patterns or in some cases are going extinct because of human-caused climate change. Species in danger include some coral; pika, a rabbitlike creature; the Hawaiian silversword plant and polar bears.
At the bottom of the world in Antarctica, the melting ice in the west could be more of a wild card than originally thought. If the massive ice sheet melts it may happen relatively rapidly and could raise world sea levels by 13 feet, but researchers aren't certain how soon that may occur.
However, the report had what researchers called "good news." It said two other abrupt climate threats that worried researchers likely won't be so sudden, giving people more time to prepare and adapt. Those two less-imminent threats are giant burps of undersea and frozen methane, a super-potent greenhouse gas, and the slowing of deep ocean currents. That slowdown is a scenario that would oddly lead to dramatic coastal cooling and was featured in the 2004 movie "The Day After Tomorrow."
Study co-author Richard Alley of Pennsylvania State University compared the threat of abrupt climate change effects to the random danger of drunk drivers.
"You can't see it coming, so you can't prepare for it. The faster it is, the less you see it coming, the more it costs," Alley told The Associated Press. "If you see the drunk driver coming, you can get out of the way."
The scientists said the issue of sudden changes is full of uncertainties, so the world can better prepare by monitoring places like Antarctic and Greenland ice sheets more. But because of budget cuts and aging satellites, researchers have fewer measurements of these crucial indicators than they did a few years ago and will have even fewer in upcoming years, study co-author Steven Wofsy of Harvard University said.
The panel called on the government to create an early warning system.
"The time is here to be serious about the threat of tipping points so as to better anticipate and prepare ourselves for the inevitable surprises," said the report by the research arm of the federal government, which enlists independent scientists to look at major issues.
Donald Wuebbles, a University of Illinois climate scientist who wasn't part of the academy study, called it important, especially the call for better warning systems. However, outside scientist Michael Mann of Penn State said he doesn't see the need for a new warning system.
"The warning is already there, loud and clear," Mann said in an email. "The changes we are seeing in the Arctic are unprecedented in thousands of years, and they are already having a catastrophic impact on human civilizations, animals, and ecosystems there."
In a separate study, published Tuesday in the journal PLoS One, former NASA climate scientist-turned-activist James Hansen argues that the countries of the world have set the wrong goal in its fight against global warming. World leaders have set a goal of trying to keep warming to another 2 degrees Fahrenheit from now but Hansen said that would blow past tipping points and give Earth a "dangerous level" of global warming.
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Alertan sobre un fuerte temporal en aguas del Atlántico norte


La Agencia Estatal de Meteorología avisa de que una borrasca centrada al oeste de Terranova podría dar lugar a la formación de una ciclogénesis explosiva

Madrid. (Efe).- La Agencia Estatal de Meteorología (Aemet) ha alertado de que una borrasca situada sobre el Atlántico y centrada al oeste de Terranova está adquiriendo una situación profunda de manera muy rápida, lo que puede dar lugar a la formación en sucesivos días de una ciclogénesis explosiva.
La borrasca es muy extensa y de momento abarca gran parte del Atlántico Norte, lo que puede generar condiciones muy adversas en el estado de la mar, con vientos del oeste de fuerza 8 y 9 y áreas de mar arbolada, ha explicado hoy la Agencia Estatal de Meteorología (Aemet) en una nota informativa.
Se espera que el fuerte oleaje de mar de fondo provocado por la borrasca afecte también a las costas del noroeste peninsular, especialmente a partir de las últimas horas del miércoles día 15, cuando la mar de fondo alcance las costas de Galicia con una altura de olas que podrían superar los 5 ó 6 metros.
Posteriormente, es probable que esta mar de fondo, quizás con olas de 3 metros, se extienda por el resto de las costas del Cantábrico e incluso podrían alcanzar las costas de las Islas Canarias.