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  • richardmitnick 4:58 pm on December 4, 2017 Permalink | Reply
    Tags: A new study links extreme heat during early childhood to lower earnings as an adult, , , Global Warming, Global Warming May Harm Children for Life,   

    From MIT Tech Review: “Global Warming May Harm Children for Life” 

    MIT Technology Review
    M.I.T Technology Review

    December 4, 2017
    James Temple

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    A baby sits on a Tel Aviv beach on a hot summer’s day. Uriel Sinai | Getty Images

    A new study links extreme heat during early childhood to lower earnings as an adult.

    growing body of research concludes that rising global temperatures increase the risk of heat stress and stroke, decrease productivity and economic output, widen global wealth disparities, and can trigger greater violence.

    Now a new study by researchers at Stanford, the University of California, Berkeley, and the U.S. Department of the Treasury suggests that even short periods of extreme heat can carry long-term consequences for children and their financial future. Specifically, heat waves during an individual’s early childhood, including the period before birth, can affect his or her earnings three decades later, according to the paper, published on Monday in Proceedings of the National Academy of Sciences. Every day that temperatures rise above 32 ˚C, or just shy of 90 ˚F, from conception to the age of one is associated with a 0.1 percent decrease in average income at the age of 30.

    The researchers don’t directly tackle the tricky question of how higher temperatures translate to lower income, noting only that fetuses and infants are “especially sensitive to hot temperatures because their thermoregulatory and sympathetic nervous systems are not fully developed.” Earlier studies have linked extreme temperatures during this early life period with lower birth rate and higher infant mortality, and a whole field of research has developed around what’s known as the “developmental origins of health and disease paradigm,” which traces the impacts of early health shocks into adulthood.

    There are several pathways through which higher temperatures could potentially lead to lower adult earnings, including reduced cognition, ongoing health issues that increase days missed from school or work, and effects on non-cognitive traits such as ambition, assertiveness, or self-control, says Maya Rossin-Slater, a coauthor of the study and assistant professor in Stanford’s department of health research and policy.

    The bigger danger here is that global warming will mean many more days with a mean temperature above 32 ˚C—specifically, an increase from one per year in the average U.S. county today to around 43 annually by around 2070, according to an earlier UN report cited in the study.

    For workers who would otherwise make $50,000 annually, a single day of extreme heat during their first 21 months would cut their salary by $50. But 43 such days would translate to $2,150. Multiply that by the total population experiencing such events, and it quickly adds up to a huge economic impact. A greater proportion of citizens failing to reach their full earnings potential implies lower overall productivity and economic output.

    All of that comes on top of the ways that high temperatures directly hit the economy, mainly by decreasing human productivity and agricultural yields, according to other research. Unchecked climate change could reduce average global income by around 23 percent in 2100, and as much as 75 percent in the world’s poorest countries, according to research by UC Berkeley public policy professor Solomon Hsiang and coauthors in a 2015 Nature paper (see “Hotter Days Will Drive Global Inequality”). Notably, that excludes the devastating economic impacts of things like hurricanes and sea level rise.

    “We know that high temperatures have numerous damaging consequences for current economic productivity, at the time that the high temperatures occur,” Hsiang said in an e-mail to MIT Technology Review. “This study demonstrates a new way in which high temperatures today reduce economic productivity far into the future, by weakening our labor force.”

    The good news, at least for certain nations and demographic groups, is that air-conditioning nearly eliminates this observed effect, based on the authors’ analysis of U.S. Census data that captures how air-conditioning penetration increased in U.S. counties over time. But that could point to one more way that rising global temperatures will disproportionally harm impoverished nations, or perhaps already have.

    “In poor countries in hot climates that don’t have air-conditioning, we could imagine these effects being even more dramatic,” Rossin-Slater says.

    The study explored the results for 12 million people born in the United States between 1969 and 1977, incorporating adult earnings information from newly available data in the U.S. Census Bureau’s Longitudinal Employer Household Dynamics program. The researchers sought to isolate the impact of temperature, and control for other variables, by using “fine-scale” daily weather data and county-level birth information.

    “This study makes it very clear to see how climate change in the next few decades can affect our grandchildren, even if populations in the distant future figure out how to cool things back down,” Hsiang said.

    See the full article here .

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  • richardmitnick 8:24 am on April 19, 2017 Permalink | Reply
    Tags: , Climate Change Reroutes a Yukon River in a Geological Instant, , , Global Warming, Kaskawulsh Glacier, , Slims River Valley   

    From NYT: “Climate Change Reroutes a Yukon River in a Geological Instant” 

    New York Times

    The New York Times

    APRIL 17, 2017
    JOHN SCHWARTZ

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    An aerial view of the ice canyon that now carries meltwater from the Kaskawulsh Glacier, on the right, away from the Slims River. “River piracy” refers to one river capturing and diverting the flow of another. Credit Dan Shugar/University of Washington-Tacoma

    In the blink of a geological eye, climate change has helped reverse the flow of water melting from a glacier in Canada’s Yukon, a hijacking that scientists call “river piracy.”

    This engaging term refers to one river capturing and diverting the flow of another. It occurred last spring at the Kaskawulsh Glacier, one of Canada’s largest, with a suddenness that startled scientists.

    A process that would ordinarily take thousands of years — or more — happened in just a few months in 2016.

    Much of the meltwater from the glacier normally flows to the north into the Bering Sea via the Slims and Yukon Rivers. A rapidly retreating and thinning glacier — accelerated by global warming — caused the water to redirect to the south, and into the Pacific Ocean.

    Last year’s unusually warm spring produced melting waters that cut a canyon through the ice, diverting more water into the Alsek River, which flows to the south and on into Pacific, robbing the headwaters to the north.

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    Jim Best, a researcher, measuring water levels on the lower-flowing Slims River in early September. Credit Dan Shugar/University of Washington-Tacoma

    The scientists concluded that the river theft “is likely to be permanent.”

    Daniel Shugar, an assistant professor of geoscience at the University of Washington-Tacoma, and colleagues described the phenomenon in a paper published on Monday in the journal Nature Geoscience.

    River piracy has been identified since the 19th century by geologists, and has generally been associated with events such as tectonic shifts and erosion occurring thousands or even millions of years ago. Those earlier episodes of glacial retreat left evidence of numerous abandoned river valleys, identified through the geological record.

    In finding what appears to be the first example of river piracy observed in modern times, Professor Shugar and colleagues used more recent technology, including drones, to survey the landscape and monitor the changes in the water coursing away from the Kaskawulsh Glacier.

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    Kaskawulsh glacier junction from air
    29 August 2014
    Author Gstest

    The phenomenon is unlikely to occur so dramatically elsewhere, Professor Shugar said in a telephone interview, because the glacier itself was forming a high point in the landscape and serving as a drainage divide for water to flow one way or another. As climate change causes more glaciers to melt, however, he said “we may see differences in the river networks and where rivers decide to go.”

    Changes in the flow of rivers can have enormous consequences for the landscape and ecosystems of the affected areas, as well as water supplies. When the shift abruptly reduced water levels in Kluane Lake, the Canadian Broadcasting Corporation reported, it left docks for lakeside vacation cabins — which can be reached only by water — high and dry.

    The riverbed of the Slims River basin, now nearly dry, experienced frequent and extensive afternoon dust storms through the spring and summer of last year, the paper stated.

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    The ice-walled canyon at the terminus of the Kaskawulsh Glacier, with recently collapsed ice blocks. This canyon now carries almost all meltwater from the toe of the glacier down the Kaskawulsh Valley and toward the Gulf of Alaska. Credit Jim Best/University of Illinois

    The impacts of climate change, like sea level rise or the shrinkage of a major glacier, are generally measured over decades, not months as in this case. “It’s not something you could see if you were just standing on the beach for a couple of months,” Professor Shugar said.

    The researchers concluded that the rerouted flow from the glacier shows that “radical reorganizations of drainage can occur in a geologic instant, although they may also be driven by longer-term climate change.” Or, as a writer for the CBC put it in a story about the phenomenon last year, “It’s a reminder that glacier-caused change is not always glacial-paced.”

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    Looking up the Slims River Valley, from the south end of Kluane Lake. The river used to flow down the valley from the Kaskawulsh glacier. (Sue Thomas)

    The underlying message of the new research is clear, said Dr. Shugar in a telephone interview. “We may be surprised by what climate change has in store for us — and some of the effects might be much more rapid than we are expecting.”

    The Nature Geoscience paper is accompanied by an essay from Rachel M. Headley, an assistant professor of geoscience and glacier expert at the University of Wisconsin-Parkside.

    “That the authors were able to capture this type of event almost as it was happening is significant in and of itself,” she said in an interview via email. As for the deeper significance of the incident, she said, “While one remote glacial river changing its course in the Yukon might not seem like a particularly big deal, glacier melt is a source of water for many people, and the sediments and nutrients that glacier rivers carry can influence onshore and offshore ecological environments, as well as agriculture.”

    Her article in Nature Geoscience concludes that this “unique impact of climate change” could have broad consequences. “As the world warms and more glaciers melt, populations dependent upon glacial meltwater should pay special attention to these processes.”

    Another glacier expert not involved in the research, Brian Menounos of the University of Northern British Columbia, said that while glaciers have waxed and waned as a result of natural forces over the eons, the new paper and his own research underscore the fact that the recent large-scale retreat of glaciers shows humans and the greenhouse gases they produce are reshaping the planet. “Clearly, we’re implicated in many of those changes,” he said.

    See the full article here .

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  • richardmitnick 7:12 am on August 4, 2015 Permalink | Reply
    Tags: , , Global Warming   

    From Discovery: “Hopes Dim for Reversing Ocean Warming: Study” 

    Discovery News
    Discovery News

    Aug 3, 2015
    AFP

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    Technology to drain heat-trapping CO2 from the atmosphere may slow global warming, but will not reverse climate damage to the ocean on any meaningful timescale, according to research published Monday.

    A new NASA study has revealed that the ocean abyss has not warmed in the past few years. What does this mean for global warming?

    At the same time, a second study reported, even the most aggressive timetable for reducing greenhouse-gas emissions will need a big boost from largely untested carbon removal schemes to cap warming to two degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels.

    Above that threshold, say scientists, the risk of climate calamity rises sharply. Earth is currently on a 4 Celsius (7.2 Fahrenheit) trajectory.

    Both studies, coming months before 195 nations meet in Paris in a bid to forge a climate pact, conclude that deep, swift cuts in carbon dioxide (CO2) emissions are crucial.

    Planetary-scale technical fixes — sometimes called geo-engineering — have often been invoked as a fallback solution in the fight against climate change.

    But with CO2 emissions still rising, along with the global thermostat, many scientists are starting to take a hard look at which ones might be feasible.

    Research has shown that extracting massive quantities of CO2 from the atmosphere, through intensive reforestation programs or carbon-scrubbing technology, would in theory help cool the planet.

    But up to now, little was known about the long-term potential for these measures for restoring oceans, rendered overly acidic after two centuries of absorbing CO2.

    Increased acidification has already ravaged coral, and several kinds of micro-organisms essential to the ocean food chain, with impacts going all the way up to humans.

    Scientists led by Sabine Mathesius of the GEOMAR Helmholtz Center for Ocean Research in Kiel, Germany, used computer models to test different carbon-reduction scenarios, looking in each case at the impact on acidity, water temperatures and oxygen levels.

    If humanity waited a century before sucking massive amounts of CO2 out of the atmosphere, they concluded, it would still take centuries, maybe even a thousand years, before the ocean would catch up.

    In the meantime, they researchers say, corals will have disappeared, many marine species will have gone extinct and the ocean would be rife with dead spots.

    “We show that in a business-as-usual scenario, even massive deployment of CO2 removal schemes cannot reverse the substantial impacts on the marine environment — at least not within many centuries,” Mathesius said.

    Even in a scenario in which large-scale carbon removal begins in 2050 — assuming such technology is available — the ocean does not fare well.

    “Immediate and ambitious action to reduce CO2 emissions is the most reliable strategy for avoiding dangerous climate change, ocean acidification, and large-scale threats to marine ecosystems,” the researchers concluded.

    Scientists commenting on the study said it should sound an alarm.

    “The threat of ocean acidification alone justifies dramatic and rapid reduction of CO2 emissions,” said Nick Riley, a research associate at the British Geological Survey (BGS).

    The second study, led by Thomas Gasser of the Institut Pierre-Simon Laplace, near Paris, uses state-of-the-art models to measure the trade-off between reducing emissions and carbon-removing technologies.

    They show that even if nations strike a deal in Paris adhering to the most aggressive CO2-slashing pathway outlined by UN scientists, it may not be enough to keep Earth on a 2 C trajectory.

    “Our results suggest that negative emissions” — the use of carbon removing technology — “are needed even in the case of very high mitigation rates.”

    To have a chance of meeting the 2 C target, 0.5 to 3.0 gigatonnes of carbon — up to a third of total annual CO2 emissions today from industry — would need to be extracted every year starting more or less immediately, they calculate.

    The study exposes “an elephant in the room,” Riley said. ”The target to keep warming within the 2 C rise is looking increasingly unattainable.”

    See the full article here.

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  • richardmitnick 4:36 am on February 24, 2015 Permalink | Reply
    Tags: , , Giant Siberian Craters, Global Warming   

    From Siberian Times: “How global warming could turn Siberia into a giant crater ‘time bomb’” 

    Siberian Times

    The Siberian Times

    25 December 2014
    Anna Liesowska & Derek Lambie

    Scientists say there is growing evidence that rising temperatures were catalyst for massive unexplained holes in ground.

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    Scientists studying one of the massive holes on the Yamal Peninsula say there is growing evidence that rising temperatures is the main catalyst. Picture: Vladimir Pushkarev/Russian Centre of Arctic Exploration

    Global warming could leave parts of Siberia exposed to a wave of underground explosions like those behind the recent unexplained giant craters phenomenon. Scientists studying one of the massive holes on the Yamal Peninsula say there is growing evidence that rising temperatures is the main catalyst triggering the blasts. They believe warming air is melting the thick permafrost, leading to the accumulation and release of volatile ‘fire ice’ gases which then explodes to create the giant funnels. Overall temperatures in Yamal, in northwest Siberia, in the past 14 years alone have risen by at least two degrees Celsius. Any continued increase – as is predicted by meteorologists – could create the ideal conditions for more craters to be formed across the icy region, and other parts of Siberia.

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    July 2014, the first scientific expedition has just returned from the site with first probes. Pictures: Marya Zulinova, Yamal regional government’s press service

    There is already speculation that Lake Baikal, the largest and oldest freshwater lake in the world, could also be sitting on a ‘time bomb’ ready to explode. The scenic stretch of water, which snakes for 400 miles through south-east Siberia, has massive reserves of the volatile ‘fire ice’ buried under ground. A number of craters have appeared across Siberia over the past few years, with the first spotted in 2013 by helicopter pilots 20 miles from a gas extraction plant at Bovanenkov. The second was in the same permafrost region of northern Russia, and the third on the Taymyr Peninsula, to the east, in the Krasnoyarsk region. Their emergence has baffled scientists, who have carried out extensive tests including taking ice probes, sampling gas levels and examining the crater walls. A number of expeditions have taken place to the Yamal hole, the latest of which was at the beginning of November. Since then several conferences, seminars and meetings have been held by scientists and other experts to share their opinions about what caused it.

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    This new crater near the village of Nosok on Taimyr and in the Taz district, near the village of Antipayuta. Pictures: Local residents, Yamal regional government’s press service

    The latest data suggests the crater was formed at some point between October 9 and November 1, 2013. A consensus is beginning to grow that elevated levels of the crystallised ‘fire ice’ gas is causing the explosions in the same way as eruptions below the Atlantic may be behind the Bermuda Triangle phenomenon. It is thought permafrost at the sites could have one million times more methane hydrates locked inside than ordinary gas. But what is causing this gas to erupt has caused great divide, although many scientists now believe there is a link to the rising temperatures in the region. One of the first to view the site was Marina Leibman, a senior researcher at the Institute of the Earth’s Cryosphere, of the Siberian Branch of the Russian Academy of Sciences. She is convinced global warming is to blame, and told this to delegates at the recent Scientific Conference on Arctic Exploration. Dr Leibman told the Siberian Times: ‘We have agreed that in the area of Bovanenkovo there was an emission of gas and gas hydrates caused by the heating of the earth’s surface and geological features of the site. These phenomena caused the formation of crater. ‘In the last 14 years, the overall temperature in the depths of the Yamal has increased by at least two degrees Celsius. ‘In some areas of the region seasonal thawing of permafrost may affect the upper layers of ice and, under certain circumstances, cause thawing and dissociation of gas hydrates.’ She added: ‘I would argue this is a new process, which was not observed previously. It can be seen as a reaction to changes in the temperature, which releases gas, possibly hidden in the form of relic hydrate, from the upper layers of permafrost.’

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    Marina Leibman and Andrey Plekhanov making measurments at the site. Pictures: Marya Zulinova, Yamal regional government’s press service

    One expert said more eruptions could prove deadly, with estimates that the total explosive power of the craters has been the equivalent of about 11 tonnes of TNT. Larissa Kozhina, the head of the laboratory centre of hydrocarbon resources and reserves at energy firm Gazprom, said: ‘The crater at Bovanenkovo is above the gas trap, where prospective reserves are estimated at 17 billion cubic meters. What does this mean? All fields, all pipelines and railway tracks could be affected by such dangerous objects behind them and should be monitored.’ Formed in a near-perfect cylinder, the Yamal crater is slightly wider at the surface and has smooth walls, with a frozen lake at the bottom. During recent examinations of the site, thawed out permafrost was found 200metres from the top of the crater. About a third of the crater is filled with water because of its melting walls and rain, and it is thought that within three years it will be almost full. Initially it was thought that by 2024 it will be difficult to see the 40 metres wide and 50 metres deep crater at all as it will be completely submerged by a lake. But Dr Leibman told the Siberian Times that the crater may already be under water from the melting ice by next year. She said: ‘Judging by the pace, by the end of next summer it may turn into a lake. ‘I once heard a theory that deep Yamal lakes were mostly the result of emissions of gas. Then I just laughed at it. Now I take back my laughter: I think that a lot of deep lakes on Yamal were formed in this way.’

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    Scientists from ‘Gazprom VNIIGAZ’ and the Trofimuk Petroleum-Gas Geology and Geophysics Institute study the crater in September. Pictures: Gazprom

    Other scientists disagree with that theory, however, and say that the permafrost is being melted by underground heat from tectonic plates. ‘The Yamal crater is located at the intersection of tectonic faults,’ said Vladimir Olenchenko, a senior researcher in the Laboratory of Geo-electrics at the Institute of Petroleum Geology and Geophysics in Novosibirsk. ‘Despite the fact the region itself is seismically quiet area, there is an active tectonic life. Of course, it says the following: there was a slightly higher temperature, simply because heat rises from the centre of our planet via these cracks in the earth’s crust. It warmed the permafrost. ‘Or the warm stream could come from the oil and gas deposits lying under the funnel.’ There are two tectonic fault lines across the Yamal Peninsula, with one possibility being that the blow-out was caused by a deadly combination of heat leaving these rifts, a higher than normal air temperature, and the ‘fire ice’ melting. In November the Siberian Times told how scientists have been carrying out tests in the funnel to see if it could harness a new, highly efficient, gas energy source of the future. Japan, Canada and the United States have all ploughed millions of dollars into research projects to uncover and utilise global reserves of methane hydrate, as oil and coal dwindle. But now the discovery of the compound within the Siberian craters could give Russia the lead in the race to dominate the market over the next century.

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    The latest expedition to Yamal crater was initiated by the Russian Centre of Arctic Exploration in early November 2014. Pictures: Vladimir Pushkarev/Russian Centre of Arctic Exploration

    When the Yamal hole first appeared, many odd theories were put forward to explain the phenomenon, including that it was a stray missile, a meteorite or even the work of aliens. A research team from the Trofimuk Petroleum-Gas Geology and Geophysics Institute said there is evidence all the craters could be linked to the Bermuda Triangle. Explosions under the Atlantic Ocean caused by high gas hydrate emissions are thought to explain part of the mystery of ships and aircraft disappearing. Ironically the name Yamal means ‘the end of the world’, the same description applied to the Bermuda Triangle, off the Florida coastline. Further tests at the site will take place in April, if there is sufficient funding in place. Dr Leibman said: ‘To understand and describe this phenomena fully, we need to do it seriously and not in a hurry. ‘I hope that we will have opportunity to go to the funnel next year. Now we have more information and we know better about which measurements we need and which equipment we need to take.’

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  • richardmitnick 11:40 am on December 16, 2014 Permalink | Reply
    Tags: , , Global Warming,   

    From AAAS: “Greenhouse emissions similar to today’s may have triggered massive temperature rise in Earth’s past” 

    AAAS

    AAAS

    15 December 2014
    Tim Wogan

    About 55.5 million years ago, a burst of carbon dioxide raised Earth’s temperature 5°C to 8°C, which had major impacts on numerous species of plants and wildlife. Scientists analyzing ancient soil samples now say a previous burst of the greenhouse gas preceded this event, known as the Paleocene-Eocene thermal maximum (PETM), and probably triggered it. Moreover, they believe humans are pumping similar levels of carbon dioxide into the atmosphere right now, raising concerns that our own emissions may also destabilize Earth’s climate, triggering the planet to emit devastating bursts of carbon in the future.

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    This figure is a simplified, schematic representation of the flows of energy between space, the atmosphere, and the Earth’s surface, and shows how these flows combine to trap heat near the surface and create the greenhouse effect. Energy exchanges are expressed in watts per square meter (W/m2) and derived from Kiehl & Trenberth (1997). The figure does not appear clear. I would change the 195 to atmospheric radiation into space, as it does not include the 40 radiated from the surface. Complete figure: (http://www.cgd.ucar.edu/cas/abstracts/files/kevin1997_1.html)

    The sun is responsible for virtually all energy that reaches the Earth’s surface. Direct overhead sunlight at the top of the atmosphere provides 1366 W/m2; however, geometric effects and reflective surfaces limit the light which is absorbed at the typical location to an annual average of ~235 W/m2. If this were the total heat received at the surface, then, neglecting changes in albedo, the Earth’s surface would be expected to have an average temperature of -18 °C (Lashof 1989). Of the surface heat captured by the atmosphere, more than 75% can be attributed to the action of greenhouse gases that absorb thermal radiation emitted by the Earth’s surface. The atmosphere in turn transfers the energy it receives both into space (38%) and back to the Earth’s surface (62%), where the amount transferred in each direction depends on the thermal and density structure of the atmosphere. This process by which energy is recycled in the atmosphere to warm the Earth’s surface is known as the greenhouse effect and is an essential piece of Earth’s climate. Under stable conditions, the total amount of energy entering the system from solar radiation will exactly balance the amount being radiated into space, thus allowing the Earth to maintain a constant average temperature over time.
    However, recent measurements indicate that the Earth is presently absorbing 0.85 ± 0.15 W/m2 more than it emits into space (Hansen et al. 2005). An overwhelming majority of climate scientists believe that this asymmetry in the flow of energy has been significantly increased by human emissions of greenhouse gases [1]. This figure was created by Robert A. Rohde from published data and is part of the Global Warming Art project

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    Rocks from the Bighorn Basin in Wyoming were used to reconstruct Earth’s climate at the time of the Paleocene-Eocene thermal maximum. (Scott Wing, Smithsonian Institution)

    The paper implies that even if we stopped emitting carbon dioxide right now, our descendants might still face huge temperature rises, says paleoclimatologist Gabriel Bowen of the University of Utah in Salt Lake City, the lead author of the new research. “It is a possibility,” he says, “and it’s a scary one.”

    Scientists accept that a massive injection of carbon into the atmosphere caused the PETM, but they don’t agree about where the gas came from. Some researchers say it originated from the release of carbon locked up under the ocean by an undersea landslide; others blame a comet crashing into Earth, causing carbon from both the comet and Earth to be oxidized to carbon dioxide and potentially causing wildfires or burning of carbon-rich peat bogs on Earth. They also don’t know how long the release lasted, with recent estimates ranging from 10 years to 20,000 years.

    One of the best ways to measure the prehistoric release of carbon into the atmosphere is to look at the ratio of two types of carbon atoms called isotopes. Carbon has two stable isotopes: About 99% of natural carbon is carbon-12, whereas the remaining 1% is mainly the heavier carbon-13, with trace amounts of radioactive carbon-14 that decay within a few thousand years to nitrogen. Living organisms have a slight preference for the lighter isotope, so carbon derived from organic sources (such as fossil fuels) is slightly depleted in carbon-13. If that carbon gets returned to the atmosphere at a faster rate than normal, atmospheric carbon dioxide has less carbon-13 than normal. Plants taking up this carbon dioxide become even more carbon-13 depleted, and when they decompose, this depletion is recorded in the soil.

    Sedimentary rock samples that have been compacted from soils formed at the time of the PETM contain less carbon-13 than normal. Sedimentary rocks of the Bighorn Basin in Wyoming contain one of the best records of soils from this period. Geologists have studied them for more than 100 years, but to obtain samples from soils of different periods, geologists had to analyze surface rocks from different parts of the basin and try to piece together a continuous geological history. Therefore, the Bighorn Basin Coring Project, run by the University of New Hampshire, Durham, drilled approximately 1 km of core from each of three different points in the basin to give geologists three clear, continuous records of how the soils had varied over time in a particular place.

    Bowen and colleagues analyzed one of these cores, tracking the variations in carbon isotope ratios in greater detail than had been previously possible by examining surface rocks. They report online today in Nature Geoscience that in soils beneath those laid down during the main rise in temperature about 55.5 million years ago, there was a distinct drop in the proportion of carbon-13. In soils immediately on top of these, the ratio seemed to recover to its normal value. Finally, soils on top of these showed a large drop in the proportion of carbon-13 corresponding to the PETM itself.

    So what was going on? The researchers concluded that there must have been two separate releases of carbon. The first, smaller release, about 2000 years before the main temperature rise, was followed by a recovery to normal climatic conditions. Later, a second, larger pulse caused the main event. “I’m fairly convinced that they’re related,” Bowen says. “We see nothing remotely similar during the many hundreds of thousands of years before this event. To have within a few thousand years these two major carbon isotope shifts and have that be circumstantial would be quite remarkable.”

    The researchers used climate models to investigate how the initial, smaller heating could have triggered the later surge in temperature. They estimate that the first thermal pulse is likely to have warmed Earth’s atmosphere by 2°C to 3°C, but that the atmospheric temperature would have gradually returned to normal as the heat was absorbed into the deep ocean. However, when that heat finally reached the ocean floor, it might have melted methane ices called clathrates, releasing the methane into the ocean and allowing it to make its way into the atmosphere. As a greenhouse gas, methane is 21 times more potent than carbon dioxide, so a sudden spike in methane emissions could lead to huge climate change.

    “The connection between these two pulses is something that it’s going to be really important to get a handle on,” Bowen says. The researchers believe the rate at which carbon dioxide escaped into the atmosphere during both bursts is unlikely to have been greater than the rate at which humans are emitting it now, and it may have been considerably lower. “Carbon release back then looked a lot like human fossil fuel emissions today,” Bowen says. “So we might learn a lot about the future from changes in climate, plants, and animal communities 55.5 million years ago.”

    “We think this is really good news for our contention that the release of carbon was very fast,” says marine geologist James Wright of Rutgers University, New Brunswick, an advocate of the comet impact hypothesis.

    Wright is not convinced, however, about the importance of the first pulse in triggering the second. He suggests that the most logical interpretation of the apparent cooling after the first pulse is that its significance was less than Bowen’s group believes, with limited effect on the overall ocean temperature, and that not just the atmosphere but rather the entire planet quickly returned to normal. “If that’s the case, then the first has nothing to do with the second,” Wright says. That, in turn, would require an alternative explanation for the PETM such as a comet impact.

    See the full article here.

    The American Association for the Advancement of Science is an international non-profit organization dedicated to advancing science for the benefit of all people.

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  • richardmitnick 2:09 pm on December 11, 2014 Permalink | Reply
    Tags: , Global Warming,   

    From NOVA: “Volcanoes May Be Masking the Severity of Global Warming” 

    PBS NOVA

    NOVA

    Thu, 11 Dec 2014
    Christina Couch

    Global warming continues to heat up the earth, but volcanoes are keeping us just a little cooler.

    A new paper published in Geophysical Research Letters shows that volcanic eruptions may be part of the reason why the earth isn’t heating up quite as fast as climate models predict. Sneaky sulfur dioxide emissions coming from smaller volcanoes that weren’t previously factored into climate models are temporarily cooling surface temperatures, said research from MIT atmospheric scientist David Ridley.

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    Alaska’s Augustine Volcano Jan 12, 2006

    “If an eruption is powerful enough, the sulfur dioxide can reach the upper atmosphere, the stratosphere, where it forms literally liquid sulfuric acid droplets,” said Benjamin Santer, a research scientist at Lawrence Livermore National Laboratory and co-author on the study. “Those droplets reflect some fraction of incoming sunlight back to space, preventing that sunlight from penetrating deeper into the atmosphere. That’s the primary cooling mechanism.”

    According to Santer and Ridley’s research, that light-refracting cooling effect is strong enough to bring global temperatures down anywhere from 0.09˚ to 0.22˚ F since 2000. Unfortunately the cooling won’t do much to counteract global warming in the long term—Ridley said that the amount of sulfur dioxide released in a small eruption generally dissipates after about one year. But these emissions may be part of the reason why over the last ten to 15 years, average global temperatures haven’t increased as rapidly as they have in decades past. The Intergovernmental Panel on Climate Change estimates that average worldwide temperatures are currently increasing at about one-third the rate that they were between 1951 and 2012.

    “I think there’s quite a good case now that volcanoes are at least able to explain about a third of that,” Ridley said.

    On top of providing volcano emissions data, Ridley’s study also offers scientists a new way to explore the lower stratosphere. Both current research and climate models rely on data derived from satellite observations to measure what’s happening in the stratosphere. That works well until around nine to ten miles above the earth’s surface, where clouds contaminate the data and make it difficult to discern exactly what’s happening. The problem becomes even more complex around the poles where the stratosphere dips lower than it does in the tropics and creates “this kind of wedge of stratosphere that we’re missing when just using the satellites” Ridley said.

    Instead of making estimates based on satellite observations alone, Ridley’s team also used data from a balloon-borne particle counter and from measurement devices on the ground. These included four lidar systems, which measure atmospheric particles using laser light pulses, and data from a series of robotic solar photometers called AERONET that use sunlight to measure how effective aerosol particles are at blocking light. The ground and air-based measurements gave researchers a clearer picture of the chemical makeup of the lower stratosphere.

    “Even though it’s a small part of the atmosphere that we were able to include that hadn’t been included before, it probably has a majority of the aerosols that are important” in the short term, said Ryan R. Neely III, a co-author on the study and lecturer of observational atmospheric science at the University of Leeds.

    Alan Robock, a climate scientist who was not involved in the study but was quoted in the journal’s press release, commended Ridley’s team for using ground and air-based instruments to examine the lower stratosphere in a way that satellite data simply can’t. He said that the new observational methods can potentially help scientists make better climate predictions and create more accurate models in the future.

    Creating accurate climate models hasn’t been easy in the middle of a so-called global warming pause or “hiatus,” especially one that’s controversial among scientists. While some attribute the slowdown to the ocean storing heat, others chalk it up to solar cycles or temperature fluctuations from El Niño and La Niña weather patterns.

    “The hiatus, the pause, it’s a little misleading,” said Todd Sanford, a climate scientist with Climate Central. “We’re still setting global [temperature] records. Really what this is talking about is how quickly temperatures are increasing, not that they have stopped increasing.”

    Even with the pause, global warming is still a major environmental problem, one so large that some researchers are investigating whether a strategy like spraying sulfur dioxide into the stratosphere to mimic the cooling effects from volcanoes is a viable temporary solution.

    “We know that if this were to be done, we could get fairly rapid reductions in temperatures but there are issues with it,” Sanford said. “You’re masking the effect of CO2 in some ways. That’s good as long as you’re doing it, but if for any reason you stopped injecting these particles up into the atmosphere, you’re now very quickly unmasking all of that CO2 warming. You’d get all of that warming back. It’s one of these things where if you start it and you’re not doing anything else on CO2, you’ve got to keep it going.”

    Besides, Sanford added, simply cooling the atmosphere without reducing CO2 won’t address other problems caused by carbon, like increasing ocean acidification.

    Sulfur dioxide injections could also deteriorate the ozone, produce uneven temperature and precipitation patterns, completely obscure our view of the sky, and create global political issues as the world decides “what temperature to set the thermostat” Robock said. He added that the technology to execute this type of geoengineering doesn’t yet exist, though others like Harvard climate scientist David Keith argue that it does. Even if we were able to get a critical mass of sulfuric acid into the stratosphere, there’s no way to control it once its there.

    “If you have an existing cloud up there and you start spraying more sulfur, theory tells us the particles will grow and you’ll get larger particles rather than more particles and they’ll be much less effective at scattering sunlight,” Robock said. “They’ll also fall out faster so you have to put a lot more up there.”

    Kicking our carbon habit is the real solution to global warming, Robock added, but until that happens, creating more accurate climate models can help us better understand how the atmosphere is changing.

    Ridley warns against the dangers of placing too much emphasis on volcanic cooling. While volcanoes are playing a small but significant role in keeping rising temperatures a little in check, sulfur dioxide cooling isn’t a safeguard against the effects of global warming. “This is really just a bit of an offset on the warming rather than a change in the expected trend on warming,” he said. Besides, he added, no good global hiatus lasts forever. “We’ve got no reason to believe that that will continue.”

    See the full article here.

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  • richardmitnick 8:42 am on August 22, 2014 Permalink | Reply
    Tags: , , Global Warming   

    From Astrobiology: “Cause of global warming hiatus found deep in the Atlantic Ocean” 

    Astrobiology Magazine

    Astrobiology Magazine

    Aug 22, 2014
    Hannah Hickey, University of Washington

    Following rapid warming in the late 20th century, this century has so far seen surprisingly little increase in the average temperature at the Earth’s surface. At first this was a blip, then a trend, then a puzzle for the climate science community.

    More than a dozen theories have now been proposed for the so-called global warming hiatus, ranging from air pollution to volcanoes to sunspots. New research from the University of Washington shows that the heat absent from the surface is plunging deep in the north and south Atlantic Ocean, and is part of a naturally occurring cycle. The study is published Aug. 22 in Science.

    Subsurface ocean warming explains why global average air temperatures have flatlined since 1999, despite greenhouse gases trapping more solar heat at the Earth’s surface.

    “Every week there’s a new explanation of the hiatus,” said corresponding author Ka-Kit Tung, a UW professor of applied mathematics and adjunct faculty member in atmospheric sciences. “Many of the earlier papers had necessarily focused on symptoms at the surface of the Earth, where we see many different and related phenomena. We looked at observations in the ocean to try to find the underlying cause.”

    The results show that a slow-moving current in the Atlantic, which carries heat between the two poles, sped up earlier this century to draw heat down almost a mile (1,500 meters). Most of the previous studies focused on shorter-term variability or particles that could block incoming sunlight, but they could not explain the massive amount of heat missing for more than a decade.

    “The finding is a surprise, since the current theories had pointed to the Pacific Ocean as the culprit for hiding heat,” Tung said. “But the data are quite convincing and they show otherwise.”

    Tung and co-author Xianyao Chen of the Ocean University of China, who was a UW visiting professor last year, used recent observations of deep-sea temperatures from Argo floats that sample the water down to 6,500 feet (2,000 meters) depth. The data show an increase in heat sinking around 1999, when the rapid warming of the 20th century stopped.

    graph
    (Top) Global average surface temperatures, where black dots are yearly averages. Two flat periods (hiatus) are separated by rapid warming from 1976-1999. (Middle) Observations of heat content, compared to the average, in the north Atlantic Ocean. (Bottom) Salinity of the seawater in the same part of the Atlantic. Higher salinity is seen to coincide with more ocean heat storage. K. Tung / Univ. of Washington

    “There are recurrent cycles that are salinity-driven that can store heat deep in the Atlantic and Southern oceans,” Tung said. “After 30 years of rapid warming in the warm phase, now it’s time for the cool phase.”

    Rapid warming in the last three decades of the 20th century, they found, was roughly half due to global warming and half to the natural Atlantic Ocean cycle that kept more heat near the surface. When observations show the ocean cycle flipped, in about 2000, the current began to draw heat deeper into the ocean, working to counteract human-driven warming.

    The cycle starts when saltier, denser water at the surface northern part of the Atlantic, near Iceland, causes the water to sink. This changes the speed of the huge current in the Atlantic Ocean that circulates heat throughout the planet.

    “When it’s heavy water on top of light water, it just plunges very fast and takes heat with it,” Tung said. Recent observations at the surface in the North Atlantic show record-high saltiness, Tung said, while at the same time, deeper water in the North Atlantic shows increasing amounts of heat.

    The oscillations have a natural switch. During the warm period, faster currents cause more tropical water to travel to the North Atlantic, warming both the surface and the deep water. At the surface this warming melts ice. This slowly makes the surface water there less dense and after a few decades puts the brakes on the circulation, setting off a 30-year cooling phase.

    The authors dug up historical data to show that the cooling in the three decades between 1945 to 1975 – which caused people to worry about the start of an Ice Age – was during a cooling phase. (It was thought to have been caused by air pollution.) Earlier records in Central England show the 40- to 70-year cycle goes back centuries, and other records show it has existed for millennia.

    Changes in Atlantic Ocean circulation historically meant roughly 30 warmer years followed by 30 cooler years. Now that it is happening on top of global warming, however, the trend looks more like a staircase.

    This explanation implies that the current slowdown in global warming could last for another decade, or longer, and then rapid warming will return. But Tung emphasizes it’s hard to predict what will happen next.

    A pool of freshwater from melting ice now sitting in the Arctic Ocean, for example, could overflow into the North Atlantic to upset the cycle.

    “We are not talking about a normal situation because there are so many other things happening due to climate change,” Tung said.

    See the full article here.

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