Tag Archive: Geophysical Research Letters


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Climate change increasing massive wildfires in West

Climate change increasing massive wildfires in West

Credit: Draysen Brooks Bechard

Wildfire near Wenatchee, 2013.

by Doyle Rice, USA TODAY

Posted on April 19, 2014 at 11:06 AM

Updated today at 11:09 AM

 

Massive wildfires are on the increase in the Western US due to rising temperatures and worsening drought from climate change, and the trend could continue in the decades to come, new research suggests.

Overall, the number of large wildfires increased by a rate of seven fires a year from 1984 to 2011, while the total area damaged by fire increased at a rate of nearly 90,000 acres per year, according to the study, published this week in Geophysical Research Letters, a journal of the American Geophysical Union (AGU).

The study comes against the backdrop of what could to be a disastrous year for fires in the West, especially drought-plagued California, which even saw fires in the normally quiet month of January.

Though relatively calm this week, “Expect dry and windy conditions to develop over the Southwest Tuesday and Wednesday,” according to a forecast Friday from the National Interagency Fire Center in Boise. By May, “Above normal significant fire potential will expand over portions of Southern, Central and Northern California,” the NIFC predicted earlier this month.

 

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File:Boomstronken.jpg

Description  :  Boomstronken; foto door Fruggo, juni 2003.

Attribution: Fruggo from nl

Creative Commons Attribution-Share Alike 3.0 Unported

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New Research Shows Tree Roots Regulate CO2, Keep Climate Stable

Climate News Network | February 19, 2014 8:30 am

The argument, put forward by a team from Oxford and Sheffield Universities in the journal Geophysical Research Letters, begins with temperature. Warmer climates mean more vigorous tree growth and more leaf litter, and more organic content in the soil. So the tree’s roots grow more vigorously, said Dr. Christopher Doughty of Oxford and colleagues.

They get into the bedrock, and break up the rock into its constituent minerals. Once that happens, the rock starts to weather, combining with carbon dioxide. This weathering draws carbon dioxide out of the atmosphere, and in the process cools the planet down a little. So mountain ecosystems—mountain forests are usually wet and on conspicuous layers of rock—are in effect part of the global thermostat, preventing catastrophic overheating.

The tree is more than just a sink for carbon, it is an agency for chemical weathering that removes carbon from the air and locks it up in carbonate rock.

That mountain weathering and forest growth are part of the climate system has never been in much doubt: the questions have always been about how big a forest’s role might be, and how to calculate its contribution.

Keeping climate stable

U.S. scientists recently studied the rainy slopes of New Zealand’s Southern Alps to begin to put a value on mountain ecosystem processes. Dr. Doughty and his colleagues measured tree roots at varying altitudes in the tropical rain forests of Peru, from the Amazon lowlands to 3,000 meters of altitude in the higher Andes.

They measured the growth to 30 cm below the surface every three months and did so for a period of years. They recorded the thickness of the soil’s organic layer, and they matched their observations with local temperatures, and began to calculate the rate at which tree roots might turn Andean granite into soil.

Then they scaled up the process, and extended it through long periods of time. Their conclusion: that forests served to moderate temperatures in a much hotter world 65 million years ago.

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Old Faithful’s hidden cavern discovered

By

Chiffre

Posted on April 23, 2013

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The Watchers

A new study of the Yellowstone National Park geyser shows that the underground plumbing of the Old Faithful looks like a bagpipe. Scientists report, in study published online March 30, 2013 in the journal Geophysical Research Letters, that a big chamber is positioned about 15 meters (50 feet) underground, located southwest of Old Faithful.

The research presents another strong argument against the long-standing idea that big geysers erupt from long, narrow tubes. The researchers who uncovered new evidence of a chamber suspect that it stores the pressurized near-boiling water, steam, and other gases that propel Old Faithful’s eruptions

Old Faithful got its name because of its regular eruptions, which occur every 92 minutes on average. Almost immediately after an eruption, there’s a 15-minute recharge period with low water levels. After that for about 50 minutes, water levels rise and seismic activity increases. The cavern never fully empties, but as steam bubbles fill it, they can oscillate water in the conduit, eventually producing a strong steam explosion. This bubble trap is what makes Old Faithful splash with smaller eruptions before releasing its full force.

The graph of Old Faithful Geyser  shows the estimated shape of a subterranean cavity beneath the geyser (Credit: GeoSpace )

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March 2, 2013

[ Watch the Video: What is Global Warming ]

redOrbit Staff & Wire Reports – Your Universe Online

Global warming was slowed between 2000 and 2010 because of sulfur dioxide spewed forth by volcanoes, researchers from the University of Colorado Boulder (CU-Boulder) and the National Oceanic and Atmospheric Administration (NOAA) claim in a new study.

Some experts had blamed China and India for the phenomenon, as both countries increased their industrial sulfur dioxide emissions by an estimated 60 percent during that decade. The new findings essentially exonerates those two Asian nations, lead author Ryan Neely of the Cooperative Institute for Research in Environmental Sciences (CIRES) said Friday in a statement.

Writing in the online edition of the journal Geophysical Research Letters, Neely and his colleagues report that increases in stratospheric aerosols over the past 13 years have counteracted nearly one-fourth of the temperature increased that have been blamed on human greenhouse gas emissions.

Portions of sulfur dioxide emissions from the planet’s surface ultimately rise to as much as 20 miles into the stratosphere, where chemical reactions cause them to be changed into sulfuric acid and water that reflect sunlight back into space and keep the planet cool.

Neely and researchers from CU-Boulder, the NOAA, MIT, NASA’s Langley Research Center, and the National Center for Atmospheric Research (NCAR) reported that emissions caused by volcanoes of “small to moderate” size caused global warming to slow during that 10-year period.

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WATER WORLD

by Staff Writers
Irvine CA (SPX) Feb 04, 2013


File image.

Agricultural irrigation in California’s Central Valley doubles the amount of water vapor pumped into the atmosphere, ratcheting up rainfall and powerful monsoons across the interior Southwest, according to a new study by UC Irvine scientists.

Moisture on the vast farm fields evaporates, is blown over the Sierra Nevada and dumps 15 percent more than average summer rain in numerous other states. Runoff to the Colorado River increases by 28 percent, and the Four Corners region experiences a 56 percent boost in runoff. While the additional water supply can be a good thing, the transport pattern also accelerates the severity of monsoons and other potentially destructive seasonal weather events.

“If we stop irrigating in the Valley, we’ll see a decrease in stream flow in the Colorado River basin,” said climate hydrologist Jay Famiglietti, senior author on the paper, which will be published online in the journal Geophysical Research Letters.

 

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Crossroads News : Changes In The World Around Us And Our Place In It

Pollution

 

FARM NEWS

More Potent than CO2, N2O Levels in California May be Nearly Three Times Higher Than Previously Thought

by Staff Writers
Berkeley CA (SPX)


This map shows the amount of nitrous oxide emissions in California (in nanomoles per square meter per second). The “x” represents the location of the measurement tower in Walnut Grove, CA.

Using a new method for estimating greenhouse gases that combines atmospheric measurements with model predictions, Lawrence Berkeley National Laboratory (Berkeley Lab) researchers have found that the level of nitrous oxide, a potent greenhouse gas, in California may be 2.5 to 3 times greater than the current inventory.

At that level, total N2O emissions-which are believed to come primarily from nitrogen fertilizers used in agricultural production-would account for about 8 percent of California’s total greenhouse gas emissions.

The findings were recently published in a paper titled “Seasonal variations in N2O emissions from central California” in Geophysical Research Letters. Earlier this year, using the same methodology, the researchers found that levels of methane, another potent greenhouse gas, in California may be up to 1.8 times greater than previous estimates.

“If our results are accurate, then it suggests that N2O makes up not 3 percent of California’s total effective greenhouse gases but closer to 10 percent,” said Marc Fischer, lead researcher on both studies.

“And taken together with our previous estimates of methane emissions, that suggests those two gases may make up 20 to 25 percent of California’s total emissions. That’s starting to become roughly comparable to emissions from fossil fuel CO2.”

Accurate estimates of the California’s greenhouse gas emissions are important as the state works to reduce emissions to 1990 levels by 2020, as mandated by a law known as AB 32. The vast majority of the reduction efforts have been focused on CO2.

Nitrous oxide, better known as laughing gas, is an especially potent greenhouse gas because it traps far more infrared radiation than both carbon dioxide and methane. “It’s present in the atmosphere at tiny concentrations-one-thousandth that of CO2-but it is very potent,” Fischer said. “It has a global warming potential of approximately 300, meaning it is 300 times more active than CO2 per unit mass. And it’s 10 to 15 times more potent than methane.”

Worldwide levels of N2O have been rising rapidly for decades, and the major culprit was recently confirmed to be the heavy use of nitrogen fertilizers to grow the world’s food. Other less significant sources of N2O emissions include wetlands, animal and industrial waste and automobiles.

The standard method for estimating emissions levels has been to do what is called a “bottom-up inventory.” This process involves listing all the activities that emit N2O, assigning an emission factor for each activity, then tallying up the emissions. However, this method can result in large uncertainties because of the way N2O is produced.

“The biogeochemical processes that produce N2O are sensitive to environmental conditions and very small changes in things like temperature, moisture, the type of soil and when the fertilizer is applied,” Fischer said.

“All those factors can result in big differences in the amount of N2O that’s produced. If you try to use a single number for a given patch of land, you’re almost certainly going to get a variable result.”

While there are models that try to capture these factors, “it is still likely the numbers are going to have relatively large uncertainties, especially compared to thing like burning fossil fuels to make CO2, where pretty much every mole of carbon becomes CO2,” Fischer said.

The method that Fischer and his colleagues describe in their paper compares measurements taken from a 2,000-foot tower in Walnut Grove, California to model predictions of expected N2O levels based on the bottom-up inventory to arrive at the new estimate.

“This is the first study of its kind to look at a full annual cycle of emissions-actually it’s two years-from a large region of California that includes the sources that we believe are most important,” Fischer said. “In general, we found that the measured signals were much bigger than the predicted signals.”

WHITE OUT

 
by Staff Writers
Paris (ESA)


Time series of Northern Hemisphere June snow cover (red), June sea-ice extent (black) and September sea-ice extent (grey). Thick lines denote five-year running mean. Relative to a 1979-2000 baseline, June snow cover – also known as ‘snow areal extent’ – has declined by 17.6%, whereas September sea-ice has declined by 13.0%. Credits: C. Derksen and R. Brown, Environment Canada (Data from the US National Snow and Ice Data Center and Rutgers University Global Snow Lab)

Santa Claus may someday need wheels for his sleigh – satellites show a decreasing amount of snow in the Northern Hemisphere. A new analysis of snow cover observed by satellites shows record lows in Eurasia for June each year since 2008. In addition, three of the past five years have seen record low cover in North America.

This is the lowest June snow extent since satellite observations began some 45 years ago. June snow cover is found to be falling much faster than expected from climate models, and is disappearing even quicker than summertime Arctic sea-ice.

These results, published in Geophysical Research Letters in October and based on snow chart data from the US National Oceanic and Atmospheric Administration (NOAA), are consistent with indications of a decline in monthly-average snow mass, published last year as part of ESA’s GlobSnow project.

The results show that the maximum amount of snow across the Northern Hemisphere is slowly falling, while spring snow – particularly at high latitudes – is melting significantly earlier.

GlobSnow produced a long time-series of snow mass from 1979 to 2012, as well as a time-series of snow cover from 1995 to 2012.

Crossroads News : Changes In The World Around Us And Our Place In It

 

 

Anthropology & Climate Change

 

 

Wynne Parry, LiveScience Senior Writer

 

A temple in Tikal, one of the Mayan city states.

A temple in Tikal, one of the Mayan city states.
CREDIT: Zap Ichigo, Shutterstock

The city states of the ancient Mayan empire flourished in southern Mexico and northern Central America for about six centuries. Then, around A.D. 900 Mayan civilization disintegrated.

Two new studies examine the reasons for the collapse of the Mayan culture, finding the Mayans themselves contributed to the downfall of the empire.

Scientists have found that drought played a key role, but the Mayans appear to have exacerbated the problem by cutting down the jungle canopy to make way for cities and crops, according to researchers who used climate-model simulations to see how much deforestation aggravated the drought.

“We’re not saying deforestation explains the entire drought, but it does explain a substantial portion of the overall drying that is thought to have occurred,” said the study’s lead author Benjamin Cook, a climate modeler at Columbia University’s Lamont-Doherty Earth Observatory and the NASA Goddard Institute for Space Studies, in a statement. [Dry and Dying: Images of Drought]

Using climate-model simulations, he and his colleagues examined how much the switch from forest to crops, such as corn, would alter climate. Their results, detailed online in the journal Geophysical Research Letters, suggested that when deforestation was at its maximum, it could account for up to 60 percent of the drying. (The switch from trees to corn reduces the amount of water transferred from the soil to the atmosphere, which reduces rainfall.)

Other recent research takes a more holistic view.

“The ninth-century collapse and abandonment of the Central Maya Lowlands in the Yucatán peninsular region were the result of complex human–environment interactions,” writes this team in a study published Monday (Aug 20) in the journal Proceedings of the National Academy of Sciences.

The team, led by B.L. Turner, a social scientist at Arizona State University, concurs that by clearing the forest, the Mayans may have aggravated a natural drought, which spiked about the time the empire came to an end and population declined dramatically.

But this is just one contributing factor to their demise, Turner and colleagues write, pointing out that the reconfiguration of the landscape may also have led to soil degradation. Other archaeological evidence points to a landscape under stress, for instance, the wood of the sapodilla tree, favored as construction beams, was no longer used at the Tikal and Calakmul sites beginning in A.D. 741. Larger mammals, such as white-tailed deer, appear to have declined at the end of empire.

Social and economic dynamics also contributed. Trade routes shifted from land transit across the Yucatán Peninsula to sea-born ships. This change may have weakened the city states, which were contending with environmental changes. Faced with mounting challenges, the ruling elites, a very small portion of the population, were no longer capable of delivering what was expected of them, and conflict increased.

“The old political and economic structure dominated by semidivine rulers decayed,” the team writes. “Peasants, artisan – craftsmen, and others apparently abandoned their homes and cities to find better economic opportunities elsewhere in the Maya area.”

Follow Wynne Parry on Twitter @Wynne_Parry or LiveScience @livescience. We’re also on Facebook & Google+.