 |
|
Post-pandemic reforestation in New World helped trigger Little Ice Age, Stanford researchers say
December 18, 2008The power of viruses is well documented in human history. Swarms of little viral Davids have repeatedly laid low the great Goliaths of human civilization, most famously in the devastating pandemics that swept the New World during European conquest and settlement.
In recent years, there has been growing evidence for the hypothesis that the effect of the pandemics in the Americas wasn't confined to killing indigenous peoples. Global climate appears to have been altered as well.
Stanford University researchers have conducted a comprehensive analysis of data detailing the amount of charcoal contained in soils and lake sediments at the sites of both pre-Columbian population centers in the Americas and in sparsely populated surrounding regions. They concluded that reforestation of agricultural lands-abandoned as the population collapsed-pulled so much carbon out of the atmosphere that it helped trigger a period of global cooling, at its most intense from approximately 1500 to 1750, known as the Little Ice Age.
"We estimate that the amount of carbon sequestered in the growing forests was about 10 to 50 percent of the total carbon that would have needed to come out of the atmosphere and oceans at that time to account for the observed changes in carbon dioxide concentrations," said Richard Nevle, visiting scholar in the Department of Geological and Environmental Sciences at Stanford. Nevle and Dennis Bird, professor in geological and environmental sciences, presented their study at the annual meeting of the American Geophysical Union on Dec. 17, 2008.
Nevle and Bird synthesized published data from charcoal records from 15 sediment cores extracted from lakes, soil samples from 17 population centers and 18 sites from the surrounding areas in Central and South America. They examined samples dating back 5,000 years.
What they found was a record of slowly increasing charcoal deposits, indicating increasing burning of forestland to convert it to cropland, as agricultural practices spread among the human population-until around 500 years ago: At that point, there was a precipitous drop in the amount of charcoal in the samples, coinciding with the precipitous drop in the human population in the Americas.
To verify their results, they checked their fire histories based on the charcoal data against records of carbon dioxide concentrations and carbon isotope ratios that were available.
"We looked at ice cores and tropical sponge records, which give us reliable proxies for the carbon isotope composition of atmospheric carbon dioxide. And it jumped out at us right away," Nevle said. "We saw a conspicuous increase in the isotope ratio of heavy carbon to light carbon. That gave us a sense that maybe we were looking at the right thing, because that is exactly what you would expect from reforestation."
During photosynthesis, plants prefer carbon dioxide containing the lighter isotope of carbon. Thus a massive reforestation event would not only decrease the amount of carbon dioxide in the atmosphere, but would also leave carbon dioxide in the atmosphere that was enriched in the heavy carbon isotope.
Other theories have been proposed to account for the cooling at the time of the Little Ice Age, as well as the anomalies in the concentration and carbon isotope ratios of atmospheric carbon dioxide associated with that period.
Variations in the amount of sunlight striking the Earth, caused by a drop in sunspot activity, could also be a factor in cooling down the globe, as could a flurry of volcanic activity in the late 16th century.
But the timing of these events doesn't fit with the observed onset of the carbon dioxide drop. These events don't begin until at least a century after carbon dioxide in the atmosphere began to decline and the ratio of heavy to light carbon isotopes in atmospheric carbon dioxide begins to increase.
Nevle and Bird don't attribute all of the cooling during the Little Ice Age to reforestation in the Americas.
"There are other causes at play," Nevle said. "But reforestation is certainly a first-order contributor."
Stanford University
"We estimate that the amount of carbon sequestered in the growing forests was about 10 to 50 percent of the total carbon that would have needed to come out of the atmosphere and oceans at that time to account for the observed changes in carbon dioxide concentrations," said Richard Nevle, visiting scholar in the Department of Geological and Environmental Sciences at Stanford. Nevle and Dennis Bird, professor in geological and environmental sciences, presented their study at the annual meeting of the American Geophysical Union on Dec. 17, 2008.
Nevle and Bird synthesized published data from charcoal records from 15 sediment cores extracted from lakes, soil samples from 17 population centers and 18 sites from the surrounding areas in Central and South America. They examined samples dating back 5,000 years.
What they found was a record of slowly increasing charcoal deposits, indicating increasing burning of forestland to convert it to cropland, as agricultural practices spread among the human population-until around 500 years ago: At that point, there was a precipitous drop in the amount of charcoal in the samples, coinciding with the precipitous drop in the human population in the Americas.
To verify their results, they checked their fire histories based on the charcoal data against records of carbon dioxide concentrations and carbon isotope ratios that were available.
"We looked at ice cores and tropical sponge records, which give us reliable proxies for the carbon isotope composition of atmospheric carbon dioxide. And it jumped out at us right away," Nevle said. "We saw a conspicuous increase in the isotope ratio of heavy carbon to light carbon. That gave us a sense that maybe we were looking at the right thing, because that is exactly what you would expect from reforestation."
During photosynthesis, plants prefer carbon dioxide containing the lighter isotope of carbon. Thus a massive reforestation event would not only decrease the amount of carbon dioxide in the atmosphere, but would also leave carbon dioxide in the atmosphere that was enriched in the heavy carbon isotope.
Other theories have been proposed to account for the cooling at the time of the Little Ice Age, as well as the anomalies in the concentration and carbon isotope ratios of atmospheric carbon dioxide associated with that period.
Variations in the amount of sunlight striking the Earth, caused by a drop in sunspot activity, could also be a factor in cooling down the globe, as could a flurry of volcanic activity in the late 16th century.
But the timing of these events doesn't fit with the observed onset of the carbon dioxide drop. These events don't begin until at least a century after carbon dioxide in the atmosphere began to decline and the ratio of heavy to light carbon isotopes in atmospheric carbon dioxide begins to increase.
Nevle and Bird don't attribute all of the cooling during the Little Ice Age to reforestation in the Americas.
"There are other causes at play," Nevle said. "But reforestation is certainly a first-order contributor."
Stanford University
Carbon Dioxide Current Events and Carbon Dioxide News RSSChemists describe solar energy progress and challenges, including the 'artificial leaf'
Scientists are making progress toward development of an "artificial leaf" that mimics a real leaf's chemical magic with photosynthesis - but instead converts sunlight and water into a liquid fuel such as methanol for cars and trucks.
Texas A&M prof to predict weather on Mars
Is there such a thing as "weather" on Mars? There are some doubts, considering the planet's atmosphere is only 1 percent as dense as that of the Earth.
Report on US-China collaboration on carbon capture and sequestration
Lawrence Livermore National Laboratory's Julio Friedmann, in collaboration with the Center for American Progress, the Asia Society Center and with partner Monitor Group, today released the report, "A Roadmap for U.S.-China Collaboration on Carbon Capture and Sequestration."
Study gives clearer picture of how land-use changes affect U.S. climate
Researchers say regional surface temperatures can be affected by land use, suggesting that local and regional strategies, such as creating green spaces and buffer zones in and around urban areas, could be a tool in addressing climate change.
Laser etching safe alternative for labeling grapefruit
Laser labeling of fruit and vegetables is a new, patented technology in which a low-energy carbon dioxide laser beam is used to label, or "etch" information on produce, thereby eliminating the need for common sticker-type labels.
Iron controls patterns of nitrogen fixation in the Atlantic
Scientists including researchers from the National Oceanography Centre, Southampton and the University of Essex have discovered that interactions between iron supply, transported through the atmosphere from deserts, and large-scale oceanic circulation control the availability of a crucial nutrient, nitrogen, in the Atlantic.
North America automobile sector bottom of 'world sustainability league'
The study, entitled Sustainable Value in Automobile Manufacturing, looks at the sustainability performance of 17 leading car manufacturers worldwide between 1999 and 2007.
Interactions with aerosols boost warming potential of some gases
For decades, climate scientists have worked to identify and measure key substances -- notably greenhouse gases and aerosol particles -- that affect Earth's climate.
Volcanoes played pivotal role in ancient ice age, mass extinction
Researchers here have discovered the pivotal role that volcanoes played in a deadly ice age 450 million years ago. Perhaps ironically, these volcanoes first caused global warming -- by releasing massive amounts of carbon dioxide into the atmosphere. When they stopped erupting, Earth's climate was thrown off balance, and the ice age began.
Ocean acidification may contribute to global shellfish decline
Relatively minor increases in ocean acidity brought about by high levels of carbon dioxide have significant detrimental effects on the growth, development, and survival of hard clams, bay scallops, and Eastern oysters, according to researchers at Stony Brook University's School of Marine and Atmospheric Sciences.
More Carbon Dioxide Current Events and Carbon Dioxide News Articles
 |
First Alert CO600 Plug In Carbon Monoxide Alarm by First Alert Carbon monoxide (CO) is the leading cause of accidental poisoning deaths in America, yet many people don't know they are suffering from CO poisoning until its too late. Since symptoms of CO poisoning are like the flu, you might not even know you're in danger at first. That's why a carbon monoxide alarm is an excellent way to protect your family. It can detect the CO you can't see, smell or taste in the air. The First Alert CO600 carbon monoxide alarm uses an electrochemical carbon monoxide sensor-the most accurate technology available. Installation is as simple as plugging it in to any wall outlet. The test/silence button both silences a non-threatening alarm and allows you to test the unit's functionality. The unit monitors and re-alarms if carbon monoxide levels persist sounding a... |
 |
Carbon Dioxide Recovery and Utilization by M. Aresta (Editor) Text provides a resource on the carbon dioxide sources and market at the European Union level, with reference to the world situation. For scientists and professionals. |
 |
Indoor Air Quality Meter - CO2, Temperature, Relative Humidity by SenseLife The SenseLife CO2 Monitor lets you quickly, accurately, and inexpensively test CO2 levels around your home. Move it from room to room to test CO2 levels in your house. It can reveal if your home's heating, ventilation, and air conditioning system is operating properly. High CO2 levels indicate inadequate or closed return air ducts. Low CO2 levels indicate too much fresh air and wasted heating or cooling energy. In addition to its CO2 meter, the TIM8 has an accurate digital thermometer and relative humidity indicator. Use it to test your child's bedrooms. Low humidity in the winter can lead to nosebleeds, coughs, and sore throats. High humidity in the summer can result in mold and even structural damage. Do you own a greenhouse? Increasing CO2 makes flowering plants, vegetables, and... |
 |
First Alert Smoke and Carbon Monoxide Alarm - SC01CN3 by First Alert First Alert SCO1CN3 smoke and carbon monoxide detector uses ionization method of smoke detection. It features a test button and a silence button that temporarily quiets both the carbon monoxide and smoke alarms. When battery is low, the warning "chirp" and light flashes. The alarm makes different horn sounds and light flash patterns for carbon monoxide and smoke. |
 |
Kidde 900-0107 Plug-In Carbon Monoxide Alarm by Kidde Safety 110V Non-Digital AC Carbon Monoxide Alarm With Direct Plug Alarm Only 85 Decibel Alarm Test Reset Button To Reset Alarm Advanced Electrochemical Sensor 5 Year Warranty UL Listed To 2,034 Standard Clam Shell |
 |
Fire Extinguisher Carbon Dioxide 5 Lb. by Global Industrial KIDDE CARBON DIOXIDE EXTINGUISHER Effective for Class B and C fires. Environmentally safe, Co2 gas dissipates quickly leaving no residue and won't contaminate food, valuable materials or electronics. Seamless aluminum cylinder has a durable epoxy paint finish. Long-lasting nickelchrome plated brass valve with stainless steel handle and lever. Includes a heavy-duty wall hanger. 5 year warranty. Non-Returnable. 5 pounds UL Rating: 5B:C |
 |
5 lb Carbon Dioxide Cylinder (5lb CO2 Tank) This cylinder is able to hold 5 lbs of CO2. It is constructed of light weight aluminum with matte aluminum finish. CO2 Cylinders are shipped empty. You can fill your CO2 cylinder at a local welding shop or fire safety supply. Features: * Brand New * Aluminum * High Quality |
 |
Nellcor Easy Cap II CO2 Detector, Adult by Puritan Bennett For years, hospital and emergency medical services clinicians have relied on Nellcor Easy Cap II and Pedi Cap CO2 Detectors to verify proper endotracheal tube placement. These CO2 detectors assure you that your patient is intubated properly right from the start - and remains that way during transport. The easy-to-use CO2 detector attaches directly to the ET tube and responds quickly to exhaled CO2 with a simple color change from purple to yellow. Easy Cap II and Pedi Cap CO2 Detectors are an economical, yet invaluable airway management tool. Features of Nellcor Easy Cap II CO2 Detector: Reliable carbon dioxide detectors help verify endotracheal tube placement. Responds quickly to exhaled CO2 with a simple color change from purple to yellow. Breath-to-breath response. ... |
 |
Pulmocare Liquid Nutrition for Pulmonary Patients, Vanilla, Case of 24 Cans- each 8 Fluid Ounces (237 ml) by Pulmocare Pulmocare liquid vanilla nutritional supplement - A high calorie, low-carbohydrate liquid formula, designed to help reduce carbon dioxide production, thereby minimizing CO2 retention. Lactose and gluten free. For supplemental or sole-source nutrition. Oral or tube feeding. |
|
Carbon Dioxide Incubator Accessories for Isotemp/Thermo Scientific NAPCO Models; Roller Base by Thermo Scientific Forma Roller Base, Incubator Accessory; For Isotemp DH and NAPCO 8000 Series DH CO2 Incubators; with locking casters and leveling feet |
| © 2009 BrightSurf.com |