Scientist to Gather Greenhouse Gas Emissions from Melting Permafrost

Goddard scientist Emily Wilson poses here with an early version or prototype of her recently miniaturized laser heterodyne radiometer — an instrument for which she received a patent in 2014. Image Credit: NASA

A NASA scientist who has developed a novel suitcase-size instrument to measure column carbon dioxide and methane is taking her recently patented instrument on the road this summer to comprehensively measure emissions of these important greenhouse gases from Alaska’s melting permafrost. 

Emily Wilson, a scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, will use her recently patented miniaturized laser heterodyne radiometer (mini-LHR) to carry out a multi-disciplinary field campaign at three sites — each representing a different type of permafrost — near Fairbanks, Alaska, in June. Her team has designed a unique and comprehensive experiment that records permafrost depth and structure, meteorological data, and concentrations of methane and carbon dioxide during the seasonal ground melt.

Multi-Disciplinary Approach

“With the global mean temperature rising, the release of these gases could create an amplified effect,” she said. “These data will allow us to estimate fluctuation of emissions from the melting permafrost.”

Permafrost is permanently frozen soil. Comprising 24 percent of the Northern Hemisphere, permafrost contains old organic carbon deposits — some relicts from the last glaciation — that are locked up beneath the surface. Scientists have observed that more of the permafrost’s upper layer, or the active layer, is melting each summer, creating concern that the thawing could lead to the significant greenhouse-gas emissions.

Further exacerbating the situation is the fact that while methane doesn’t linger as long as carbon dioxide in the atmosphere, it is more potent and effective at absorbing heat, creating a positive feedback, where emissions leads to more warming, which in turn accelerates the thaw.

Highly portable, the mini-LDR is ideal for permafrost studies, Wilson said. Made up of commercially available components, the instrument literally can go anywhere to measure carbon dioxide and methane in the atmospheric column — that is, the levels of these gases in a vertical column extending from the ground to space. Currently, the only ground-based network that measures these two greenhouse gases in the atmospheric column is the Total Carbon Column Observing Network. However, the network has 22 operational sites globally, with limited coverage in the Arctic.

“We’re targeting areas where there is limited coverage,” she said.

To prepare for the campaign, Wilson made her instrument more rugged and more sensitive. She added a satellite communications port to remotely retrieve data, a thermally controlled instrument housing to protect the instrument from changing temperatures, and a solar grid and battery storage system for powering the instrument in remote locations.

Source: Nasa

Silicon carbide increases energy efficiency

Illustration of the fill port of a silicon single crystal bar which has been prepared by the zone melting process. (Photo: TRUMPF Hüttinger)
To increase the efficiency of the power supply in industrial processes, thereby saving energy and CO2, the aim of the new joint "MMPSiC": Researchers at the Light Technology Institute (LTI) at the Karlsruhe Institute of Technology (KIT) examine together with the industrial partners TRUMPF Hüttinger and IXYS Semiconductor the use of power semiconductor switches of silicon carbide. The Federal Research Ministry is supporting the project with around 800,000 euros.

Of the semiconductor manufacturing over the coating of displays to processes in the automotive industry: Many industrial processes consume large amounts of electrical energy. Among these are technologies that will play an important role in the energy transition, as the zone melting method (float zone method) for producing high purity crystalline materials: The substance is electrically fused in a narrow zone; the melting zone is gradually continued. Behind the melting zone crystallized substance purer than before. The zone melting method provides, among other high-purity silicon single crystals for the manufacture of solar cells.

Power supply of zone melting systems based on tube technology systems are used to now having an electrical efficiency of up to 65 percent. By switching to power semiconductor silicon carbide, the efficiency of the process power supply could be increased to over 80 percent. This would save large amounts of electrical energy and reduce greenhouse gas emissions. For example, for a single float-zone scale plant would result consisting of 20 x 150 kW-process power supplies, with an annual duration of 4800 hours, a savings of more than 200,000 kWh of electrical energy and 109 tonnes of CO2 (Umweltbundesamt, as of July 2013).

The feasibility of such a process power supplies, researchers at the Light Technology Institute (LTI) of KIT together with the partners TRUMPF Hüttinger GmbH + Co. KG (Freiburg) and IXYS Semiconductor GmbH (Lampertheim) in the joint project "Modular medium frequency process power supply with silicon carbide semiconductor power switches" (MMPSiC) , As the semiconductor material Silicon Carbide offers several advantages: Thanks to the larger electronic band gap allows much higher operating temperatures than conventional semiconductors. Power electronics with silicon carbide is characterized by higher energy efficiency and compactness.

"When the power of energy-intensive industrial applications such as the zone melting method, it is necessary to switch at high frequencies," says the project director, Dr. Rainer Kling from LTI of KIT. "Silicon carbide is not yet tested for these high frequencies; so that we are breaking new ground. "In addition to examining the long-term stability include the control and the layout of the circuit to the tasks of the KIT researchers in the joint project MMPSiC.

The Federal Ministry of Education and Research (BMBF) supports MMPSiC project on the basis of the program "Information and Communication Technology 2020" (ICT 2020) as part of the funding program "Power electronics to increase energy efficiency" (LES 2) with around 800,000 euros. Of which receives the LTI KIT around 439,000 euros. Overall, the project volume is 1.3 million euros. The joint project started in 2014 and is planned for three years.

Source: KIT

Mother's diet affects the 'silencing' of her child's genes

An infant from the Gambia. Credit: Felicia Webb

A mother's diet before conception can permanently affect how her child's genes function, according to a study published in Nature Communications.

The first such evidence of the effect in humans opens up the possibility that a mother's diet before pregnancy could permanently affect many aspects of her children's lifelong health.

Researchers from the MRC International Nutrition Group, based at the London School of Hygiene & Tropical Medicine and MRC Unit, The Gambia, utilized a unique 'experiment of nature' in rural Gambia, where the population's dependence on own grown foods and a markedly seasonal climate impose a large difference in people's dietary patterns between rainy and dry seasons.

Through a selection process involving over 2,000 women, the researchers enrolled pregnant women who conceived at the peak of the rainy season (84 women) and the peak of the dry season (83 women). By measuring the concentrations of nutrients in their blood, and later analysing blood and hair follicle samples from their 2-8 month old infants, they found that a mother's diet before conception had a significant effect on the properties of her child's DNA.

While a child's genes are inherited directly from their parents, how these genes are expressed is controlled through 'epigenetic' modifications to the DNA. One such modification involves tagging gene regions with chemical compounds called methyl groups and results in silencing the genes. The addition of these compounds requires key nutrients including folate, vitamins B2, B6 and B12, choline and methionine.

Experiments in animals have already shown that environmental influences before conception can lead to epigenetic changes that affect the offspring. A 2003 study found that a female mouse's diet can change her offspring's coat colour by permanently modifying DNA methylation.1 But until this latest research, funded by the Wellcome Trust and the MRC, it was unknown whether such effects also occur in humans.

Senior author Dr Branwen Hennig, Senior Investigator Scientist at the MRC Gambia Unit and the London School of Hygiene & Tropical Medicine, said: "Our results represent the first demonstration in humans that a mother's nutritional well-being at the time of conception can change how her child's genes will be interpreted, with a life-long impact."

The researchers found that infants from rainy season conceptions had consistently higher rates of methyl groups present in all six genes they studied, and that these were linked to various nutrient levels in the mother's blood. Strong associations were found with two compounds in particular (homocysteine and cysteine), and the mothers' body mass index (BMI) had an additional influence. However, although these epigenetic effects were observed, their functional consequences remain unknown.

Professor Andrew Prentice, Professor of International Nutrition at the London School of Hygiene & Tropical Medicine, and head of the Nutrition Theme at the MRC Unit, The Gambia, said: "Our on-going research is yielding strong indications that the methylation machinery can be disrupted by nutrient deficiencies and that this can lead to disease. Our ultimate goal is to define an optimal diet for mothers-to-be that would prevent defects in the methylation process. Pre-conceptional folic acid is already used to prevent defects in embryos. Now our research is pointing towards the need for a cocktail of nutrients, which could come from the diet or from supplements."

Dr Rob Waterland of Baylor College of Medicine in Houston, who conducted the epigenetic analyses said: "We selected these gene regions because our earlier studies in mice had shown that establishment of DNA methylation at metastable epialleles is particularly sensitive to maternal nutrition in early pregnancy."

The authors note that their study was limited by including only one blood sampling point during early pregnancy, but estimates of pre-conception nutrient concentrations were calculated using results from non-pregnant women sampled throughout a whole calendar year. The authors also plan to increase the sample size in further studies.

Source: London School of Hygiene & Tropical Medicine

Soil mineral surfaces linked to key atmospheric processes

Pictured are, from left, are David Bish, Melissa Donaldson and Jonathan Raff. Credit: Indiana University

Research by Indiana University scientists finds that soil may be a significant and underappreciated source of nitrous acid, a chemical that plays a pivotal role in atmospheric processes such as the formation of smog and determining the lifetime of greenhouse gases.

The study shows for the first time that the surface acidity of common minerals found in soil determines whether the gas nitrous acid will be released into the atmosphere. The finding could contribute to improved models for understanding and controlling air pollution, a significant public health concern.

"We find that the surfaces of minerals in the soil can be much more acidic than the overall pH of the soil would suggest," said Jonathan Raff, assistant professor in the School of Public and Environmental Affairs and Department of Chemistry. "It's the acidity of the soil minerals that acts as a knob or a control lever, and that determines whether nitrous acid outgasses from soil or remains as nitrite."

The article, "Soil surface acidity plays a determining role in the atmospheric-terrestrial exchange of nitrous acid," will be published this week in the journal Proceedings of the National Academy of Sciences. Melissa A. Donaldson, a Ph.D. student in the School of Public and Environmental Affairs, is the lead author. Co-authors are Raff and David L. Bish, the Haydn Murray Chair of Applied Clay Mineralogy in the Department of Geological Sciences.

Nitrous acid, or HONO, plays a key role in regulating atmospheric processes. Sunlight causes it to break down into nitric oxide and the hydroxyl radical, OH. The latter controls the atmospheric lifetime of gases important to air quality and climate change and initiates the chemistry leading to the formation of ground-level ozone, a primary component of smog.
Scientists have known about the nitrous acid's role in air pollution for 40 years, but they haven't fully understood how it is produced and destroyed or how it interacts with other substances, because HONO is unstable and difficult to measure.

"Only in the last 10 years have we had the technology to study nitrous acid under environmentally relevant conditions," Raff said.

Recent studies have shown nitrous acid to be emitted from soil in many locations. But this was unexpected because, according to basic chemistry, the reactions that release nitrous acid should take place only in extremely acidic soils, typically found in rain forests or the taiga of North America and Eurasia.

The standard method to determine the acidity of soil is to mix bulk soil with water and measure the overall pH. But the IU researchers show that the crucial factor is not overall pH but the acidity at the surface of soil minerals, especially iron oxides and aluminum oxides. At the molecular level, the water adsorbed directly to these minerals is unusually acidic and facilitates the conversion of nitrite in the soil to nitrous acid, which then volatilizes.

"With the traditional approach of calculating soil pH, we were severely underestimating nitrous acid emissions from soil," Raff said. "I think the source is going to turn out to be more important than was previously imagined."

The research was carried out using soil from a farm field near Columbus, Ind. But aluminum and iron oxides are ubiquitous in soil, and the researchers say the results suggest that about 70 percent of Earth's soils could be sources of nitrous acid.

Ultimately, the research will contribute to a better understanding of how nitrous acid is produced and how it affects atmospheric processes. That in turn will improve the computer models used by the U.S. Environmental Protection Agency and other regulatory agencies to control air pollution, which the World Health Organization estimates contributes to 7 million premature deaths annually.

"With improved models, policymakers can make better judgments about the costs and benefits of regulations," Raff said. "If we don't get the chemistry right, we're not going to get the right answers to our policy questions regarding air pollution."

Source: Indiana University

Kudzu can release soil carbon, accelerate global warming

This layer of decomposing knotweed will eventually form soil organic matter in invaded ecosystems.
 Credit: Image courtesy of Clemson University

Clemson University scientists are shedding new light on how invasion by exotic plant species affects the ability of soil to store greenhouse gases. The research could have far-reaching implications for how we manage agricultural land and native ecosystems.

In a paper published in the scientific journal New Phytologist, plant ecologist Nishanth Tharayil and graduate student Mioko Tamura show that invasive plants can accelerate the greenhouse effect by releasing carbon stored in soil into the atmosphere.
Since soil stores more carbon than both the atmosphere and terrestrial vegetation combined, the repercussions for how we manage agricultural land and ecosystems to facilitate the storage of carbon could be dramatic.

In their study, Tamura and Tharayil examined the impact of encroachment of Japanese knotweed and kudzu, two of North America's most widespread invasive plants, on the soil carbon storage in native ecosystems.

They found that kudzu invasion released carbon that was stored in native soils, while the carbon amassed in soils invaded by knotweed is more prone to oxidation and is subsequently lost to the atmosphere.

The key seems to be how plant litter chemistry regulates the soil biological activity that facilitates the buildup, composition and stability of carbon-trapping organic matter in soil.

"Our findings highlight the capacity of invasive plants to effect climate change by destabilizing the carbon pool in soil and shows that invasive plants can have profound influence on our understanding to manage land in a way that mitigates carbon emissions," Tharayil said.

Tharayil estimates that kudzu invasion results in the release of 4.8 metric tons of carbon annually, equal to the amount of carbon stored in 11.8 million acres of U.S. forest.
This is the same amount of carbon emitted annually by consuming 540 million gallons of gasoline or burning 5.1 billion pounds of coal.

"Climate change is causing massive range expansion of many exotic and invasive plant species. As the climate warms, kudzu will continue to invade northern ecosystems, and its impact on carbon emissions will grow," Tharayil said.

The findings provide particular insight into agricultural land-management strategies and suggest that it is the chemistry of plant biomass added to soil rather than the total amount of biomass that has the greatest influence on the ability of soil to harbor stable carbon.

"Our study indicates that incorporating legumes such as beans, peas, soybeans, peanuts and lentils that have a higher proportion of nitrogen in its biomass can accelerate the storage of carbon in soils," Tharayil said.

Thrarayil's lab is following up this research to gain a deeper understanding of soil carbon storage and invasion.

Tharayil leads a laboratory and research team at Clemson that studies how the chemical and biological interactions that take place in the plant-soil interface shape plant communities. He is also the director of Clemson's Multi-User Analytical Laboratory, which provides researchers with access to highly specialized laboratory instruments.

Source: Clemson University

Permafrost soil: Possible source of abrupt rise in greenhouse gases at end of last ice age

Pleistocene Ice Complex cliff: 35 meters high Pleistocene Ice Complex cliff at Sobo Sise Island (Lena Delta), Siberian Arctic. Credit: Alfred-Wegener-Institut / Thomas Opel

Scientists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have identified a possible source of carbon dioxide (CO2) and other greenhouse gases that were abruptly released to the atmosphere in large quantities around 14,600 years ago. According to this new interpretation, the CO2 -- released during the onset of the Bølling/Allerød warm period -- presumably had their origin in thawing Arctic permafrost soil and amplified the initial warming through positive feedback. The study now appears online in the journal Nature Communications.

One of the most abrupt rises in the carbon dioxide concentration in the atmosphere at the end of the last ice age took place about 14,600 years ago. Ice core data show that the CO2 concentration at that time increased by more than 10 ppm (parts per million, unit of measure for the composition of gases) within 200 years. This CO2 increase, i.e. approx. 0.05 ppm per year, was significantly less than the current rise in atmospheric CO2 of 2-3 ppm in the last decade caused by fossil fuels. These data describe an abrupt change in the global carbon cycle during the transition from the last ice age to the present-day warm interglacial and allow conclusions to be drawn about similar processes that could play a role in the future.

To determine the origin of the greenhouse gas, a team around by the geoscientists and climate researchers Dr. Peter Köhler and Dr. Gregor Knorr from the Alfred Wegener Institute has carried out computer simulations focusing on the new interpretation of these CO2 data. These calculations were motivated by new radiocarbon data (14C) that provide information on the age of the CO2 released to the atmosphere. The age of the carbon then allows conclusions to be drawn about the carbon source.

"The virtual lack of radiocarbon in the CO2 that was released into the atmosphere shows us that the carbon must have been very old," says Köhler. The carbon therefore cannot be originated from the deep ocean, Köhler adds: "The carbon stored in the deep ocean has been subject to exchange with the atmosphere over a period of millennia. In the atmosphere 14C has its only source. It is produced through the impact of galactic cosmic rays on molecules in the atmosphere." However, radiocarbon is unstable and decays with a half-life of around 5,700 years. The atmospheric data of CO2 and 14C can only be explained if a carbon source is assumed that contains virtually no 14C any more -- thus the greenhouse gases must have had another source than the deep ocean.

Permafrost soil contains, to some extent, very old organic material, which is released in the form of the greenhouse gases CO2 and methane when the soil thaws. Permafrost soil thus might be a possible source of old carbon. The thawing of Arctic permafrost soil might have been caused by a sudden resumption of large-scale Atlantic heat transport in the ocean that initiated the Bølling/Allerød warm period in the high northern hemisphere.

The scientists were able to estimate the amount of the carbon dioxide released to the atmosphere by applying a computer model that simulates the global carbon cycle. The simulation results indicate that the input of more than half a gigaton of carbon per year (1 gigaton = 1 petagram) over a period of two centuries is necessary to explain the observed data. This corresponds to a total amount of more than 100 gigatons of carbon. Present-day anthropogenic CO2 emissions due to fossil fuels, at approx. ten gigatons of carbon a year, are greater than the release rates of this natural process by a factor of at least ten.

According to the study, the proposed thawing of large areas of permafrost, followed by the rise in greenhouse gases, occurred at the same time as the warming in the northern hemisphere at the beginning of the Bølling warm period. The released greenhouse gases may amplify the initial warming through feedback effects.

A similar effect is also predicted for the future in the current IPCC report. Warming in Siberia, for instance, is already leading to thawing of permafrost soil: outgassing of CO2 and methane takes place. The same processes observed today -- and are expected to an even greater extent in the coming decades -- presumably occurred in a similar manner 14,600 years ago. "However, the state of the climate on Earth today has already been changed by anthropogenically emitted greenhouse gases. Future CO2 release due to the proposed thawing of permafrost will be substantially less than the input due to fossil fuels. However, these emissions from permafrost soil are additional greenhouse gas sources that further amplify the anthropogenically induced effect," says Köhler.

Source:  Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research

Solar activity impacts polar ozone

Scientists have been able to confirm, for the first time, the long-term implications of solar-driven electron impact on the upper middle atmosphere ozone. Credit: NASA

The increase in greenhouse gases explains, to a large extent, the rise in the average temperature of Earth. According to the research study published in Nature Communications today, the Sun affects middle atmosphere ozone with potential implications on smaller scale to regional, but not global, climate.

Humankind is responsible for the global warming of our climate by increasing the amount of greenhouse gases in the atmosphere. However, according results published today, fluctuations in the activity of the Sun impact middle atmosphere ozone, providing a potential link to regional scale climate variability. This climate variability is not a trend, like climate change, but rather year-to-year fluctuations following solar activity. "The detected ozone variation may in part help understand the alternation of local mild and cold winter seasons, as hints have been obtained in previous research that the ozone changes in the middle atmosphere may link as far as the surface of Earth and affect, among other things, polar wind streams," Finnish Meteorological Institute researcher Dr Pekka Verronen reflects.

The research team was able to confirm, for the first time, the long-term implications of solar-driven electron impact on the upper middle atmosphere ozone. The results showed strong effects in the polar latitudes. The amount of ozone at 70-80 km altitude was found to vary more than 30 percent during a solar cycle, a period of approximately 11 years. The ozone variation between the extremes of the Sun's activity is so great that it is likely to impact the temperature balance of the atmosphere. These temperature changes can in turn have an effect on atmospheric winds.

Electrons from space: Auroras and ozone loss

According to the research study conducted by the Finnish Meteorological Institute, University of Otago and the British Antarctic Survey, the electrons, similar to those behind the aurora, cause significant solar cycle variation in the polar mesosphere ozone. The amount of ozone is smaller when more electrons enter the atmosphere. "These results are only the first step but an important one, allowing us to better understand the long-term impacts of this type of solar activity, and its role in regional climate variability," says Dr Monika Andersson who lead the study at Finnish Meteorological Institute.

Earth's radiation belts are regions in near-Earth space that contain vast quantities of solar energetic electrons, trapped there by Earth's magnetic field. During magnetic storms, which are solar wind-driven, the electrons accelerate to high speeds and enter the atmosphere in the polar regions. In the atmosphere, the electrons ionize gas molecules, leading to the production of ozone-depleting catalyst gases. Based on currently available satellite observations, electron precipitation may, during solar storms lasting a few days, reduce ozone in the upper atmosphere (60-80 km) as much as 90 per cent on a momentary basis.

Source: Finnish Meteorological Institute

No laughing matter: Nitrous oxide rose at end of last ice age

Researchers measured increases in atmospheric nitrous oxide concentrations about 16,000 to 10,000 years ago using ice from Taylor Glacier in Antarctica. Credit: Adrian Schilt

Nitrous oxide (N₂O) is an important greenhouse gas that doesn't receive as much notoriety as carbon dioxide or methane, but a new study confirms that atmospheric levels of (N₂O) rose significantly as the Earth came out of the last ice age and addresses the cause.

An international team of scientists analyzed air extracted from bubbles enclosed in ancient polar ice from Taylor Glacier in Antarctica, allowing for the reconstruction of the past atmospheric composition. The analysis documented a 30 percent increase in atmospheric nitrous oxide concentrations from 16,000 years ago to 10,000 years ago. This rise in N2O was caused by changes in environmental conditions in the ocean and on land, scientists say, and contributed to the warming at the end of the ice age and the melting of large ice sheets that then existed.

The findings add an important new element to studies of how Earth may respond to a warming climate in the future. Results of the study, which was funded by the U.S. National Science Foundation and the Swiss National Science Foundation, are being published this week in the journal Nature.

"We found that marine and terrestrial sources contributed about equally to the overall increase of nitrous oxide concentrations and generally evolved in parallel at the end of the last ice age," said lead author Adrian Schilt, who did much of the work as a post-doctoral researcher at Oregon State University. Schilt then continued to work on the study at the Oeschger Centre for Climate Change Research at the University of Bern in Switzerland.

"The end of the last ice age represents a partial analog to modern warming and allows us to study the response of natural nitrous oxide emissions to changing environmental conditions," Schilt added. "This will allow us to better understand what might happen in the future."

Nitrous oxide is perhaps best known as laughing gas, but it is also produced by microbes on land and in the ocean in processes that occur naturally, but can be enhanced by human activity. Marine nitrous oxide production is linked closely to low oxygen conditions in the upper ocean and global warming is predicted to intensify the low-oxygen zones in many of the world's ocean basins. N2O also destroys ozone in the stratosphere.

"Warming makes terrestrial microbes produce more nitrous oxide," noted co-author Edward Brook, an Oregon State paleoclimatologist whose research team included Schilt. "Greenhouse gases go up and down over time, and we'd like to know more about why that happens and how it affects climate."

Nitrous oxide is among the most difficult greenhouse gases to study in attempting to reconstruct Earth's climate history through ice core analysis. The specific technique that the Oregon State research team used requires large samples of pristine ice that date back to the desired time of study -- in this case, between about 16,000 and 10,000 years ago.

The unusual way in which Taylor Glacier is configured allowed the scientists to extract ice samples from the surface of the glacier instead of drilling deep in the polar ice cap because older ice is transported upward near the glacier margins, said Brook, a professor in Oregon State's College of Earth, Ocean, and Atmospheric Sciences.

The scientists were able to discern the contributions of marine and terrestrial nitrous oxide through analysis of isotopic ratios, which fingerprint the different sources of N2O in the atmosphere.

"The scientific community knew roughly what the N2O concentration trends were prior to this study," Brook said, "but these findings confirm that and provide more exact details about changes in sources. As nitrous oxide in the atmosphere continues to increase -- along with carbon dioxide and methane -- we now will be able to more accurately assess where those contributions are coming from and the rate of the increase."

Atmospheric N2O was roughly 200 parts per billion at the peak of the ice age about 20,000 years ago then rose to 260 ppb by 10,000 years ago. As of 2014, atmospheric N2Owas measured at about 327 ppb, an increase attributed primarily to agricultural influences.
Although the N2O increase at the end of the last ice age was almost equally attributable to marine and terrestrial sources, the scientists say, there were some differences.

"Our data showed that terrestrial emissions changed faster than marine emissions, which was highlighted by a fast increase of emissions on land that preceded the increase in marine emissions," Schilt pointed out. "It appears to be a direct response to a rapid temperature change between 15,000 and 14,000 years ago."

That finding underscores the complexity of analyzing how Earth responds to changing conditions that have to account for marine and terrestrial influences; natural variability; the influence of different greenhouse gases; and a host of other factors, Brook said.

"Natural sources of N2O are predicted to increase in the future and this study will help up test predictions on how the Earth will respond," Brook said.

Source: Oregon State University