Lehman

Kirk Bryan Award goes to a team of INSTAARs, colleagues

Anonymous — Thu, 19 Oct 2023 21:34:00 +0000

Kirk Bryan Award goes to a team of INSTAARs, colleagues Anonymous (not verified) Thu, 10/19/2023 - 15:34

Shelly Sommer

A team of researchers that included several INSTAAR scientists received the prestigious Kirk Bryan Award from the Quaternary Geology & Geomorphology Division of the Geological Society of America (GSA). The prestigious award honors the authors of a recent paper that advances the science of geomorphology.

Led by former INSTAAR PhD student Simon Pendleton, now an Assistant Professor of Practice at Plymouth State University, the team of researchers included INSTAARs Gifford Miller, Scott Lehman, Sarah Crump, and Robert S. Anderson and colleagues Nathaniel Lifton from Purdue University and John Southon from the University of California, Irvine.

Their paper in Nature Communications, “Rapidly receding Arctic Canada glaciers revealing landscapes continuously ice-covered for more than 40,000 years,” was published in 2019. The study looked at the ages of ancient plants preserved by now-receding ice caps in Arctic Canada. It found that the summer warmth of the past century now exceeds any century in within the past 115,000 years. In an acceptance speech at the GSA annual meeting, Pendleton described a long and collaborative process that led to the paper’s publication, involving, “the chance collection of preserved plants nearly 60 years ago, some not insignificant improvements in radiocarbon dating, the invention of an entirely new surface dating technique (cosmogenic exposure dating), and the perseverance of individuals in the pursuit of understanding these landscapes and the climate secrets they hold.” The researchers spent hours walking ice margins on Baffin Island and processed hundreds of preserved plants in labs to date the plants and place them in a context stretching for thousands of years. He added, “In many ways, this paper encapsulates the theme of the Kirk Bryan award: the innovations made by others over past decades enabled our team to continue to advance the field and our understanding of these glacier-climate systems.”

“It was only recently that I fully appreciated the irony of this particular project,” said Pendleton. “The irony that the warming of the climate—the very thing we are attempting to quantify and characterize—is revealing to us, through ice recession, the data we need to do it. These newly exposed materials are ephemeral, and once they are gone, the record is lost forever.”

The award comes with a monetary prize, which the authors will donate to the Sarah Crump Graduate Fellowship. Sarah Crump was an author on the paper who contributed significantly to the field and lab portions of the study. She passed away in 2022 after a battle with cancer, leaving a legacy of outstanding paleoclimate science paired with a strong commitment to inclusion and community building.

Previous Kirk Bryan Award winners from the University of ŷ��ڱ��Ƶ Boulder include John Andrews in 1973 and Peter Birkeland in 1988.

Simon Pendleton and Giff Miller collect ancient plant remains melted out of the edge of an ice cap on Baffin Island. Photo by Matt Kennedy, Earth Vision Trust.

Giff Miller holds a clump of ancient moss, recently melted out of the edge of an ice cap on Baffin Island. Photo by Matthew Kennedy, Earth Vision Trust.

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Lawns and landscaping complicate taking the measure of Los Angeles Basin’s carbon footprint

Anonymous — Mon, 12 Oct 2020 06:00:00 +0000

Lawns and landscaping complicate taking the measure of Los Angeles Basin’s carbon footprint Anonymous (not verified) Mon, 10/12/2020 - 00:00

Adapted from a NOAA news story

The Los Angeles Basin is often thought of as a dry, heavily developed landscape. But a new study led by NOAA and the University of ŷ��ڱ��Ƶ Boulder shows that the manicured lawns, emerald golf courses, and trees of America’s second-largest city play a surprisingly large role in its carbon emissions.

Megacities like Los Angeles contribute significantly to national and global carbon dioxide emissions and are an increasingly important priority for mitigation efforts, the scientists said. What this study showed, however, was that measuring emissions accurately isn’t as simple as, for example, taking a snapshot of carbon dioxide levels from remote sensing data. Plants in urban environments can complicate the picture.

Working as part of the Megacities Carbon Project, the scientists analyzed the carbon dioxide, or CO₂, in around 500 air samples collected during 2015 from four sites around the basin for the presence of a rare radioactive isotope known as carbon-14. Because it is radioactive, carbon-14 slowly decays away over time. Carbon-14 is found in living organisms, including vegetation. But fossil fuels, which are millions of years old, are totally devoid of carbon-14. Thus, the isotope can be used to differentiate carbon dioxide emitted during combustion of fossil fuels from that released by plants.

Lead author John Miller, a carbon cycle scientist with NOAA’s Global Monitoring Laboratory, said that when researchers disentangled the carbon dioxide generated by burning fossil fuels from that generated by vegetation, they found that L.A.’s green landscape contributed substantially to the changes in carbon dioxide levels around the city.

“L.A. is a very dry place,” Miller said. “You think of L.A., you think of freeways and sprawl. The natural environment outside the city is not naturally lush. In addition, 2015 was a big drought year, so it was all the more surprising that so much of the CO₂ in our measurements came from living plants.”

The timing of the increased carbon dioxide drawdown from the growth of plants was another surprise. In a normal Mediterranean climate, winter rains are followed by a dry season. Plants respond by drawing in carbon dioxide in early spring when rain is available, and emitting it in late summer and fall as they go dormant during the dry season.

“L.A. has a Mediterranean climate but we saw CO₂ levels drawn down in the middle of summer, in response to the watering of lawns, golf courses, trees—even though 2015 was a drought year with water restrictions,” he said. “Irrigation was compensating for the lack of rain, and keeping the urban ecosystem active.”

This seasonal fluctuation in ecosystem carbon dioxide amounted to one third of the CO₂ level resulting from combustion of fossil fuels.

Riley Duren, a research scientist at the University of Arizona who began this research while at NASA’s Jet Propulsion Laboratory, said that this study is part of a broader program to support science-based decision making at local scales and to develop actionable carbon measurement methods that can be extended to cities globally. “It also helps lay the foundation for using carbon-14 measurements as a reference point to improve and correct other tracers of fossil-fuel carbon dioxide emissions.”

The team is working with colleagues from other pilot projects around the world with a goal of ultimately establishing a sustained, global carbon monitoring system for cities.

The carbon-14 approach, which Miller and INSTAAR scientist Scott Lehman have been developing since 2003, allows them to separately track carbon dioxide from ecosystems and from fossil fuel use. A recent study applied this method to determine US emissions at the national scale, and here it was used to better understand the different sources contributing to the overall urban carbon emissions.

The takeaway, Miller and Lehman said, is that understanding the urban carbon footprint—how much carbon is produced in a city—is a lot more complicated than simply cataloging fossil fuel use and emissions. It highlights the need to more accurately measure and track fossil-fuel emissions, as well as the impact of urban vegetation and greening campaigns to develop and evaluate emissions mitigation strategies.

“If you are the mayor of a major city and you’re interested in your city’s total carbon balance, you should be interested in how active your biosphere is as well,” Miller said. “You can’t just look at CO₂ concentrations alone. You can imagine that if the biospheric signal is as large as it is for a dry city like L.A., in wetter places like Mumbai and S̴ão Paulo, ecosystem-produced CO₂ could be an even larger part of the carbon budget.”

Lehman concludes, “It’s important to note that the net CO₂ signal from the urban biosphere may change from year to year and from place to place, depending on factors such as sunlight, temperature and rainfall and—as our results from LA underscore—urban irrigation. On the other hand, CO₂ emissions from fossil fuel use are always net positive and must be reduced drastically if we hope to avoid consequences of manmade warming beyond those that are already baked in. Our results demonstrate the need to track CO₂ variations from both the urban biosphere and fossil fuel use—and how one might actually do so.”

Funding for this research was provided by NOAA and NASA’s Jet Propulsion Laboratory. The L.A. Megacity Carbon Project is supported by NASA, the National Institute of Standards and the California Air Resources Board.

The Los Angeles Basin is often thought of as a dry, heavily developed landscape. But a new study in PNAS led by NOAA and the University of ŷ��ڱ��Ƶ Boulder shows that the manicured lawns, emerald golf courses, and trees of America’s second-largest city play a surprisingly large role in its carbon footprint.

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Radioactive bookkeeping of carbon emissions (Eos)

Anonymous — Wed, 24 Jun 2020 06:00:00 +0000

Radioactive bookkeeping of carbon emissions (Eos) Anonymous (not verified) Wed, 06/24/2020 - 00:00

Sarah Derouin

A new sampling method uses carbon-14 to single out which carbon dioxide molecules in the atmosphere derive from fossil fuels. The method could help track emissions goals for climate mitigation.

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Tracking fossil fuel emissions with carbon-14

Anonymous — Mon, 01 Jun 2020 22:21:28 +0000

Tracking fossil fuel emissions with carbon-14 Anonymous (not verified) Mon, 06/01/2020 - 16:21

Modified from a NOAA story by Theo Stein.

In a paper published in the Proceedings of the National Academy of Sciences, they report the first-ever national scale estimate of fossil-fuel derived carbon dioxide (CO₂) emissions obtained by observing CO₂ and its naturally occurring radioisotope, carbon-14, from air samples collected by the NOAA Global Greenhouse Gas Reference Network.

Carbon-14 allows us to pull back the veil and isolate CO₂ emitted from fossil fuel combustion - Scott Lehman

Carbon-14, a rare isotope of carbon created largely by cosmic rays, has a half-life of 5,700 years. The carbon in fossil fuels has been buried for millions of years and therefore is completely devoid of carbon-14. Careful laboratory analysis can quantify the reduction of carbon-14 in individual air samples, which in turn reflects the amount of CO₂ coming from fossil fuel combustion and cement manufacturing (which also produces no carbon-14). Knowing the location, date and time when the air samples were taken, the research team used a model of atmospheric transport to isolate the fossil CO₂ signal and trace it back to sources at the surface.

“This is a new, independent, and objective method for evaluating emission inventories that is based on what we actually observe in the atmosphere,” said lead author Sourish Basu, who was a CIRES scientist working at NOAA during the study. He is now a scientist at NASA’s Goddard Space Flight Center in Maryland.

While the link between fossil CO₂ emissions and atmospheric carbon-14 has been known for many decades, the construction of a national-scale emission estimate based on atmospheric carbon-14 required the simultaneous development of precise measurement techniques and an emissions estimation framework, largely spearheaded over the past 15 years by NOAA scientist John Miller and INSTAAR scientist Scott Lehman.

“Carbon-14 allows us to pull back the veil and isolate CO₂ emitted from fossil fuel combustion,” said Lehman, one of the paper’s authors. “It provides us with a clear fossil CO₂ signal we can track to sources on the ground. We can then add these up and compare to other emissions estimates at various time and space scales.

The study team used measurements of atmospheric carbon dioxide and its carbon-14 content to “unmask” the contribution of carbon dioxide from fossil fuel combustion and cement production. Because fossil fuels and materials used to produce cement are devoid of carbon-14, their emissions appear as areas of low carbon-14 (shown in warm colors) that can be traced back to sources at the surface using atmospheric transport models. Figure courtesy of Sourish Basu.

Accurately calculating emissions of carbon dioxide from burning fossil fuels has challenged scientists for years. The two primary methods in current use—“bottom up” inventories and “top down” atmospheric studies used in regional campaigns—each have their strengths and weaknesses.

"Bottom-up" estimates, such as those used in the Environmental Protection Agency (EPA) Inventory of U.S. Greenhouse Gas Emissions and Sinks, are developed by counting CO₂ emissions from various processes and fuel types, and then scaling up emissions based on records of fossil fuel use. In contrast, "top-down" estimates are based on measured changes in the concentrations of emitted gases in the atmosphere and wind patterns connecting the surface source regions with the measurement locations.

Bottom-up inventories can provide more information on emissions from individual economic sectors than top-down methods, but their accuracy depends on the ability to track all emission processes and their intensities at all times, which is an intrinsically difficult task with uncertainties that are hard to quantify. Top-down studies are limited by the density of atmospheric measurements and the ability to accurately represent atmospheric circulation patterns but implicitly account for all possible sectors of the economy that emit CO₂.

The team constructed annual and monthly top-down fossil CO₂ emission estimates for the U.S. for 2010, the first year with sufficient atmospheric samples to provide robust results. As one key point of comparison, they compared their numbers to bottom-up estimates from a recent EPA report of 2010 emissions. The team’s estimate of the U.S. annual total 2010 emission was 5 percent higher than EPA’s central estimate and beyond EPA’s upper 95th percentile confidence limit. The new estimate is also significantly higher than those from other inventories commonly used in global and regional CO₂ research, even after adjustment to account for emissions that would be captured by the atmospheric observing network but which are often excluded from inventories, such as in-country emissions from international aviation. On the other hand, the atmospheric results appear to agree with a recent update of the Vulcan U.S. emissions data product developed by researchers at Northern Arizona University. See a news release from Northern Arizona University on the agreement between the two approaches, which use completely different data sources, on the AAAS EurekAlert website.

These figures summarize key findings of the study, showing that the new carbon-14 based estimates of U.S. carbon dioxide emissions are higher than most other estimates. The figure on the left shows annual U.S. emissions for 2010 as reported in this study and from the updated Vulcan emissions data product, the EPA, and three other emission inventories. The error bars are 95% confidence intervals. The figure on the right shows monthly U.S. emissions in 2010 as reported in the study in red (along with associated 68% and 95% confidence intervals). The new results closely match monthly values from the latest release of the Vulcan emission data product, shown as purple dots. Figure courtesy Sourish Basu.

As these were the first estimates constructed using the new observing system, the scientists cautioned that they should be considered provisional. Now they are busy applying the method to measurements from subsequent years to determine if the differences they see are robust over time.

“Independent verification of annual and regional totals and multi-year trends using independent methods like this would promote confidence in the accuracy of emissions reporting, and could help guide future emissions mitigation strategies,” said Miller.

Lehman added, “It was nice to see 2010 totals in the same ball park as some other estimates, but if the difference between our estimate and that from the US EPA of about 5 percent holds up, it is not trivial given EPA’s determination that US emissions have declined only about 10 percent in the decade since. Emissions decreases closer to 40 or 50 percent per decade are what will be needed to fend off the worst consequences of human-caused global warming. We should be in a strong position to monitor progress either way.”

The EPA is tasked with reporting U.S. emissions of CO₂ and other greenhouse gases to the United Nations Framework Convention on Climate Change. That obligation stands whether or not the US remains a party to the 2015 Paris Climate Accord.

The study was supported by NOAA, NASA, and the Department of Energy. Other members of the research team included scientists from Northern Arizona University and the University of California at Irvine.

To read the NOAA version of this news release, including implications of this study for regional carbon inventories, visit the NOAA Research website.

Researchers from NOAA and the University of ŷ��ڱ��Ƶ have devised a breakthrough method for estimating national emissions of carbon dioxide from fossil fuels using ambient air samples and a well-known isotope of carbon scientists have relied on for decades to date archaeological sites. In a paper published in Proceedings of the National Academy of Sciences, they report the first-ever national scale estimate of fossil-fuel derived carbon dioxide (CO2) emissions obtained by observing CO2 and its naturally occurring radioisotope, carbon-14, from air samples collected by NOAA’s Global Greenhouse Gas Reference Network.

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Image: INSTAAR researcher Chad Wolak prepares NOAA air samples for carbon-14 measurement. Photo by Scott Lehman.