Jocelyn Christine Turnbull

GNS Science · National Isotope Centre

Accurate, high‐resolution and sector‐specific greenhouse gas emissions information is increasingly needed for the development of local, targeted mitigation policies. We describe a detailed, spatially and temporally resolved CO2 emissions data product, Mahuika‐Auckland, for Auckland, New Zealand, based on Auckland's regional greenhouse gas and air e...

On rocky tectonic coasts, data from Holocene marine terraces may constrain the timing of coseismic uplift and help identify the causative faults. Challenges in marine terrace investigations include: 1) identifying the uplift datums; 2) obtaining ages that tightly constrain the timing of uplift; 3) distinguishing tsunami deposits from beach deposits...

We present the comparison of source-partitioned CO2 flux measurements with a high-resolution urban CO2 emissions inventory (Hestia). Tower-based measurements of CO and ¹⁴C are used to partition net CO2 flux measurements into fossil and biogenic components. A flux footprint model is used to quantify spatial variation in flux measurements. We compare...

COVID-19 lockdowns resulted in dramatic changes to fossil fuel CO2 emissions around the world, most prominently in the transportation sector. Yet travel restrictions also hampered observational data collection, making it difficult to evaluate emission changes as they occurred. To overcome this, we used a novel citizen science campaign to detect emi...

Urban regions emit a large fraction of anthropogenic emissions of greenhouse gases (GHG) such as carbon dioxide (CO2) and methane (CH4) that contribute to modern-day climate change. As such, a growing number of urban policymakers and stakeholders are adopting emission reduction targets and implementing policies to reach those targets. Over the past...

We tested the capabilities of urban greenhouse gas (GHG) measurement networks to detect abrupt changes in emissions, such as those caused by the roughly 6-week COVID-19 lockdown in March 2020 using hourly in situ GHG mole fraction measurements from six North American cities. We compared observed changes in CO 2 , CO, and CH 4 for different mole fra...

The rapidly expanding and energy-intensive production from the Canadian oil sands, one of the largest oil reserves globally, accounts for almost 12 % of Canada's greenhouse gas emissions according to inventories. Developing approaches for evaluating reported methane (CH4) emission is crucial for developing effective mitigation policies, but only on...

This paper presents a compilation of atmospheric radiocarbon for the period 1950–2019, derived from atmospheric CO 2 sampling and tree rings from clean-air sites. Following the approach taken by Hua et al. (2013), our revised and extended compilation consists of zonal, hemispheric and global radiocarbon ( ¹⁴ C) data sets, with monthly data sets for...

Direct atmospheric ¹⁴ CO 2 measurements began in New Zealand in 1954, initially to improve ¹⁴ C as a dating tool, but quickly evolving into a method for understanding the carbon cycle. These early ¹⁴ CO 2 measurements immediately demonstrated the existence of an “Atom Bomb Effect,” as well as an “Industrial Effect.” These two gigantic tracer experi...

The rapidly expanding and energy intensive production from the Canadian oil sands, one of the largest oil reserves globally, accounts for almost 12 % of Canada’s greenhouse gas emissions according to inventories. Developing approaches for evaluating reported methane (CH4) emission is crucial for developing effective mitigation policies, but only on...

Radiocarbon data used in ''Radiocarbon bomb-peak signal in tree-rings from the tropical Andes register low latitude atmospheric dynamics in the Southern Hemisphere''

South American tropical climate is strongly related to the tropical low-pressure belt associated with the South American monsoon system. Despite its central societal role as a modulating agent of rainfall in tropical South America, its long-term dynamical variability is still poorly understood. Here we combine a new (and world’s highest) tree-ring...

Background Networks of tower-based CO 2 mole fraction sensors have been deployed by various groups in and around cities across the world to quantify anthropogenic CO 2 emissions from metropolitan areas. A critical aspect in these approaches is the separation of atmospheric signatures from distant sources and sinks (i.e., the background) from local...

Rationale A combination of stable carbon (δ¹³C) and hydrogen (δ²H) isotope ratios and carbon content (% C) was evaluated as a rapid, low‐cost analytical approach to authenticate bioplastics, complementing existing radiocarbon (¹⁴C) and Fourier transform‐infrared (FTIR) analytical methods. Methods Petroleum‐ and bio‐based precursor materials and in...

To understand the Korean Peninsula's carbon dioxide (CO 2) emissions and sinks as well as those of the surrounding region, we used 70 flask-air samples collected during May 2014 to August 2016 at Anmyeondo (AMY; 36.53 • N, 126.32 • E; 46 m a.s.l.) World Meteorological Organization (WMO) Global Atmosphere Watch (GAW) station , located on the west co...

Background Networks of tower-based CO2 mole fraction sensors have been deployed in and around cities across the world to quantify anthropogenic CO2 emissions from metropolitan areas. A critical aspect in these approaches is the separation of atmospheric signatures from distant sources and sinks (i.e., the background) from local emissions and biogen...

Background Networks of tower-based CO2 mole fraction sensors have been deployed in and around cities across the world to quantify anthropogenic CO2 emissions from metropolitan areas. A critical aspect in these approaches is the separation of atmospheric signatures from distant sources and sinks (i.e., the background) from local emissions and biogen...

Global fossil fuel carbon dioxide (FFCO2) emissions will be dictated to a great degree by the trajectory of emissions from urban areas. Conventional methods to quantify urban FFCO2 emissions typically rely on self-reported economic/energy activity data transformed into emissions via standard emission factors. However, uncertainties in these traditi...

The large amount of carbon stored in trees and soils of the Amazon rain forest is under pressure from land use as well as climate change. Therefore, various efforts to monitor greenhouse gas exchange between the Amazon forest and the atmosphere are now ongoing, including regular vertical profile (surface to 4.5 km) greenhouse gas measurements acros...

Abstract. To understand Korea's carbon dioxide (CO₂) emissions and sinks as well as those of the surrounding region, we used 70 flask-air samples collected during May 2014 to August 2016 at Anmyeondo (AMY, 36.53° N, 126.32° E; 46 m a.s.l.) World Meteorological Organization (WMO) Global Atmosphere Watch (GAW) station, located on the west...

Acid-alkali-acid (AAA) pretreatment is widely used to clean terrestrial plant macrofossil samples for radiocarbon ( ¹⁴ C) dating. There is wide variation amongst laboratories in the AAA method details and less rigorous AAA pretreatment is often used on fragile or small samples. Yet there is little evidence as to the efficacy of the different method...

To meet the aspirations of the Paris Agreement, deep and rapid cuts in greenhouse gas (GHG) emissions are required. Since cities are both the epicentres of anthropogenic GHG emissions and often more progressive than states and nations in enacting policies to curb emissions, there is considerable value in developing atmospheric observational and mod...

Atmospheric carbon monoxide (CO) is a key player in global atmospheric chemistry and a regulated pollutant in urban areas. Oxidation of volatile organic compounds (VOCs) is an important component of the global CO budget and has also been hypothesized to contribute substantially to the summertime urban CO budget. In principle, stable isotopic analys...

The Hikurangi subduction margin, New Zealand, has not produced large subduction earthquakes within the short written historic period (~180 years) and the potential of the plate interface to host large (M > 7) to great (M > 8) earthquakes and tsunamis is poorly constrained. The geological record of past subduction earthquakes offers a method for ass...

Urban areas contribute approximately three-quarters of fossil fuel derived CO2 emissions, and many cities have enacted emissions mitigation plans. Evaluation of the effectiveness of mitigation efforts will require measurement of both the emission rate and its change over space and time. The relative performance of different emission estimation meth...

We assimilate multiple trace gas species within a single high-resolution Bayesian inversion system to optimize CO2ff emissions for individual source sectors. Starting with carbon monoxide (CO), an atmospheric trace gas with fairly well-known emissions, we use emission factors of CO and CO2ff (called RCO) defined for each source sector to enable us...

As part of a geological survey in southwest mainland New Caledonia, potsherds were recorded in the profiles at four coastal sites. Subsequent archaeological investigations at two of these sites have allowed us to diversify the ceramic data and show them to be local variants of Podtanean, Puen, and Plum ceramic types. These are characteristic of pro...

Atmospheric carbon monoxide (CO) is a regulated pollutant in urban centers. Oxidation of volatile organic compounds (VOCs) has been hypothesized to contribute substantially to the summertime urban CO budget. We performed measurements of CO stable isotopes on air samples from three sites in and around Indianapolis, USA over three summers to investig...

Annually resolved (varved) lake sequences are important palaeoenvironmental archives as they offer a direct incremental dating technique for high-frequency reconstruction of environmental and climate change. Despite the importance of these records, establishing a robust chronology and quantifying its precision and accuracy (estimations of error) re...

Current bottom up estimates of 'CO2' emission fluxes are based on a mixture of direct and indirect flux estimates relying to varying degrees on regulatory or self-reported data. Hence, it is important to use additional, independent information to assess biases and lower the flux uncertainty. We explore the use of a self-organizing map (SOM) as a to...

We present 60 years of Δ14CO2 measurements from Wellington, New Zealand (41° S, 175° E). The record has been extended and fully revised. New measurements have been used to evaluate the existing record and to replace original measurements where warranted. This is the earliest direct atmospheric Δ14CO2 record and records the rise of the 14C bomb spik...

We present measurements of CO mole fraction and CO stable isotopes (δ13CO and δC18O) in air during the winters of 2013–14 and 2014–15 at tall tower sampling sites in and around Indianapolis, USA. A tower located upwind of the city was used to quantitatively remove the background CO signal, allowing for the first unambiguous isotopic characterizatio...

A twelve-station tower-based observation network measuring CO2, CH4, and CO was deployed in and around the Indianapolis, IN metropolitan area as part of the Indianapolis Flux Experiment (INFLUX). Measurements began in 2010 and the full network was deployed by 2013. Observations were made at heights ranging from 39 to 136 m above ground level using...

The INFLUX experiment has taken multiple approaches to estimate the carbon dioxide (CO 2 ) flux in a domain centered on the city of Indianapolis, Indiana. One approach, Hestia, uses a bottom-up technique relying on a mixture of activity data, fuel statistics, direct flux measurement and modeling algorithms. A second uses a Bayesian atmospheric inve...

We assess the detectability of city emissions via a tower-based greenhouse gas (GHG) network, as part of the Indianapolis Flux (INFLUX) experiment. By examining afternoon-averaged results from a network of carbon dioxide (CO2), methane (CH4), and carbon monoxide (CO) mole fraction measurements in Indianapolis, Indiana for 2011-2013, we quantify spa...

To effectively address climate change, aggressive mitigation policies need to be implemented to reduce greenhouse gas emissions. Anthropogenic carbon emissions are mostly generated from urban environments, where human activities are spatially concentrated. Improvements in uncertainty determinations and precision of measurement techniques are critic...

The objective of the Indianapolis Flux Experiment (INFLUX) is to develop, evaluate and improve methods for measuring greenhouse gas (GHG) emissions from cities. INFLUX's scientific objectives are to quantify CO2 and CH4 emission rates at 1 km2 resolution with a 10% or better accuracy and precision, to determine whole-city emissions with similar ski...

We outline the methodology for detection of carbon dioxide (CO2) leaks to the atmosphere from carbon capture and storage (CCS) using measurements of radiocarbon in CO2. The radiocarbon method can unambiguously identify recently added fossil-derived CO2 such as CCS leaks due to the very large isotopic difference between radiocarbon-free fossil deriv...

We present 60 years of Δ¹⁴CO2 measurements from Wellington, New Zealand (41° S, 175° E). The record has been extended and fully revised. New measurements have been used to evaluate the existing record and to replace original measurements where warranted. This is the earliest atmospheric Δ¹⁴CO2 record and records the rise of the ¹⁴C "bomb spike", th...

Significance The 1,000 largest power plants comprise 22% of total global fossil fuel CO 2 emissions, making them an obvious target for regulating and reducing emissions. The success of existing and upcoming regulations and emission trading schemes requires reliable monitoring and verification of emissions, preferably using independent, objective ev...

Radiocarbon in CO2 (14CO2) measurements can aid in discriminating between fast (<1 year) and slower (>5-10 years) cycling of C between the atmosphere and the terrestrial biosphere due to the 14C disequilibrium between atmospheric and terrestrial C. However, 14CO2 in the atmosphere is typically much more strongly impacted by fossil fuel emissions of...

Measurements of CO2 fluxes in temperate climates have shown that urban areas are a net source of CO2 and that photosynthetic CO2 uptake is generally not sufficient to offset local CO2 emissions. However, little is known about the role of vegetation in cities where biogenic CO2 uptake is not limited to a 2–8 months growing season. This study used th...

This chapter begins by summarizing some of the recent changes in the global carbon (C) cycle, contrasting patterns that exist today with those of the past several hundred years. With this backdrop, the chapter then examines the overall distribution of C isotopes as a framework for understanding the global C cycle and the changes that are happening...

We examine the utility of tree ring 14C archives for detecting long-term changes in fossil CO2 emissions from a point source. Trees assimilate carbon from the atmosphere during photosynthesis, in the process faithfully recording the average atmospheric 14C content in each new annual tree ring. Using 14C as a proxy for fossil CO2, we examine interan...

Based on a uniquely dense network of surface towers measuring continuously the atmospheric concentrations of greenhouse gases (GHGs), we developed the first comprehensive monitoring systems of CO2 emissions at high resolution over the city of Indianapolis. The urban inversion evaluated over the 2012-2013 dormant season showed a statistically signif...

We examine the utility of tree ring 14C archives for detecting long term changes in fossil CO2 emissions from a point source. Trees assimilate carbon from the atmosphere during photosynthesis, in the process faithfully recording the average atmospheric 14C content in each new annual tree ring. Using 14C as a proxy for fossil CO2, we examine interan...

Combining atmospheric Δ14CO2 data sets from different networks or laboratories requires secure knowledge on their compatibility. In the present study, we compare Δ14CO2 results from the Heidelberg low-level counting (LLC) laboratory to 12 international accelerator mass spectrometry (AMS) laboratories using distributed aliquots of five pure CO2 samp...

This article describes a new capability for high-precision 14C measurement of CO2 from air at the Rafter Radiocarbon Laboratory, GNS Science, New Zealand. We evaluate the short-term within-wheel repeatability and long-term between-wheel repeatability from measurements of multiple aliquots of control materials sourced from whole air. Samples are typ...

A detailed description is given of the 0.5 MV tandem accelerator mass spectrometry (AMS) system for 10Be, 14C, 26Al, installed in early 2010 at GNS Science, New Zealand. Its design follows that of previously commissioned Compact 14C-only AMS (CAMS) systems based on the Pelletron tandem accelerator. The only basic departure from that design is an ex...

Abstract We report the CH4 emission flux from the city of Indianapolis, IN, the site of the Indianapolis Flux Experiment (INFLUX) project for developing, assessing, and improving top-down and bottom-up approaches for quantifying urban greenhouse gas emissions. Using an aircraft-based mass balance approach, we find that the average CH4 emission rate...

The Indianapolis Flux Experiment (INFLUX) aims to develop and assess methods for quantifying urban greenhouse gas emissions. Here we use CO2, 14CO2 and CO measurements from tall towers around Indianapolis, USA to determine urban total CO2, the fossil fuel derived CO2 component (CO2ff) and CO enhancements relative to background measurements. When a...

Urban environments are the primary contributors to global anthropogenic carbon emissions. Because much of the growth in CO2 emissions will originate from cities, there is a need to develop, assess, and improve measurement and modeling strategies for quantifying and monitoring greenhouse gas emissions from large urban centers. In this study the unce...

Atmospheric radiocarbon (14C) represents an important observational constraint on emissions of fossil-fuel derived carbon into the atmosphere due to the absence of 14C in fossil fuel reservoirs. The high sensitivity and precision that accelerator mass spectrometry (AMS) affords in atmospheric 14C analysis has greatly increased the potential for usi...

Urban environments are the primary contributors to global anthropogenic carbon emissions. Because much of the growth in CO2 emissions will originate from cities, there is a need to develop, assess and improve measurement and modeling strategies for quantifying and monitoring greenhouse gas emissions from large urban centers. In this study the uncer...

We use the Kapuni Gas Treatment Plant to examine methodologies for atmospheric monitoring of point source fossil fuel CO2 (CO2ff) emissions. The Kapuni plant, located in rural New Zealand, removes CO2 from locally extracted natural gas and vents that CO2 to the atmosphere, at a rate of ~0.1 Tg carbon per year. The plant is located in a rural dairy...

The Indianapolis Flux Experiment (INFLUX) aims at quantifying emissions of anthropogenic carbon using top-down methods and process-based information (Hestia) at very high resolution over the city of Indianapolis (IN). At present, 9 sensors measuring continuously atmospheric mixing ratios of GHG have been deployed, with additional flask samples of i...

New Zealand’s National Isotope Centre, including the Rafter Radiocarbon Laboratory, has upgraded its AMS system from a 6 MV EN-Tandem AMS to a new generation 0.5 MV NEC Extended Compact AMS (XCAMS) system. Current precisions represent approximately an order of magnitude improvement during the AMS era – from 1–2% more than 20 years ago to ∼0...

Atmospheric radiocarbon (14CO) represents an important observational constraint on emissions of fossil-fuel derived carbon into the atmosphere due to the absence of 14CO in fossil fuel reservoirs. The high sensitivity and precision that accelerator mass spectrometry (AMS) affords in atmospheric 14CO analysis has greatly increased the potential for...

The radiocarbon content of whole air provides a theoretically ideal and now observationally proven tracer for recently added fossil-fuel-derived CO2 in the atmosphere (C-ff). Over large industrialized land areas, determination of C-ff also constrains the change in CO2 due to uptake and release by the terrestrial biosphere. Here, we review the devel...

A workshop on atmospheric radiocarbon measurements was held in conjunction with the 21st International Radiocarbon conference in July 2012. The main topics were intercomparison of measurements of C-14 in atmospheric CO2, the potential for use of gas standards for atmospheric C-14 measurements, reporting of uncertainties, and expansion of intercompa...