Greenhouse gas emissions, inventories and validation

The emission of greenhouse gases has become a very high priority research and environmental policy issue due to their effects on global climate. The knowledge of changes in global atmospheric concentrations of greenhouse gases since the industrial revolution is well documented, and the global budgets are reasonably well known. However, even at this scale there are important uncertainties in the budgets, for example, in the case of methane while the main sources and sinks have been identified, temporal changes in the global average concentrations since the early 1990s are not understood. In the absence of a quantitative explanation with appropriate experimental support, it is clear that current knowledge of the causes of changes in the global methane budget is inadequate to predict the effect of changes in specific emission sectors. In developing control strategies to reduce emissions it is necessary to validate national emissions and their spatial disaggregation. The methodology to underpin such a process is at an early stage of development and is not fully implemented in any country, even though target emission reductions have already been announced. Furthermore, the scale of the emission reductions is large (eg of 60% reductions by 2050 relative to 1990 baseline). There is therefore an urgent requirement for measurement based verification processes to support such challenging emission reductions. In this paper we provide the background in greenhouse gas emissions globally and in the UK followed by examples of approaches to validate emissions at the UK scale and within the regions

Can seasonal and interannual variation in landscape CO2 fluxes be detected by atmospheric observations of CO2 concentrations made at a tall tower?

The coupled numerical weather model WRF-SPA (Weather Research and Forecasting model and Soil-Plant-Atmosphere model) has been used to investigate a 3 yr time series of observed atmospheric CO₂ concentrations from a tall tower in Scotland, UK. Ecosystem-specific tracers of net CO₂ uptake and net CO₂ release were used to investigate the contributions to the tower signal of key land covers within its footprint, and how contributions varied at seasonal and interannual timescales. In addition, WRF-SPA simulated atmospheric CO₂ concentrations were compared with two coarse global inversion models, CarbonTrackerEurope and the National Oceanic and Atmospheric Administration's CarbonTracker (CTE-CT). WRF-SPA realistically modelled both seasonal (except post harvest) and daily cycles seen in observed atmospheric CO₂ at the tall tower (<i>R</i>² = 0.67, rmse = 3.5 ppm, bias = 0.58 ppm). Atmospheric CO₂ concentrations from the tall tower were well simulated by CTE-CT, but the inverse model showed a poorer representation of diurnal variation and simulated a larger bias from observations (up to 1.9 ppm) at seasonal timescales, compared to the forward modelling of WRF-SPA. However, we have highlighted a consistent post-harvest increase in the seasonal bias between WRF-SPA and observations. Ecosystem-specific tracers of CO₂ exchange indicate that the increased bias is potentially due to the representation of agricultural processes within SPA and/or biases in land cover maps. The ecosystem-specific tracers also indicate that the majority of seasonal variation in CO₂ uptake for Scotland's dominant ecosystems (forests, cropland and managed grassland) is detectable in observations within the footprint of the tall tower; however, the amount of variation explained varies between years. The between years variation in detectability of Scotland's ecosystems is potentially due to seasonal and interannual variation in the simulated prevailing wind direction. This result highlights the importance of accurately representing atmospheric transport used within atmospheric inversion models used to estimate terrestrial source/sink distribution and magnitude

A flexible eye-safe lidar instrument for elastic-backscatter and DIAL

Developments in lidar have been driven largely by improvements in two key technologies: lasers and detectors. We describe here a lidar instrument for atmospheric remote sensing using the elastic-backscatter and differential-absorption lidar (DIAL) techniques. The instrument features an all-solid-state laser source combined with a flexible approach to detection providing portability, eye-safe operation and high sensitivity. The system is built around a custom-designed Newtonian telescope with a 0.38 m diameter primary mirror. Laser sources and detectors attach directly to the side of the telescope allowing for flexible customization with a range of equipment. The laser source is based on an optical parametric oscillator (OPO). The OPO is pumped by a neodymiumbased diode-laser pumped solid-state laser and angle-tuned by rotating the nonlinear conversion crystal. This provides a wide range of available wavelengths suitable for lidar within the 1.55 µm to 3.10 µm spectral region, where there exists a relatively high exposure limit for eye safety. The OPO delivers 1 mJ output pulse energy which is expanded and then transmitted coaxially from the telescope. Our goal is to make vertically-resolved measurements of greenhouse gas concentrations using DIAL. The source can rapidly be tuned between the on-line and off-line wavelengths to make a DIAL measurement. The use of the 1.6 µm wavelength region allows for several detection schemes. Whilst photodiode detectors are a very low-cost solution their limited sensitivity restricts the maximum range over which a signal can be detected. We therefore have designed the instrument to support alternative detection schemes including avalanche photodiodes (APDs)

Survival outcomes and interval between lymphoscintigraphy and SLNB in cutaneous melanoma- findings of a large prospective cohort study

Introduction: Sentinel lymph node biopsy (SLNB) in cutaneous melanoma (CM) is performed to identify patient at risk of regional and distant relapse. We hypothesized that timing of lymphoscintigraphy may influence the accuracy of SLNB and patient outcomes. Methods: We reviewed prospective data on patients undergoing SLNB for CM at a large university cancer-center between 2008-2015, examining patient and tumor demographics and time between lymphoscintigraphy (LS) and SLNB. Kaplan-Meier survival analysis assessed disease-specific (DSS) and overall-survival (OS), stratified by timing of LS. Cox multivariate regression analysis assessed independent risk factors for survival. Results: We identified 1015 patients. Median follow-up was 45 months (IQR 26-68 months). Univariate analysis showed a 6.8% absolute DSS (HR 1.6 [1.03-2.48], p= 0.04) benefit and a 10.7% absolute OS (HR 1.64 [1.13-2.38], p=0.01) benefit for patients whose SLNB was performed 12 hours (n=652). Multivariate analysis identified timing of LS as an independent predictor of OS (p=0.007) and DSS (p=0.016) when competing with age, sex, Breslow thickness (BT) and SLN status. No difference in nodal relapse rates (5.2% v 4.6%; p=0.67) was seen. Both groups were matched for age, sex, BT and SLN status. Conclusion: These data have significant implications for SLNB services, suggesting delaying SLNB >12 hours after LS using a Tc99-labelled nanocolloid has a significant negative survival impact for patients and should be avoided. We hypothesise that temporal tracer migration is the underlying cause and advocate further trials investigating alternative, 'stable' tracer-agents

A feasibility study of indocyanine green fluorescence mapping for sentinel lymph node detection in cutaneous melanoma

Objectives: Sentinel lymph node biopsy (SLNB) is standard of care for staging regional LN in AJCC stage IB-IIC melanoma; using dual localization with radiolabelled colloid and blue dye. Combining these gives optimal accuracy; drawbacks include cumulative radiation exposure for healthcare workers, coordination between disciplines and anaphylaxis. An alternative tracer agent is indocyanine green (ICG); an optical enhancer that fluoresces in the near infrared range. This prospective cohort study assesses the feasibility of using ICG as a tracer agent to detect SLN in cutaneous melanoma. Methods: Primary melanoma patients diagnosed with pT1b-pT4b tumours undergoing SLNB were recruited over a 6-month period at a tertiary referral centre. All underwent standard preoperative lymphoscintigraphy (LSG) using 20-40MBq of Tc99radiolabelled nanocolloid plus intraoperative Patent Blue dye (PBD). ICG was administered as a third tracer agent intraoperatively. Results: 62 patients (33M/29F) were recruited; median age was 61 years. Median melanoma Breslow thickness was 1.6mm. 144 specimens containing 135 SLN were excised. Concordance rate for all 3 tracer agents was 88.1%(119/135 LN); that for radioisotope/PBD was 88.2%(95%CI:82.2,93.7). There were no discordance pairs between radioisotope/PBD compared to radioisotope/PBD/ICG. Radioisotope/ICG significantly increased the sensitivity of detecting SLN to 98.5%(95%CI:94.8,99.8); p<0.00001 compared to radioisotope/PBD. Concordance rate of intraoperative ICG drainage pattern with LSG was 22.6%. Conclusion: ICG utilization showed comparable sensitivity with gold standard. Technical challenges e.g. ICG leakage into biopsy field, poor concordance with LSG limits its efficacy in melanoma SLNB. We therefore do not recommend replacing current practice with ICG alone or by using a combination with TC99

Depression: why drugs and electricity are not the answer

The dominant view within mental health services and research suggests that feeling depressed is a kind of medical illness, partially caused by various biological deficits which are somehow corrected by physical interventions. This article critically appraises evidence for the effectiveness and value of antidepressant drugs and electroconvulsive therapy (ECT), the two principle physical treatments recommended for depression. It also describes the negative effects of these interventions and raises concerns about how they impact the brain. We propose an alternative understanding that recognises depression as an emotional and meaningful response to unwanted life events and circumstances. This perspective demands that we address the social conditions that make depression likely and suggests that a combination of politics and common sense needs to guide us in providing help for one another when we are suffering in this way. This alternative view is increasingly endorsed around the world, including by the United Nations, the World Health Organization and service users who have suffered negative consequences of physical treatments that modify brain functions in ways that are not well-understood

Designing withdrawal support services for antidepressant users: Patients’ views on existing services and what they really need

BACKGROUND: Public Health England has recommended that services be put in place to support people who choose to withdraw from antidepressants because of a current gap. This study aims to explore the views of members of online withdrawal peer-support groups about existing healthcare and what additional support is needed. METHODS: The administrators of 15 online support groups for people stopping antidepressants were asked to advertise an online survey to their members. The survey, which was online from May 2021 to April 2022, was completed by 1276 people from 49 countries. RESULTS: 71% of respondents found their doctors' advice unhelpful (57% 'very unhelpful') regarding stopping an antidepressant; the main reasons being 'Recommended a reduction rate that was too quick for me', 'Not familiar enough with withdrawal symptoms to advise me' and 'Suggested stopping antidepressants would not cause withdrawal symptoms'. One in three did not seek advice from their prescriber when deciding whether to withdraw, with the main reasons being 'I felt they would not be supportive' (58%) and 'I felt that they didn't have the expertise to help me' (51%). The most common prescriber responses to those who did seek advice was 'Suggested a quick withdrawal schedule' (56%) and 'Not supportive and offered no guidance' (27%). The most common discontinuation periods recommended by doctors were one month (23%) and two weeks (19%). A range of potential professional services were rated 'very useful', most frequently: 'Access to smaller doses (e.g. tapering strips, liquid, smaller dose tablets) to ensure gradual reduction' (88%) and 'A health professional providing a personalised, flexible reduction plan' (79%). LIMITATIONS: This was a convenience sample, which may have been biased towards people who took longer to withdraw, and experienced more withdrawal symptoms, than antidepressant users in general. Black and ethnic minority people, and people without access to the internet, were underrepresented. CONCLUSIONS: Most participants reported their prescribers were unable to help them safely stop antidepressants, compelling them to turn to online peer-support groups instead. Our findings indicate, in keeping with previous studies, that clinicians require upskilling in safe tapering of antidepressants, and that patients need specialised services to help them stop safely