Rapid Analysis of Drugs: A Pilot Surveillance System To Detect Changes in the Illicit Drug Supply To Guide Timely Harm Reduction Responses - Eight Syringe Services Programs, Maryland, November 2021-August 2022.

A record number of 2,912 drug overdose deaths occurred in Maryland during the 12-month period July 1, 2020-June 30, 2021. Illicitly manufactured fentanyl, fentanyl analogs, or both* were involved in 84% of these deaths.† Timely identification of illicit drug market changes (e.g., fentanyl rapidly replacing heroin) could improve the public health response, specifically communications about risks for novel psychoactive substances. During November 19, 2021-August 31, 2022, the National Institute of Standards and Technology (NIST)§ tested 496 deidentified drug paraphernalia samples that staff members collected at eight Maryland syringe services programs (SSPs), also known as needle exchange programs,¶ in partnership with the Maryland Department of Health Center for Harm Reduction Services (CHRS).** All test results were available within 48 hours. Among the 496 paraphernalia samples collected, 367 (74.0%) tested positive for an opioid, and 364 (99.2%) of these samples contained fentanyl or fentanyl analogs. Approximately four fifths of fentanyl-positive samples also tested positive for the veterinary medicine xylazine, a sedative that when combined with opioids might increase the potential for fatal respiratory depression and soft tissue infections when injected (1). For 248 of the 496 samples, SSP participants also completed a questionnaire about the drugs they had intended to purchase. Among the 212 participants who had intended to buy an opioid, 87.7% were exposed to fentanyl, fentanyl analogs, or both, and 85.8% were unknowingly exposed to xylazine. Results improved awareness of fentanyl and xylazine among SSP staff members and galvanized efforts to enhance SSPs' wound care services for participants experiencing soft tissue injuries possibly associated with injecting xylazine. Rapid analysis of drug paraphernalia can provide timely data on changing illicit drug markets that can be used to mitigate the harms of drug use more effectively.

Ten facts about land systems for sustainability.

Land use is central to addressing sustainability issues, including biodiversity conservation, climate change, food security, poverty alleviation, and sustainable energy. In this paper, we synthesize knowledge accumulated in land system science, the integrated study of terrestrial social-ecological systems, into 10 hard truths that have strong, general, empirical support. These facts help to explain the challenges of achieving sustainability in land use and thus also point toward solutions. The 10 facts are as follows: 1) Meanings and values of land are socially constructed and contested; 2) land systems exhibit complex behaviors with abrupt, hard-to-predict changes; 3) irreversible changes and path dependence are common features of land systems; 4) some land uses have a small footprint but very large impacts; 5) drivers and impacts of land-use change are globally interconnected and spill over to distant locations; 6) humanity lives on a used planet where all land provides benefits to societies; 7) land-use change usually entails trade-offs between different benefits-"win-wins" are thus rare; 8) land tenure and land-use claims are often unclear, overlapping, and contested; 9) the benefits and burdens from land are unequally distributed; and 10) land users have multiple, sometimes conflicting, ideas of what social and environmental justice entails. The facts have implications for governance, but do not provide fixed answers. Instead they constitute a set of core principles which can guide scientists, policy makers, and practitioners toward meeting sustainability challenges in land use.

Greenhouse Gas Emissions and Management Practices that Affect Emissions in US Rice Systems.

Previous reviews have quantified factors affecting greenhouse gas (GHG) emissions from Asian rice ( L.) systems, but not from rice systems typical for the United States, which often vary considerably particularly in practices (i.e., water and carbon management) that affect emissions. Using meta-analytic and regression approaches, existing data from the United States were examined to quantify GHG emissions and major practices affecting emissions. Due to different production practices, major rice production regions were defined as the mid-South (Arkansas, Texas, Louisiana, Mississippi, and Missouri) and California, with emissions being evaluated separately. Average growing season CH emissions for the mid-South and California were 194 (95% confidence interval [CI] = 129-260) and 218 kg CH ha season (95% CI = 153-284), respectively. Growing season NO emissions were similar between regions (0.14 kg NO ha season). Ratoon cropping (allowing an additional harvestable crop to grow from stubble after the initial harvest), common along the Gulf Coast of the mid-South, had average CH emissions of 540 kg CH ha season (95% CI = 465-614). Water and residue management practices such as alternate wetting and drying, and stand establishment method (water vs. dry seeding), and the amount of residue from the previous crop had the largest effect on growing season CH emissions. However, soil texture, sulfate additions, and cultivar selection also affected growing season CH emissions. This analysis can be used for the development of tools to estimate and mitigate GHG emissions from US rice systems and other similarly mechanized systems in temperate regions.

Identification of Aboriginal and Torres Strait Islander status by general practice registrars: Confidence and associations.

BACKGROUND: Identification of Aboriginal and Torres Strait Islander status in healthcare settings is essential for the delivery of culturally appropriate care. Under-identification is common and practitioner confidence is a known barrier. OBJECTIVE: The objective of this research was to document the self-reported confidence of general practice registrars in identifying the Aboriginal and Torres Strait Islander status of their patients, and associations of this confidence. METHODS: This research used cross-sectional analysis of survey and patient encounter data of general practice registrars training across five Australian states. RESULTS: Of the 698 registrars (97.5% response rate) who participated in the study, 74.5% had a high level of confidence in identifying a patient's Aboriginal and Torres Strait Islander status. Older and more senior registrars had significantly greater confidence. There was also a significant association with the registrars' training provider. DISCUSSION: More than a quarter of registrars reported low confidence for this basic consultation skill. Our findings will inform general prac-tice vocational training and continuing professional development, and reinforce the importance of a comprehensive, system-wide approach to the identification of patients' Aboriginal or Torres Strait Islander status.

Continuity of care in general practice vocational training: prevalence, associations and implications for training.

Continuity of care is a defining characteristic of general practice. Practice structures may limit continuity of care experience for general practice registrars (trainees). This study sought to establish prevalence and associations of registrars' continuity of care. We performed an analysis of an ongoing cohort study of Australian registrars' clinical consultations. Primary outcome factors were 'Upstream' continuity (having seen the patient prior to the index consultation) and 'Downstream' continuity (follow-up organised post-index consultation). Independent variables were registrar, practice, patient, consultation and educational factors. 400 registrars recorded 48,114 consultations. 43% of patients had seen the registrar pre-index consultation, and 49% had follow-up organised. 'Upstream' continuity associations included registrar seniority, Australian medical qualification, practice billing policy, smaller practice size, registrar's previous training in the practice, chronic disease and older, female patients (but not registrar full-time/part-time status). Associations of 'Downstream' continuity included non-Australian qualification, billing, chronic disease and the patient having seen the registrar previously. Consultations prompting follow-up were more complex: longer duration, involving more problems and generating more learning goals. There was, however, evidence for limited educational utility of this 'continuity'. In our study, continuity of care in Australian registrars' training experience is modest. Associations are complex, but may inform initiatives to increase in-training continuity.

The recording of Aboriginal and Torres Strait Islander status in general practice clinical records: a cross-sectional study.

OBJECTIVES: To document the frequency of recording of Aboriginal and Torres Strait Islander status in general practice (GP) clinical records and to establish associations of this recording. METHODS: Cross-sectional analysis of recording of patients' Aboriginal and Torres Strait Islander status in GP clinical records from GP training practices in four Australian states. RESULTS: Of the 9,704 clinical records examined, the patients' Aboriginal and Torres Strait Islander status had been documented in 5,165 (53.2%). Higher rates of recording were associated with older patient age, practices outside a major city, patients who were not new to the practice and the patient being Aboriginal and Torres Strait Islander. In encounters with Aboriginal and Torres Strait Islander patients, the patient's status had been documented in 82% of records. Those attending larger practices were less likely to have had their status recorded. CONCLUSIONS: This is the first report of Aboriginal and Torres Strait Islander status recording in GP clinical records. Almost 20% of Aboriginal and Torres Strait Islander patients did not have their status recorded in the clinical record, with indications that recording may be unsystematic. IMPLICATIONS: Our findings reinforce the need for a systematic approach to identification of Aboriginal and Torres Strait Islander status in general practice and will inform policy and practice in this important area.

Clinical encounters of Australian general practice registrars with Aboriginal and Torres Strait Islander patients.

OBJECTIVE: General practice is central to Aboriginal and Torres Strait Islander health care, and this area is a core element of Australian general practice (GP) training. We aimed to describe the prevalence, nature and associations of GP registrar encounters with Aboriginal and Torres Strait Islander patients. METHODS: A cross-sectional analysis from a cohort study of GP registrars' clinical consultations 2010-2013. Registrars record demographic, clinical and educational details of consecutive patient encounters. Multivariable associations were tested with logistic regression. RESULTS: A total of 592 registrars contributed data from 69,188 consultations. Encounters with Aboriginal and Torres Strait Islander patients comprised 1.0% of consultations. Significant positive associations included younger patient age; new patient to the registrar; lower socioeconomic status of practice location; non-urban practice setting; more problems managed; and follow-up arranged. A greater proportion of Aboriginal and Torres Strait Islander patients' problems were psychological/social and a lesser proportion were cardiovascular. Consultation duration did not differ between the two groups Conclusions: GP registrars encounter Aboriginal and Torres Strait Islander patients less than do established GPs. Our results suggest possible variability in registrar experience of Aboriginal and Torres Strait Islander health. IMPLICATIONS: Our findings will inform training of a culturally and clinically competent workforce in this area.

Investigation of fatigue by Australian general practice registrars: a cross-sectional study.

INTRODUCTION: Fatigue is the most common undifferentiated problem presenting in general practice. Previous studies have shown that this presentation leads to multiple investigations. There is no published literature describing the management of patients with fatigue by general practice (GP) registrars. AIM: To document the investigation-ordering behaviour of GP registrars in managing patients with a new diagnosis of unexplained fatigue. METHODS: This was a cross-sectional analysis of data from Registrar Clinical Encounters in Training (ReCEnT), an ongoing cohort study of GP registrars' consultations. We established the prevalence of new diagnoses of unexplained fatigue and associations with that diagnosis, the rate of test ordering and the number and types of investigations ordered. RESULTS: 644 registrars contributed data from 68 986 encounters. In 0.78% of patient encounters, a new diagnosis of unexplained fatigue was made. Pathology was ordered in 78.4% of these problems (versus 18.1% in non-fatigue problems), at a rate of 488 tests per 100 new fatigue problems. DISCUSSION: Our study suggests that unexplained fatigue elicits a non-rational approach to test ordering by registrars. These findings contribute to the understanding of GP registrar management of fatigue, and undifferentiated presentations more broadly, and suggest educational approaches to improve practice, including dealing with uncertainty.

Test ordering in an evidence free zone: Rates and associations of Australian general practice trainees' vitamin D test ordering.

RATIONALE, AIMS AND OBJECTIVES: Indiscriminate health screening is increasingly seen as being problematic. In particular, vitamin D testing rates are increasing rapidly despite recommendations against population screening. The purpose of this study was to determine the level of vitamin D testing among family practice/general practitioner (GP) trainees and to establish associations of this testing. METHODS: Cross-sectional analysis of data from the ReCEnT (Registrars Clinical Encounters in Training) cohort study. The setting was GP practices in four Australian states. Data from 60 consecutive consultations per trainee were recorded each 6-month training term (up to four terms). RESULTS: Vitamin D tests were ordered in 726 (1.0%) of encounters (n = 69 412). Vitamin D test ordering was significantly associated with patients being older, female and non-English speaking. Trainees were more likely to test if they worked in a completely bulk-billing practice (i.e. a practice without any patient payment), if more problems were dealt with, more pathology tests were ordered in the consultation and if a lipid profile was ordered. They were less likely to test if they sought in-consultation advice or information. The most common reasons for testing were 'check-up' and 'health maintenance'. CONCLUSIONS: In this first report of associations of vitamin D testing in the GP setting, we found that non-targeted vitamin D testing (testing inconsistent with current guidelines) is widespread in GP trainees' practice. Adoption of more rational testing approaches is needed.

Anticholinergic burden in older women: not seeing the wood for the trees?

OBJECTIVES: To identify medicines contributing to and describe predictors of anticholinergic burden among community-dwelling older Australian women. DESIGN, SETTING AND PARTICIPANTS: Retrospective longitudinal analysis of data from the Australian Longitudinal Study on Women's Health linked to Pharmaceutical Benefits Scheme medicines data from 1 January 2008 to 30 December 2010; for 3694 women born in 1921-1926. MAIN OUTCOME MEASURES: Anticholinergic burden calculated from Anticholinergic Drug Scale (ADS) scores derived from ADS levels (0 to 3) for all medicines used by each woman, summed over each 6-month period (semester), medicines commonly used by women with high semester ADS scores (defined as 75th percentile of scores). RESULTS: 1126 women (59.9%) used at least one medicine with anticholinergic properties. The median ADS score was 4 or 5 across all semesters. Most anticholinergic medicines used by women who had a high anticholinergic burden (ADS score, ≥ 9) had a low anticholinergic potency (ADS level 1). Increasing age, cardiovascular disease, and number of other medicines used were predictive of a higher anticholinergic burden. CONCLUSIONS: A high anticholinergic medicines burden in this group was driven by the use of multiple medicines with lower anticholinergic potency rather than the use of medicines with higher potency. This is a novel and important finding for clinical practice as doctors would readily identify the risk of a high anticholinergic burden for patients using high potency medicines, but may be less likely to identify this risk for users of multiple medicines with low anticholinergic potency.

How we use patient encounter data for reflective learning in family medicine training.

INTRODUCTION: Consulting with patients is the core learning activity of Australian family medicine (general practice/GP) training, providing a rich source of reflective learning for trainees. We have developed a reflective learning program for postgraduate vocational trainees based on clinical encounters. METHODS: The Registrar Clinical Encounters in Training (ReCEnT) program is an educational program documenting GP trainees' consultations in five Australian GP training providers. Trainees record patient demographics, consultation details, problems managed, management practices and educational factors from sixty consecutive consultations per six-month training term. Trainees receive a detailed feedback report comparing individual data to aggregated trainee data and national GP data. RESULTS: The patient encounter system provides multiple opportunities for reflective learning across a number of domains of exposure and practice. Reflection can occur during completion of the encounter form; as self-reflection on the feedback report; as facilitated reflection with the GP trainer and medical educator; and as part of integration of data into teaching. We have identified areas for further development, including enhancing the reflective skills of trainees and trainers. CONCLUSION: The ReCEnT patient encounter program provides a rich platform for reflective learning for vocational trainees and supports development of skills in lifelong learning.

Family medicine trainees' clinical experience of chronic disease during training: a cross-sectional analysis from the registrars' clinical encounters in training study.

BACKGROUND: A broad case-mix in family physicians' (general practitioners', GPs') vocational trainee experience is deemed essential in producing competent independent practitioners. It is suggested that the patient-mix should include common and significant conditions and be similar to that of established GPs. But the content of contemporary GP trainees' clinical experience in training is not well-documented. In particular, how well trainees' experience reflects changing general practice demographics (with an increasing prevalence of chronic disease) is unknown. We aimed to establish levels of trainees' clinical exposure to chronic disease in training (and associations of this exposure) and to establish content differences in chronic disease consultations (compared to other consultations), and differences in trainees' actions arising from these consultations. METHODS: A cross-sectional analysis from the Registrars' Clinical Encounters in Training (ReCEnT) study, a cohort study of GP registrars' (trainees') consultations in four Australian GP training organisations. Trainees record detailed data from 60 consecutive consultations per six-month training term. Diagnoses/problems encountered are coded using the International Classification of Primary Care-2 PLUS (ICPC-2 PLUS). A classification system derived from ICPC-2 PLUS was used to define diagnoses/problems as chronic/non-chronic disease. The outcome factor for analyses was trainees' consultations in which chronic disease was encountered. Independent variables were a range of patient, trainee, practice, consultation and educational factors. RESULTS: Of 48,112 consultations (of 400 individual trainees), 29.5% included chronic disease problems/diagnoses. Associations of a consultation including chronic disease were the patient being older, male, and having consulted the trainee previously, and the practice routinely bulk-billing (not personally charging) patients. Consultations involving a chronic disease lasted longer, dealt with more problems/diagnoses, and were more likely to result in specialist referrals and trainees generating a personal learning goal. They were associated with less pathology tests being ordered. CONCLUSIONS: Trainees saw chronic disease less frequently than have established GPs in comparable studies. The longer duration and more frequent generation of learning goals in chronic disease-containing consultations suggest trainees may find these consultations particularly challenging. Our findings may inform the design of measures aimed at increasing the chronic disease component of trainees' patient-mix.

Testing and screening for chlamydia in general practice: a cross-sectional analysis.

OBJECTIVES: Chlamydia screening is widely advocated. General practice registrars are an important stage of clinical behaviour development. This study aimed to determine rates of, and factors associated with, registrars' chlamydia testing including asymptomatic screening. METHODS: A cross-sectional analysis of data from Registrars Clinical Encounters in Training (ReCEnT), a cohort study of registrars' consultations. Registrars record details of 60 consecutive consultations in each GP-term of training. Outcome factors were chlamydia testing, asymptomatic screening and doctor-initiated screening. RESULTS: Testing occurred in 2.5% of 29,112 consultations (398 registrars) and in 5.8% of patients aged 15-25. Asymptomatic screening comprised 47.5% of chlamydia tests, and 55.6% of screening tests were doctor-initiated. Chlamydia testing was associated with female gender of doctor and patient, younger patient age, and patients new to doctor or practice. Asymptomatic screening was associated with practices where patients incur no fees, and in patients new to doctor or practice. Screening of female patients was more often doctor-initiated. CONCLUSIONS: GP registrars screen for chlamydia disproportionately in younger females and new patients. IMPLICATIONS: Our findings highlight potential opportunities to improve uptake of screening for chlamydia, including targeted education and training for registrars, campaigns targeting male patients, and addressing financial barriers to accessing screening services.

Problems managed by Australian general practice trainees: results from the ReCenT (Registrar Clinical Encounters in Training) study.

UNLABELLED: BACKGROUND Previous studies have found that general practitioner (GP) trainees (registrars) see a different spectrum of clinical problems compared to trainers, including less chronic disease and more acute minor illness. Our aim was to describe the case mix of first-term Australian GP trainees. METHODS: This was a cross-sectional analysis of trainee consultations. Descriptive analyses were used to report patient demographics and the number and type of problems managed. RESULTS: Two-hundred-and-three trainees provided data on 36182 consultations and 55740 problems. Overall, 60.7% of patients seen were female and 56.2% were new to the trainee. Trainees managed a mean of 154.1 problems per 100 encounters. Problems managed most commonly were respiratory (23.9 per 100 encounters), general/unspecified (21.8) and skin (16.4). New problems comprised 51.5% of the total, and 22.4% of problems were chronic diseases. CONCLUSION: Trainees gain reasonably broad exposure overall in terms of patient demographics and problems managed. In comparison to established GPs, trainees managed the same mean number of problems, but the nature of problems managed was different, with more new patients, more new problems and less chronic disease. Our findings have significant implications for GP training in Australia.

Multi-scale geospatial agroecosystem modeling: a case study on the influence of soil data resolution on carbon budget estimates.

The development of effective measures to stabilize atmospheric CO2 concentration and mitigate negative impacts of climate change requires accurate quantification of the spatial variation and magnitude of the terrestrial carbon (C) flux. However, the spatial pattern and strength of terrestrial C sinks and sources remain uncertain. In this study, we designed a spatially-explicit agroecosystem modeling system by integrating the Environmental Policy Integrated Climate (EPIC) model with multiple sources of geospatial and surveyed datasets (including crop type map, elevation, climate forcing, fertilizer application, tillage type and distribution, and crop planting and harvesting date), and applied it to examine the sensitivity of cropland C flux simulations to two widely used soil databases (i.e. State Soil Geographic-STATSGO of a scale of 1:250,000 and Soil Survey Geographic-SSURGO of a scale of 1:24,000) in Iowa, USA. To efficiently execute numerous EPIC runs resulting from the use of high resolution spatial data (56m), we developed a parallelized version of EPIC. Both STATSGO and SSURGO led to similar simulations of crop yields and Net Ecosystem Production (NEP) estimates at the State level. However, substantial differences were observed at the county and sub-county (grid) levels. In general, the fine resolution SSURGO data outperformed the coarse resolution STATSGO data for county-scale crop-yield simulation, and within STATSGO, the area-weighted approach provided more accurate results. Further analysis showed that spatial distribution and magnitude of simulated NEP were more sensitive to the resolution difference between SSURGO and STATSGO at the county or grid scale. For over 60% of the cropland areas in Iowa, the deviations between STATSGO- and SSURGO-derived NEP were larger than 1MgCha(-1)yr(-1), or about half of the average cropland NEP, highlighting the significant uncertainty in spatial distribution and magnitude of simulated C fluxes resulting from differences in soil data resolution.

Evaluation of three field-based methods for quantifying soil carbon.

Three advanced technologies to measure soil carbon (C) density (g C m(-2)) are deployed in the field and the results compared against those obtained by the dry combustion (DC) method. The advanced methods are: a) Laser Induced Breakdown Spectroscopy (LIBS), b) Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS), and c) Inelastic Neutron Scattering (INS). The measurements and soil samples were acquired at Beltsville, MD, USA and at Centro International para el Mejoramiento del Maíz y el Trigo (CIMMYT) at El Batán, Mexico. At Beltsville, soil samples were extracted at three depth intervals (0-5, 5-15, and 15-30 cm) and processed for analysis in the field with the LIBS and DRIFTS instruments. The INS instrument determined soil C density to a depth of 30 cm via scanning and stationary measurements. Subsequently, soil core samples were analyzed in the laboratory for soil bulk density (kg m(-3)), C concentration (g kg(-1)) by DC, and results reported as soil C density (kg m(-2)). Results from each technique were derived independently and contributed to a blind test against results from the reference (DC) method. A similar procedure was employed at CIMMYT in Mexico employing but only with the LIBS and DRIFTS instruments. Following conversion to common units, we found that the LIBS, DRIFTS, and INS results can be compared directly with those obtained by the DC method. The first two methods and the standard DC require soil sampling and need soil bulk density information to convert soil C concentrations to soil C densities while the INS method does not require soil sampling. We conclude that, in comparison with the DC method, the three instruments (a) showed acceptable performances although further work is needed to improve calibration techniques and (b) demonstrated their portability and their capacity to perform under field conditions.

Multi-year lags between forest browning and soil respiration at high northern latitudes.

High-latitude northern ecosystems are experiencing rapid climate changes, and represent a large potential climate feedback because of their high soil carbon densities and shifting disturbance regimes. A significant carbon flow from these ecosystems is soil respiration (R(S), the flow of carbon dioxide, generated by plant roots and soil fauna, from the soil surface to atmosphere), and any change in the high-latitude carbon cycle might thus be reflected in R(S) observed in the field. This study used two variants of a machine-learning algorithm and least squares regression to examine how remotely-sensed canopy greenness (NDVI), climate, and other variables are coupled to annual R(S) based on 105 observations from 64 circumpolar sites in a global database. The addition of NDVI roughly doubled model performance, with the best-performing models explaining ∼62% of observed R(S) variability. We show that early-summer NDVI from previous years is generally the best single predictor of R(S), and is better than current-year temperature or moisture. This implies significant temporal lags between these variables, with multi-year carbon pools exerting large-scale effects. Areas of decreasing R(S) are spatially correlated with browning boreal forests and warmer temperatures, particularly in western North America. We suggest that total circumpolar R(S) may have slowed by ∼5% over the last decade, depressed by forest stress and mortality, which in turn decrease R(S). Arctic tundra may exhibit a significantly different response, but few data are available with which to test this. Combining large-scale remote observations and small-scale field measurements, as done here, has the potential to allow inferences about the temporal and spatial complexity of the large-scale response of northern ecosystems to changing climate.

Climate mitigation and the future of tropical landscapes.

Land-use change to meet 21st-century demands for food, fuel, and fiber will depend on many interactive factors, including global policies limiting anthropogenic climate change and realized improvements in agricultural productivity. Climate-change mitigation policies will alter the decision-making environment for land management, and changes in agricultural productivity will influence cultivated land expansion. We explore to what extent future increases in agricultural productivity might offset conversion of tropical forest lands to crop lands under a climate mitigation policy and a contrasting no-policy scenario in a global integrated assessment model. The Global Change Assessment Model is applied here to simulate a mitigation policy that stabilizes radiative forcing at 4.5 W m(-2) (approximately 526 ppm CO(2)) in the year 2100 by introducing a price for all greenhouse gas emissions, including those from land use. These scenarios are simulated with several cases of future agricultural productivity growth rates and the results downscaled to produce gridded maps of potential land-use change. We find that tropical forests are preserved near their present-day extent, and bioenergy crops emerge as an effective mitigation option, only in cases in which a climate mitigation policy that includes an economic price for land-use emissions is in place, and in which agricultural productivity growth continues throughout the century. We find that idealized land-use emissions price assumptions are most effective at limiting deforestation, even when cropland area must increase to meet future food demand. These findings emphasize the importance of accounting for feedbacks from land-use change emissions in global climate change mitigation strategies.

Temperature-associated increases in the global soil respiration record.

Soil respiration, R(S), the flux of microbially and plant-respired carbon dioxide (CO(2)) from the soil surface to the atmosphere, is the second-largest terrestrial carbon flux. However, the dynamics of R(S) are not well understood and the global flux remains poorly constrained. Ecosystem warming experiments, modelling analyses and fundamental biokinetics all suggest that R(S) should change with climate. This has been difficult to confirm observationally because of the high spatial variability of R(S), inaccessibility of the soil medium and the inability of remote-sensing instruments to measure R(S) on large scales. Despite these constraints, it may be possible to discern climate-driven changes in regional or global R(S) values in the extant four-decade record of R(S) chamber measurements. Here we construct a database of worldwide R(S) observations matched with high-resolution historical climate data and find a previously unknown temporal trend in the R(S) record after accounting for mean annual climate, leaf area, nitrogen deposition and changes in CO(2) measurement technique. We find that the air temperature anomaly (the deviation from the 1961-1990 mean) is significantly and positively correlated with changes in R(S). We estimate that the global R(S) in 2008 (that is, the flux integrated over the Earth's land surface over 2008) was 98 +/- 12 Pg C and that it increased by 0.1 Pg C yr(-1) between 1989 and 2008, implying a global R(S) response to air temperature (Q(10)) of 1.5. An increasing global R(S) value does not necessarily constitute a positive feedback to the atmosphere, as it could be driven by higher carbon inputs to soil rather than by mobilization of stored older carbon. The available data are, however, consistent with an acceleration of the terrestrial carbon cycle in response to global climate change.