No-till management is often recognized for its environmental and economic benefits, but its potential to reduce climate warming is still uncertain. Beyond ongoing debate over its effects on soil carbon storage, no-till also leaves plant residue on the surface, which can reflect more sunlight. This increase in surface reflectivity, called albedo, may help mitigate climate change by reducing the energy absorbed by the land. Here, we assessed this climate benefit of no-till across the U.S. Corn Belt using conservation survey records, county-level tillage data, and satellite observations. We found that no-till increased land surface brightness during the dormant season, reducing absorbed solar energy by an estimated 50 grams of CO2 equivalent per square meter per year. Regionally, this could add up to 24 teragrams of CO2 equivalent per year in potential climate benefits. Areas with low adoption, especially those with dark, carbon-rich soils, offer the greatest opportunity for further mitigation.

Although natural climate solutions (NCS) are increasingly deployed within carbon markets and beyond, their climate benefits may be over-estimated due to a lack of accounting for changes in albedo. Here we analyze 172 Afforestation, Reforestation, and Revegetation projects within the voluntary carbon market and find more than 10% occur in places where albedo entirely negates the climate mitigation benefit and a quarter occur in places where albedo halves the mitigation benefit. Yet, the majority of projects are concentrated where albedo changes are expected to be minimal, and 9% of projects occur where albedo would augment the mitigation benefit. New data make albedo accounting possible for the first time, and we outline an iterative approach for incorporating albedo considerations into carbon crediting protocols. Doing so will enable prioritization of projects with greater climate benefit and more accurately quantify credits that may be used to address unabated emissions.

Background Malaria transmission depends on the presence of gametocytes in the peripheral blood of infected human hosts. Understanding malaria infectious reservoirs enables transmission-blocking interventions to target the most important hosts for the disease. This study characterized the distribution of gametocyte carriage as a baseline for clinical evaluation of a Pfs25-based transmission-blocking vaccine candidate in Bagamoyo, Tanzania. Methods A malaria survey was conducted in five villages, between 2022 and 2023. A total of 467 asymptomatic participants; 192 children (5–12 years), 65 adolescents (13–17 years) and 210 adults (18–45 years), were enrolled. Malaria was detected using three methods; Rapid Diagnostic Tests, Light Microscopy, and Quantitative Polymerase Chain Reaction. Geometric mean of the gametocyte density, and weighted arithmetic mean of gametocytes sex ratio were estimated. Results Overall, 23.5% (110/467) of the participants tested positive for malaria parasites, with majority positives (> 92%) being Plasmodium falciparum. The overall gametocytaemia was 5.6%, with percentage positivity of 6.8% (13/192), 6.2% (4/65) 4.3% and (9/210), in children, adolescents and adults, respectively. The geometric mean gametocyte density (gametocytes/µL) was higher in adults (124.6) than in children (71.7) and adolescents (50.5). Regression analysis showed that gametocytes were more likely to be present among male participants than female participants [ORa: 2.79 (95% CI: 1.19–6.59) p = 0.019]. The gametocyte sex ratio in children and adult gametocyte carriers was similar but higher than in adolescents. Conclusion The observed gametocyte densities and distribution across age groups suggest the need for malaria transmission-blocking interventions to target all population, particularly in low transmission settings. The implication of targeting only children may leave residual malaria transmission and re-infection from the left-out groups.

Large across-model spread in simulating land carbon (C) dynamics has been ubiquitously demonstrated in model intercomparison projects (MIPs), and became a major impediment in advancing climate change prediction. Thus, it is imperative to identify underlying sources of the spread. Here, we used a novel matrix approach to analytically pin down the sources of across-model spread in transient peatland C dynamics in response to a factorial combination of two atmospheric CO2 levels and five temperature levels. We developed a matrix-based MIP by converting the C cycle module of eight land models (i.e., TEM, CENTURY4, DALEC2, TECO, FBDC, CASA, CLM4.5 and ORCHIDEE) into eight matrix models. While the model average of ecosystem C storage was comparable to the measurement, the simulation differed largely among models, mainly due to inter-model difference in baseline C residence time. Models generally overestimated net ecosystem production (NEP), with a large spread that was mainly attributed to inter-model difference in environmental scalar. Based on the sources of spreads identified, we sequentially standardized model parameters to shrink simulated ecosystem C storage and NEP to almost none. Models generally captured the observed negative response of NEP to warming, but differed largely in the magnitude of response, due to differences in baseline C residence time and temperature sensitivity of decomposition. While there was a lack of response of NEP to elevated CO2 (eCO2 ) concentrations in the measurements, simulated NEP responded positively to eCO2 concentrations in most models, due to the positive responses of simulated net primary production. Our study used one case study in Minnesota peatland to demonstrate that the sources of across-model spreads in simulating transient C dynamics can be precisely traced to model structures and parameters, regardless of their complexity, given the protocol that all the matrix models were driven by the same gross primary production and environmental variables.

Climate change has been partially mitigated by an increasing net land carbon sink in the terrestrial biosphere; understanding the processes that drive this sink is thus essential for protecting, managing and projecting this important ecosystem service. In this Review, we examine evidence for an enhanced land carbon sink and attribute the observed response to drivers and processes. This sink has doubled from 1.2 ± 0.5 PgC yr−1 in the 1960s to 3.1 ± 0.6 PgC yr−1 in the 2010s. This trend results largely from carbon dioxide fertilization increasing photosynthesis (driving an increase in the annual land carbon sink of >2 PgC globally since 1900), mainly in tropical forest regions, and elevated temperatures reducing cold limitation, mainly at higher latitudes. Continued long-term land carbon sequestration is possible through the end of this century under multiple emissions scenarios, especially if nature-based climate solutions and appropriate ecosystem management are used. A new generation of globally distributed field experiments is needed to improve understanding of future carbon sink potential by measuring belowground carbon release, the response to carbon dioxide enrichment, and long-term shifts in carbon allocation and turnover. The terrestrial biosphere stores carbon in a land carbon sink, offsetting emissions of carbon into the atmosphere. This Review demonstrates that the magnitude of the land carbon sink has increased over time, but that its stability in the future is less clear and depends on climate impacts and effective implementation of nature-based solutions.

Continental North America has been found to be a carbon (C) sink over recent decades by multiple studies employing a variety of estimation approaches. However, several key questions and uncertainties remain with these assessments. Here we used results from an ensemble of 19 state‐of‐the‐art dynamic global vegetation models from the TRENDYv9 project to improve these estimates and study the drivers of its interannual variability. Our results show that North America has been a C sink with a magnitude of 0.37 ± 0.38 (mean and one standard deviation) PgC year −1 for the period 2000–2019 (0.31 and 0.44 PgC year −1 in each decade); split into 0.18 ± 0.12 PgC year −1 in Canada (0.15 and 0.20), 0.16 ± 0.17 in the United States (0.14 and 0.17), 0.02 ± 0.05 PgC year −1 in Mexico (0.02 and 0.02) and 0.01 ± 0.02 in Central America and the Caribbean (0.01 and 0.01). About 57% of the new C assimilated by terrestrial ecosystems is allocated into vegetation, 30% into soils, and 13% into litter. Losses of C due to fire account for 41% of the interannual variability of the mean net biome productivity for all North America in the model ensemble. Finally, we show that drought years (e.g., 2002) have the potential to shift the region to a small net C source in the simulations (−0.02 ± 0.46 PgC year −1 ). Our results highlight the importance of identifying the major drivers of the interannual variability of the continental‐scale land C cycle along with the spatial distribution of local sink‐source dynamics.

Proxy‐based reconstructions of Neogene warm climates are a valuable data source for helping to understand what a future, warmer world may look like. Such insights are especially critical in the Arctic where the fastest rates of warming are underway and likely to continue. In this study, hydrogen isotopes of lignin‐methoxy groups (δ 2 H LM ) from Miocene and Pliocene sub‐fossil wood samples ( N = 43) at six high‐latitude sites (73–80°N) in the Canadian Arctic Archipelago were used to estimate mean δ 2 H values of precipitation and temperature anomalies (ΔT) relative to present. The ΔT estimates ranged from +9.7 to +16.7°C depending on site and epoch and are corroborated by a suite of independent proxy data for most sites, and for one site (Prince Patrick Island) this study provides the first quantitative ΔT estimates. These are conservative estimates as they do not account for the more negative δ 2 H seawater values during the Neogene. These ΔT estimates, along with independent proxy and vegetation data, depict a dramatically warmer version of the Arctic. Some of this warming was likely driven by global atmospheric change and feedbacks that are possible in the modern‐day Arctic. However, transformation of the once‐contiguous Arctic landmass into a dissected archipelago has undoubtedly changed the nature and future warming potential of the Canadian Arctic region. Investigations aimed at disentangling the relative contribution of global versus regional boundary conditions to Neogene Arctic climate warming are needed to understand the extent to which these reconstructions may foreshadow conditions in the future.

Precipitation plays a vital role within the Earth system [...]

In this study, we describe the fossil wood flora from the Chattian (late Oligocene) and Aquitanian (early Miocene) deposits that crop out on the Tym River at Kompasky Bor, Russia. Twenty conifer and angiosperm wood taxa are described and a new fossil wood genus Thujopsoxylon gen. nov. and three new species are established: Thujopsoxylon schneiderianum sp. nov.; Piceoxylon nikitinii sp. nov.; and Crataegoxylon sibiricum sp. nov. The Kompasky Bor flora is important because it is the northernmost Chattian macroflora in the West Siberian Plain so far known and provides constraints on the timing and record of plant taxa migrations between Europe and the West Siberian Plain during the late Paleogene and the early Neogene. The fossil wood and macrofossil taxa are compared to European and other West Siberian Plain floras of similar age to understand the spatial and temporal relationships between these floras. The results of this multivariate analysis indicate floristic exchange between Europe and the West Siberian Plain was not prevalent, but much more pronounced between the West Siberian Plain and the Ural Mountains during the Rupelian and Chattian. Furthermore, elements of the polar broad-leaved deciduous forests appear to have occupied northern Europe and extended into the Ural Mountains and, despite the functionality of the lowland corridors between Europe and the West Siberian Plain, floristic exchange was not pronounced until Miocene time when climate became cooler and drier, signaling the onset of the evolution and development of boreal ecosystems in Europe and the West Siberian Plain.

Metasequoia glyptostroboides, a deciduous gymnosperm, also known as dawn redwood, was thought to be extinct until living members of the species were found in China in 1943. Analyzing the climate response of a transplanted stand of the trees can give insights into their physiological plasticity, into their use in restoration and reforestation, as well as into interpreting the environmental conditions of the geologic past from fossil Metasequoia. An annual ring-width chronology—spanning 1955 to 2010 and based on a stand of 19 M. glyptostroboides trees planted in Secrest Arboretum in northeast Ohio, USA—shows negative correlations with maximum monthly temperatures: with the strongest relationship with February and the warm months of June and July, all significant at the 99% confidence levels. A positive May to June precipitation correlation is the strongest moisture signal (p < 0.05) and the narrowest rings in the chronology occurred during the drought of 1987 to 1988, consistent with one of the warmest and driest Junes on record. These results have implications for the future as climate change affects the native and transplanted range of this species. Future response of this species to a changing climate will depend on the relative rates of warming maximum temperatures in the winter and summer, as well as changing moisture conditions during the summer months.

The overarching science goal of this research project was to analyze Atmospheric Radiation Mission (ARM) observations to increase our understanding of raindrop breakup, coalescence, and evaporation processes in precipitating clouds in order to improve how these processes are represented in cloud resolving models.

© 2019 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).CORRESPONDING AUTHOR: Virendra P. Ghate, vghate@anl.gov

We present a Lagrangian convective transport scheme developed for global chemistry and transport models, which considers the variable residence time that an air parcel spends in convection. This is particularly important for accurately simulating the tropospheric chemistry of short-lived species, e.g., for determining the time available for heterogeneous chemical processes on the surface of cloud droplets. In current Lagrangian convective transport schemes air parcels are stochastically redistributed within a fixed time step according to estimated probabilities for convective entrainment as well as the altitude of detrainment. We introduce a new scheme that extends this approach by modeling the variable time that an air parcel spends in convection by estimating vertical updraft velocities. Vertical updraft velocities are obtained by combining convective mass fluxes from meteorological analysis data with a parameterization of convective area fraction profiles. We implement two different parameterizations: a parameterization using an observed constant convective area fraction profile and a parameterization that uses randomly drawn profiles to allow for variability. Our scheme is driven by convective mass fluxes and detrainment rates that originate from an external convective parameterization, which can be obtained from meteorological analysis data or from general circulation models. We study the effect of allowing for a variable time that an air parcel spends in convection by performing simulations in which our scheme is implemented into the trajectory module of the ATLAS chemistry and transport model and is driven by the ECMWF ERA-Interim reanalysis data. In particular, we show that the redistribution of air parcels in our scheme conserves the vertical mass distribution and that the scheme is able to reproduce the convective mass fluxes and detrainment rates of ERA-Interim. We further show that the estimated vertical updraft velocities of our scheme are able to reproduce wind profiler measurements performed in Darwin, Australia, for velocities larger than 0.6 m s−1. SO2 is used as an example to show that there is a significant effect on species mixing ratios when modeling the time spent in convective updrafts compared to a redistribution of air parcels in a fixed time step. Furthermore, we perform long-time global trajectory simulations of radon-222 and compare with aircraft measurements of radon activity.