Global covariation of forest age transitions with the net carbon balance.

Forest age transitions are critical in shaping the global carbon balance, yet their influence on carbon stocks and fluxes remains poorly quantified. Here we analyse global forest age dynamics from 2010 to 2020 using the Global Age Mapping Integration v2.0 dataset, alongside satellite-derived aboveground carbon (AGC) and atmospheric inversion-derived net CO flux data.

First detection of industrial hydrogen emissions using high precision mobile measurements in ambient air.

Projections towards 2050 of the global hydrogen (H) demand indicate an eight-fold increase in present-day hydrogen consumption. Leakage during production, transport, and consumption therefore presents a large potential for increases in the atmospheric hydrogen burden. Although not a greenhouse gas itself, hydrogen has important indirect climate effects, and the Global Warming Potential of H is estimated to be 12.

Temperature extremes of 2022 reduced carbon uptake by forests in Europe.

The year 2022 saw record breaking temperatures in Europe during both summer and fall. Similar to the recent 2018 drought, close to 30% (3.0 million km) of the European continent was under severe summer drought.

Exploring the potential of Δ17O in CO2 for determining mesophyll conductance.

Mesophyll conductance to CO2 from the intercellular air space to the CO2-H2O exchange site has been estimated using δ18O measurements (gm18). However, the gm18 estimates are affected by the uncertainties in the δ18O of leaf water where the CO2-H2O exchange takes place and the degree of equilibration between CO2 and H2O. We show that measurements of Δ17O (i.

Respiratory loss during late-growing season determines the net carbon dioxide sink in northern permafrost regions.

Warming of northern high latitude regions (NHL, > 50 °N) has increased both photosynthesis and respiration which results in considerable uncertainty regarding the net carbon dioxide (CO) balance of NHL ecosystems. Using estimates constrained from atmospheric observations from 1980 to 2017, we find that the increasing trends of net CO uptake in the early-growing season are of similar magnitude across the tree cover gradient in the NHL. However, the trend of respiratory CO loss during late-growing season increases significantly with increasing tree cover, offsetting a larger fraction of photosynthetic CO uptake, and thus resulting in a slower rate of increasing annual net CO uptake in areas with higher tree cover, especially in central and southern boreal forest regions.

Strong Southern Ocean carbon uptake evident in airborne observations.

The Southern Ocean plays an important role in determining atmospheric carbon dioxide (CO), yet estimates of air-sea CO flux for the region diverge widely. In this study, we constrained Southern Ocean air-sea CO exchange by relating fluxes to horizontal and vertical CO gradients in atmospheric transport models and applying atmospheric observations of these gradients to estimate fluxes. Aircraft-based measurements of the vertical atmospheric CO gradient provide robust flux constraints.

The CO record at the Amazon Tall Tower Observatory: A new opportunity to study processes on seasonal and inter-annual scales.

High-quality atmospheric CO  measurements are sparse in Amazonia, but can provide critical insights into the spatial and temporal variability of sources and sinks of CO . In this study, we present the first 6 years (2014-2019) of continuous, high-precision measurements of atmospheric CO at the Amazon Tall Tower Observatory (ATTO, 2.1°S, 58.

Spring enhancement and summer reduction in carbon uptake during the 2018 drought in northwestern Europe.

We analysed gross primary productivity (GPP), total ecosystem respiration (TER) and the resulting net ecosystem exchange (NEE) of carbon dioxide (CO) by the terrestrial biosphere during the summer of 2018 through observed changes across the Integrated Carbon Observation System (ICOS) network, through biosphere and inverse modelling, and through remote sensing. Highly correlated yet independently-derived reductions in productivity from sun-induced fluorescence, vegetative near-infrared reflectance, and GPP simulated by the Simple Biosphere model version 4 (SiB4) suggest a 130-340 TgC GPP reduction in July-August-September (JAS) of 2018. This occurs over an area of 1.

Global atmospheric CO inverse models converging on neutral tropical land exchange, but disagreeing on fossil fuel and atmospheric growth rate.

We have compared a suite of recent global CO atmospheric inversion results to independent airborne observations and to each other, to assess their dependence on differences in northern extratropical (NET) vertical transport and to identify some of the drivers of model spread. We evaluate posterior CO concentration profiles against observations from the High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER) Pole-to-Pole Observations (HIPPO) aircraft campaigns over the mid-Pacific in 2009-2011. Although the models differ in inverse approaches, assimilated observations, prior fluxes, and transport models, their broad latitudinal separation of land fluxes has converged significantly since the Atmospheric Carbon Cycle Inversion Intercomparison (TransCom 3) and the REgional Carbon Cycle Assessment and Processes (RECCAP) projects, with model spread reduced by 80% since TransCom 3 and 70% since RECCAP.

Global 3-D Simulations of the Triple Oxygen Isotope Signature ΔO in Atmospheric CO.

The triple oxygen isotope signature ΔO in atmospheric CO, also known as its "O excess," has been proposed as a tracer for gross primary production (the gross uptake of CO by vegetation through photosynthesis). We present the first global 3-D model simulations for ΔO in atmospheric CO together with a detailed model description and sensitivity analyses. In our 3-D model framework we include the stratospheric source of ΔO in CO and the surface sinks from vegetation, soils, ocean, biomass burning, and fossil fuel combustion.

Determination of the triple oxygen and carbon isotopic composition of CO from atomic ion fragments formed in the ion source of the 253 Ultra high-resolution isotope ratio mass spectrometer.

Rationale: Determination of δ O values directly from CO with traditional gas source isotope ratio mass spectrometry is not possible due to isobaric interference of C O O on C O O. The methods developed so far use either chemical conversion or isotope equilibration to determine the δ O value of CO . In addition, δ C measurements require correction for the interference from C O O on C O O since it is not possible to resolve the two isotopologues.

Increased water-use efficiency and reduced CO uptake by plants during droughts at a continental-scale.

Severe droughts in the Northern Hemisphere cause widespread decline of agricultural yield, reduction of forest carbon uptake, and increased CO growth rates in the atmosphere. Plants respond to droughts by partially closing their stomata to limit their evaporative water loss, at the expense of carbon uptake by photosynthesis. This trade-off maximizes their water-use efficiency, as measured for many individual plants under laboratory conditions and field experiments.

Changes in surface hydrology, soil moisture and gross primary production in the Amazon during the 2015/2016 El Niño.

The 2015/2016 El Niño event caused severe changes in precipitation across the tropics. This impacted surface hydrology, such as river run-off and soil moisture availability, thereby triggering reductions in gross primary production (GPP). Many biosphere models lack the detailed hydrological component required to accurately quantify anomalies in surface hydrology and GPP during droughts in tropical regions.

Widespread reduction in sun-induced fluorescence from the Amazon during the 2015/2016 El Niño.

The tropical carbon balance dominates year-to-year variations in the CO exchange with the atmosphere through photosynthesis, respiration and fires. Because of its high correlation with gross primary productivity (GPP), observations of sun-induced fluorescence (SIF) are of great interest. We developed a new remotely sensed SIF product with improved signal-to-noise in the tropics, and use it here to quantify the impact of the 2015/2016 El Niño Amazon drought.

Tropical land carbon cycle responses to 2015/16 El Niño as recorded by atmospheric greenhouse gas and remote sensing data.

The outstanding tropical land climate characteristic over the past decades is rapid warming, with no significant large-scale precipitation trends. This warming is expected to continue but the effects on tropical vegetation are unknown. El Niño-related heat peaks may provide a test bed for a future hotter world.

Regional atmospheric CO2 inversion reveals seasonal and geographic differences in Amazon net biome exchange.

Understanding tropical rainforest carbon exchange and its response to heat and drought is critical for quantifying the effects of climate change on tropical ecosystems, including global climate-carbon feedbacks. Of particular importance for the global carbon budget is net biome exchange of CO2 with the atmosphere (NBE), which represents nonfire carbon fluxes into and out of biomass and soils. Subannual and sub-Basin Amazon NBE estimates have relied heavily on process-based biosphere models, despite lack of model agreement with plot-scale observations.

Warm spring reduced carbon cycle impact of the 2012 US summer drought.

The global terrestrial carbon sink offsets one-third of the world's fossil fuel emissions, but the strength of this sink is highly sensitive to large-scale extreme events. In 2012, the contiguous United States experienced exceptionally warm temperatures and the most severe drought since the Dust Bowl era of the 1930s, resulting in substantial economic damage. It is crucial to understand the dynamics of such events because warmer temperatures and a higher prevalence of drought are projected in a changing climate.

A comprehensive estimate of recent carbon sinks in China using both top-down and bottom-up approaches.

Atmospheric inversions use measurements of atmospheric CO2 gradients to constrain regional surface fluxes. Current inversions indicate a net terrestrial CO2 sink in China between 0.16 and 0.

An atmospheric perspective on North American carbon dioxide exchange: CarbonTracker.

We present an estimate of net CO(2) exchange between the terrestrial biosphere and the atmosphere across North America for every week in the period 2000 through 2005. This estimate is derived from a set of 28,000 CO(2) mole fraction observations in the global atmosphere that are fed into a state-of-the-art data assimilation system for CO(2) called CarbonTracker. By design, the surface fluxes produced in CarbonTracker are consistent with the recent history of CO(2) in the atmosphere and provide constraints on the net carbon flux independent from national inventories derived from accounting efforts.