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A re-assessment of the global carbon budget shows the natural land sink is substantially smaller than previously estimated, indicating emerging impacts of climate change on the evolution of the carbon sinks.

Accelerated storage of terrestrial carbon during the slow warming period (1998–2012) can be predominantly attributed to lower land-use emissions due to decreased tropical forest loss and increased afforestation in the northern temperate regions.

Estimates of carbon budgets compatible with limiting warming to below specific temperature limits are reviewed, and reasons underlying their differences discussed along with their respective strengths and limitations.

The extreme hot and dry conditions of 2023 reduced soil respiration and enhanced net forest carbon sequestration in Canada, offsetting wildfire emissions, according to satellite-based and in situ observations of CO₂ fluxes.

The fate of the carbon locked away in soil is uncertain, and there are vast differences between models. Here the authors apply observational, spatio-temporal constraints on carbon turnover projections and find that uncertainty in estimations of carbon dynamics are reduced by 50%.

The only way to stabilize Earth's climate is to stabilize the concentration of greenhouse gases in the atmosphere, but future changes in the carbon cycle might make this more difficult than has been thought.

The impact of land-use and cover-change (LUCC) on ecosystem carbon stock in China is poorly known due to large biases in existing databases. Here the authors develop a new LUCC database with corrected false signals and reveal that forest expansion is the dominant driver of China’s recent carbon sink.

Efforts to control climate change require the stabilization of atmospheric carbon dioxide concentrations. An assessment of the trends in sources and sinks of atmospheric carbon dioxide suggests that the sinks are not keeping up with the increase in carbon dioxide emissions, but uncertainties are still large.

Observed daily changes in CO₂ emissions from across the globe reveal the sectors and countries where pandemic-related emissions declines were most pronounced in 2020.

Earth system model simulations illustrate that agricultural nitrogen fertilization significantly enhances the amplitude of land-atmosphere CO₂ exchange, with a magnitude comparable to that of CO₂ fertilization.

Analysis of observations and model projections provides large-scale emergent constraints on the extent of CO₂ fertilization, with estimated increases in gross primary productivity for both high-latitude and extratropical ecosystems under elevated atmospheric CO₂ concentrations.

Growth in CO₂ emissions has slowed since the Paris Agreement 5 years ago. The COVID-19 pandemic has caused a drop in emissions of about 7% in 2020 relative to 2019, but strong policy is needed to address underlying drivers and to sustain a decline in global emissions beyond the current crisis.

The authors combine climate simulations with observations to estimate carbon budgets which are better constrained and find they are more than 10% larger than the mean value from CMIP6 models.

The model–inventory discrepancy in net land-use carbon emissions mainly results from conceptual differences in estimating anthropogenic forest sinks. A revised disaggregation of global land model results allows greater comparability with inventories.

Satellite records combined with global ecosystem models show a persistent and widespread greening over 25–50% of the global vegetated area; less than 4% of the globe is browning. CO₂ fertilization explains 70% of the observed greening trend.

A linear relationship between the sensitivity of tropical land carbon storage to warming and the sensitivity of the annual growth rate of atmospheric CO₂ to tropical temperature anomalies provides a tight constraint on the sensitivity of tropical land carbon to climate change.

The global net land sink is relatively well constrained. However, the responsible drivers and above/below-ground partitioning are highly uncertain. Model issues regarding turnover of individual plant and soil components are responsible.

Accurately assessing emissions reductions for various greenhouse gases to stay within temperature targets is important. Here, an adaptive approach, based solely on observations and not on model projections, allows quantification of emissions reductions required to achieve any temperature target.

COVID-19 pandemic lockdowns have altered global energy demands. Using government confinement policies and activity data, daily CO₂ emissions have decreased by ~17% to early April 2020 against 2019 levels; annual emissions could be down by 7% (4%) if normality returns by year end (mid-June).

Changes in the leaf area index alter the distribution of heat and moisture. The change in energy partitioning related to leaf area, increasing latent and decreasing sensible fluxes over the observational period 1982–2016, is moderated by plant functional type and background climate.

Records show that tropical water availability rather than temperature appears to have been increasingly controlling the interannual variability of the terrestrial carbon cycle over the past 59 years.

The relationship between terrestrial carbon sinks and atmospheric modes of variability remains uncertain. Here, the authors show that the coupling of the North Atlantic Oscillation and East-Atlantic patterns explains variations in the European CO₂sink from 1982 to 2012.

Northern Hemisphere photosynthesis is thought to respond positively to temperature variations, yet the strength of this relationship may change over time. Here, using a combination of satellite data and models, the authors assess the temporal change of this relationship over the past three decades.

Increasing variability of net biome production over recent decades may be due to climate change and points to destabilization of the carbon–climate system.

Analysis of peatland carbon accumulation over the last millennium and its association with global-scale climate space indicates an ongoing carbon sink into the future, but with decreasing strength as conditions warm.

Carbon loss from forests occurs through deforestation or the degradation of existing forest. The loss of forest area in the Brazilian Amazon was higher in 2019 than following drought and an El Niño event in 2015, yet degradation drove three times more biomass loss than deforestation from 2010 to 2019.

The carbon balance in Southeast Asia is highly uncertain. Here, the authors show that land use changes and occurrence of strong El Niño control decadal shifts in the carbon balance of this region.

If CO₂ emissions after 2015 do not exceed 200 GtC, climate warming after 2015 will fall below 0.6 °C in 66% of CMIP5 models, according to an analysis based on combining a simple climate–carbon-cycle model with estimated ranges for key climate system properties.

Greening—increasing leaf area index—affects regional climate in a number of contradictory ways. The net global effect is now revealed to be cooling that has offset the equivalent of 12% of global land-surface warming over the past 30 years.

A failure to recognize the factors behind continued emissions growth could limit the world’s ability to shift to a pathway consistent with 1.5 °C or 2 °C of global warming. Continued support for low-carbon technologies needs to be combined with policies directed at phasing out the use of fossil fuels.

Satellite and atmospheric observations show that the rate of net biome productivity has accelerated over the warming ‘hiatus’ period (1998–2012). This net gain results from reduced respiration, rather than increased primary productivity.

Nature-based climate solutions are widely incorporated into climate change mitigation plans and need firm scientific foundations. Through literature review and expert elicitation, this analysis shows that for some major pathways there is strong support, while for others their efficacy remains uncertain.

Microbial carbon use efficiency (CUE) is crucial for carbon storage, but its variability is difficult to capture due to inconsistent measurements and complex interactions. This perspective proposes integrating diverse data and models to improve CUE in carbon cycle models

Considering the combined effects of CO₂ fertilization and climate change drivers on plant physiology leads to a modest increase in simulated European forest transpiration in spite of the effects of CO₂-induced stomatal closure.

The source of what seems to be an anomalous increase in atmospheric methane concentrations about 5,000 years ago compared to methane levels during previous interglacial periods has puzzled researchers. Possible explanations for the rise in methane levels include very early agricultural activity. Climate and wetland simulations of global methane levels over the last glacial cycle now suggest that the increase in methane concentrations can be explained by natural changes in the Earth's orbital configuration, with enhanced emissions in the Southern Hemisphere tropics linked to precession-induced modification of seasonal precipitation

The Paris Agreement has increased the incentive to verify reported anthropogenic carbon dioxide emissions with independent Earth system observations. Reliable verification requires a step change in our understanding of carbon cycle variability.

Including passive CO₂ uptake as an anthropogenic removal in greenhouse gas accounting systems could undermine the Paris Agreement; measures to address this include acknowledging the need for Geological Net Zero and disaggregated accounting for carbon sinks.

Uncertainties and subjective choices affecting remaining carbon budgets should be fully considered when applying them to international and national climate policies.

Widespread but contrasting delayed responses of ecosystem productivity to spring warmth across northern ecosystems is inferred from satellite data, with higher areal fractions of adverse effects than beneficial effects.

The net balance of terrestrial biogenic greenhouse gases produced as a result of human activities and the climatic impact of this balance are uncertain; here the net cumulative impact of the three greenhouse gases, methane, nitrous oxide and carbon dioxide, on the planetary energy budget from 2001 to 2010 is a warming of the planet.

The long-term record of atmospheric carbon dioxide growth rate shows that the sensitivity of this growth rate to tropical temperature variability has increased by a factor of about two in the past five decades, and was greater when tropical land regions experienced drier conditions, implying that moisture regulates this sensitivity.

A study of how temperature and water availability fluctuations affect the carbon balance of land ecosystems reveals different controls on local and global scales, implying that spatial climate covariation drives the global carbon cycle response.