Publications by authors named "Ciais P"

Record breaking atmospheric methane growth rates were observed in 2020 and 2021 (15.2±0.5 and 17.

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In 2023, the CO growth rate was 3.37 ± 0.11 ppm at Mauna Loa, which was 86% above that of the previous year and hit a record high since observations began in 1958, while global fossil fuel CO emissions only increased by 0.

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The resistance of the Figaro Taguchi Gas Sensor (TGS) decreases when exposed to reducing gas enhancements. TGS gas response can be characterized by comparing measured resistance to a reference resistance, representative of sampling in identical environmental conditions but with no reducing gas enhancement. Thus, this resistance ratio (RR) allows for characterization of reducing gas response, independent of other environmental effects.

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China's commitment to carbon neutrality by 2060 relies on the Land Use, Land-Use Change, and Forestry (LULUCF) sector, with forestation targets designed to enhance carbon removal. However, the exact sequestration potential of these initiatives remains uncertain due to differing accounting conventions between national inventories and scientific assessments. Here, we reconcile both estimates and reassess LULUCF carbon fluxes up to 2100, using a spatially explicit bookkeeping model, state-of-the-art historical data, and national forestation targets.

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Urban greening (UG) affects local climate by altering surface energy balance, while long-term UG cooling potential, patterns, and contribution to curbing urban warming remain unclear. Here, we designed an novel statistical model to evaluate the cooling potential of UG (CPUG) and created the first CPUG map for China. By exploring the trends in observed and simulated urban surface temperatures (UST), we quantified the CPUG of 0.

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Unleashing the land sector's potential for climate mitigation requires purpose-driven changes in land management. However, contributions of past management changes to the current global and regional carbon cycles remain unclear. Here, we use vegetation modelling to reveal how a portfolio of ecological restoration policies has impacted China's terrestrial carbon balance through developing counterfactual 'no-policy' scenarios.

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Article Synopsis
  • Landscape fragmentation can lead to both increases and decreases in wildfire burned area (BA), but the reasons for these opposing effects are not fully understood.
  • A study using a land-fire model linked road density to fragmentation edge effects, finding that fragmentation reduced global BA by an average of -1.5%, but increased BA by over 20% in recently deforested tropical regions.
  • The impact of fragmentation on BA varied with population density, showing a decrease in some areas while indicating higher intensity fires, suggesting that fire severity traits might not be directly related to the amount of BA.
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Understanding microbial adaptation is crucial for predicting how soil carbon dynamics and global biogeochemical cycles will respond to climate change. This study employs the DEMENT model of microbial decomposition, along with empirical mutation and dispersal rates, to explore the roles of mutation and dispersal in the adaptation of soil microbial populations to shifts in litter chemistry, changes that are anticipated with climate-driven vegetation dynamics. Following a change in litter chemistry, mutation generally allows for a higher rate of litter decomposition than dispersal, especially when dispersal predominantly introduces genotypes already present in the population.

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Article Synopsis
  • * There are big differences in climate risks if we exceed temperature limits versus if we stay within them, including effects on sea levels and ice.
  • * To prevent dangerous climate changes, we need to find ways to remove a lot of carbon dioxide from the atmosphere, but this could be hard and expensive to do, meaning we need to act quickly to cut emissions instead.
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Microbial carbon use efficiency (CUE) affects the fate and storage of carbon in terrestrial ecosystems, but its global importance remains uncertain. Accurately modeling and predicting CUE on a global scale is challenging due to inconsistencies in measurement techniques and the complex interactions of climatic, edaphic, and biological factors across scales. The link between microbial CUE and soil organic carbon relies on the stabilization of microbial necromass within soil aggregates or its association with minerals, necessitating an integration of microbial and stabilization processes in modeling approaches.

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The unprecedented surge in global methane levels has raised global concerns in recent years, casting a spotlight on China as a pivotal emitter. China has taken several actions to curb the methane emissions, but their effects remain unclear. Here, we developed the Global ObservatioN-based system for monitoring Greenhouse GAses for methane (GONGGA-CH) and assimilate GOSAT XCH observations to assess changes in China's methane emissions.

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Alleviating water scarcity is at the core of Sustainable Development Goal 6. Yet the timing of water scarcity in its onset and possible relief in different regions of the world due to climate change and changing human population dynamics remains poorly investigated. Here we assess the timing of the first emergence of water scarcity (FirstWS) and disappearance of water scarcity (EndWS), by using ensembles of simulations with six Global Hydrological Models under two representative concentration pathways (i.

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Water resources play a crucial role in the global water cycle and are affected by human activities and climate change. However, the impacts of hydropower infrastructures on the surface water extent and volume cycle are not well known. We used a multi-satellite approach to quantify the surface water storage variations over the 2000-2020 period and relate these variations to climate-induced and anthropogenic factors over the whole basin.

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Global impervious surface area (ISA) has more than doubled over the last three decades, but the associated carbon emissions resulting from the depletion of pre-existing land carbon stores remain unknown. Here, we report that the carbon losses from biomass and top soil (0-30 cm) due to global ISA expansion reached 46-75 Tg C per year over 1993-2018, accounting for 3.7-6.

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The extreme dry and hot 2015/16 El Niño episode caused large losses in tropical live aboveground carbon (AGC) stocks. Followed by climatic conditions conducive to high vegetation productivity since 2016, tropical AGC are expected to recover from large losses during the El Niño episode; however, the recovery rate and its spatial distribution remain unknown. Here, we used low-frequency microwave satellite data to track AGC changes, and showed that tropical AGC stocks returned to pre-El Niño levels by the end of 2020, resulting in an AGC sink of Pg C year during 2014-2020.

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Heat released from soil organic carbon (SOC) decomposition (referred to as microbial heat hereafter) could alter the soil's thermal and hydrological conditions, subsequently modulate SOC decomposition and its feedback with climate. While understanding this feedback is crucial for shaping policy to achieve specific climate goal, it has not been comprehensively assessed. This study employs the ORCHIDEE-MICT model to investigate the effects of microbial heat, referred to as heating effect, focusing on their impacts on SOC accumulation, soil temperature and net primary productivity (NPP), as well as implication on land-climate feedback under two CO emissions scenarios (RCP2.

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Permafrost regions contain approximately half of the carbon stored in land ecosystems and have warmed at least twice as much as any other biome. This warming has influenced vegetation activity, leading to changes in plant composition, physiology, and biomass storage in aboveground and belowground components, ultimately impacting ecosystem carbon balance. Yet, little is known about the causes and magnitude of long-term changes in the above- to belowground biomass ratio of plants (η).

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Article Synopsis
  • During dry periods, decreasing soil moisture leads to plant water stress, highlighting the need for better quantification of a critical soil moisture threshold (θ) to improve climate and resource projections.* -
  • By combining satellite data and ground observations, researchers created a global map of θ, finding it averages at 0.19 m/m, with variations based on ecosystem types.* -
  • The study identified key factors influencing θ, such as aridity, leaf area, and soil texture, and noted an increase in the number of stressful days for plants over the last 40 years, which has implications for understanding water stress in ecosystems.*
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Global soil nitrogen (N) cycling remains poorly understood due to its complex driving mechanisms. Here, we present a comprehensive analysis of global soil δN, a stable isotopic signature indicative of the N input-output balance, using a machine-learning approach on 10,676 observations from 2670 sites. Our findings reveal prevalent joint effects of climatic conditions, plant N-use strategies, soil properties, and other natural and anthropogenic forcings on global soil δN.

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Global estimates of the size, distribution, and vulnerability of soil inorganic carbon (SIC) remain largely unquantified. By compiling 223,593 field-based measurements and developing machine-learning models, we report that global soils store 2305 ± 636 (±1 SD) billion tonnes of carbon as SIC over the top 2-meter depth. Under future scenarios, soil acidification associated with nitrogen additions to terrestrial ecosystems will reduce global SIC (0.

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Natural gas is the primary fuel used in U.S. residences, yet little is known about its consumption patterns and drivers.

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Although substantial advances in predicting the ecological impacts of global change have been made, predictions of the evolutionary impacts have lagged behind. In soil ecosystems, microbes act as the primary energetic drivers of carbon cycling; however, microbes are also capable of evolving on timescales comparable to rates of global change. Given the importance of soil ecosystems in global carbon cycling, we assess the potential impact of microbial evolution on carbon-climate feedbacks in this system.

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Climate change-induced precipitation anomalies during extremely wet years (EWYs) result in substantial nitrogen losses to aquatic ecosystems (N). Still, the extent and drivers of these losses, and effective mitigation strategies have remained unclear. By integrating global datasets with well-established crop modeling and machine learning techniques, we reveal notable increases in N, ranging from 22 to 56%, during historical EWYs.

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