scholarly journals Decadal Variability in Land Carbon Sink Efficiency Reveals Apparent Trend Reversal After 2009

2020 ◽  
Author(s):  
Lei Zhu ◽  
Philippe Ciais ◽  
Ana Bastos ◽  
Ashley P. Ballantyne ◽  
Frederic Chevallier ◽  
...  
Keyword(s):  
Fossil Fuel ◽  
Decadal Variability ◽  
Temporal Dynamics ◽  
Carbon Sink ◽  
Climate Mitigation ◽  
Carbon Sinks ◽  
Carbon Neutrality ◽  
A Value ◽  
Natural Land ◽  
Nationally Determined Contributions

Abstract Background: The climate mitigation target of limiting the temperature increase below 2 °C above the pre-industrial levels requires the efforts from all countries. Tracking the trajectory of the land carbon sink efficiency is thus crucial to evaluate the nationally determined contributions (NDCs). Here, we define the instantaneous land sink efficiency as the ratio of natural land carbon sinks to emissions from fossil fuel and land-use and land-cover change with a value of 1 indicating carbon neutrality to track its temporal dynamics in the past decades.Results: Land sink efficiency has been decreasing during 1957-1990 because of the increased emissions from fossil fuel. After the effect of the Pinatubo eruption diminished (after 1994), the land sink efficiency firstly increased before 2009 and then began to decrease again after 2009. This reversal around 2009 is mostly attributed to changes in land sinks in Latin America in response to climate variations.Conclusions: The decreasing trend of land sink efficiency in the recent years reveals greater challenges in climate change mitigation, and impacts of climate on land carbon sinks need to be accurately quantified to assess the implementation of climate mitigation policies.

scholarly journals Decadal variability in land carbon sink efficiency

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Lei Zhu ◽  
Philippe Ciais ◽  
Ana Bastos ◽  
Ashley P. Ballantyne ◽  
Frederic Chevallier ◽  
...  
Keyword(s):  
Fossil Fuel ◽  
Decadal Variability ◽  
Temporal Dynamics ◽  
Carbon Sink ◽  
Regional Scale ◽  
Climate Impacts ◽  
Climate Mitigation ◽  
Carbon Sinks ◽  
Tropical Regions ◽  
Carbon Neutrality

Abstract Background The climate mitigation target of limiting the temperature increase below 2 °C above the pre-industrial levels requires the efforts from all countries. Tracking the trajectory of the land carbon sink efficiency is thus crucial to evaluate the nationally determined contributions (NDCs). Here, we define the instantaneous land sink efficiency as the ratio of natural land carbon sinks to emissions from fossil fuel and land-use and land-cover change with a value of 1 indicating carbon neutrality to track its temporal dynamics in the past decades. Results Land sink efficiency has been decreasing during 1957–1990 because of the increased emissions from fossil fuel. After the effect of the Mt. Pinatubo eruption diminished (after 1994), the land sink efficiency firstly increased before 2009 and then began to decrease again after 2009. This reversal around 2009 is mostly attributed to changes in land sinks in tropical regions in response to climate variations. Conclusions The decreasing trend of land sink efficiency in recent years reveals greater challenges in climate change mitigation, and that climate impacts on land carbon sinks must be accurately quantified to assess the effectiveness of regional scale climate mitigation policies.

scholarly journals Tapping the potential of NDCs and LT-LEDS to address fossil fuel production

2021 ◽  
Author(s):  
Natalie Jones ◽  
Miquel Muñoz Cabré ◽  
Georgia Piggot ◽  
Michael Lazarus
Keyword(s):  
Climate Change ◽  
Fossil Fuel ◽  
Paris Agreement ◽  
Climate Mitigation ◽  
Window Of Opportunity ◽  
Fuel Production ◽  
Fuel Supply ◽  
Nationally Determined Contributions ◽  
First Time

The need for a managed transition away from fossil fuel production raises the question of whether and how countries are addressing this need in their national communications to the UN Framework Convention on Climate Change (UNFCCC). A previous 2019 analysis of the first round of nationally determined contributions (NDCs) and long-term, low-emissions development strategies (LT-LEDS) found that few countries discussed how they would address fossil fuel production as part of their climate mitigation activities. Here, we examine new and updated NDCs and LT-LEDS, finding a growing number of NDCs and LT-LEDS that address fossil fuel production as part of mitigation. For the first time, several countries incorporate policies and/ or pathways for a managed decline of fossil fuel production. In contrast, many others foresee continued or expanded fossil fuel production, with no mention of efforts to prepare for a transition. Opportunities remain for countries to make better use of NDCs and LT-LEDS to align fossil fuel production with the Paris Agreement, including by more comprehensively reflecting on the equity implications of their plans, as well as addressing how countries plan to diversify their economies, ensure a just transition for workers, and cooperate internationally on a managed wind-down of fossil fuel supply. As COP26 approaches, this window of opportunity is still open, but it is rapidly closing.

scholarly journals The Method of Measuring Carbon Sinks Based on the Changes of oxygen concentration in Forest Canopy

2021 ◽  
Author(s):  
CHANGSHAN XING ◽  
JIANG LV ◽  
YUN SHI
Keyword(s):  
Carbon Dioxide ◽  
Carbon Sequestration ◽  
Oxygen Concentration ◽  
Forest Canopy ◽  
Carbon Sink ◽  
Accurate Method ◽  
Growth Cycle ◽  
Forest Carbon ◽  
Carbon Sinks ◽  
Carbon Neutrality

Abstract Measuring Forest Carbon Sinks is becoming a popular topic as the need of many countries’ carbon neutrality plans. We demonstrate a simple and accurate method of Forest Carbon Sinks measurement. By observing the daily average oxygen concentration in the canopy, we found it presented a parabolic distribution from Spring to Fall in a year. The forest finished the cycle from releasing oxygen and sequestrating carbon dioxide to using oxygen and releasing carbon dioxide in this period. We calculated the carbon sequestration of the forest was 101.39t/hm2/y, the Carbon Sink was 15.09t/hm2/y by calculating the changes of oxygen concentration in a growth cycle, the Carbon Sink is 16.29% of the carbon sequestration.

scholarly journals Pathways of China's PM2.5 air quality 2015–2060 in the context of carbon neutrality

2021 ◽  
Author(s):  
Jing Cheng ◽  
Dan Tong ◽  
Qiang Zhang ◽  
Yang Liu ◽  
Yu Lei ◽  
...  
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
Critical Role ◽  
Climate Mitigation ◽  
Air Pollution Control ◽  
Carbon Neutrality ◽  
Climate Action ◽  
Clean Air ◽  
Near Term ◽  
Who Guideline

ABSTRACT Clean air policies in China have substantially reduced PM2.5 air pollution in recent years, primarily by curbing end-of-pipe emissions. However, further reaching the WHO guideline may instead depend upon the air quality co-benefits of ambitious climate action. Here, we assess pathways of Chinese PM2.5 air quality from 2015 to 2060 under a combination of scenarios which link Global and China's climate mitigation pathways (i.e. global 2°C- and 1.5°C-pathways, NDC pledges, and carbon neutrality goals) to local clean air policies. We find that China can achieve both its near-term climate goals (peak emissions) and PM2.5 air quality annual standard (35 μg/m3) by 2030 by fulfilling its NDC pledges and continuing air pollution control policies. However, the benefits of end-of-pipe control reductions are mostly exhausted by 2030, and reducing PM2.5 exposure of the majority of the Chinese population to below 10 μg/m3 by 2060 will likely require more ambitious climate mitigation efforts such as China's carbon neutrality goals and global 1.5°C-pathways. Our results thus highlight that China's carbon neutrality goals will play a critical role in reducing air pollution exposure to the WHO guideline and protecting public health.

scholarly journals Modelling Tree Growth in Monospecific Forests from Forest Inventory Data

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 753
Author(s):  
Guadalupe Sáez-Cano ◽  
Marcos Marvá ◽  
Paloma Ruiz-Benito ◽  
Miguel A. Zavala
Keyword(s):  
Tree Growth ◽  
Large Scale ◽  
Temporal Dynamics ◽  
Carbon Sink ◽  
Size Variation ◽  
Biotic Interactions ◽  
Richards Equation ◽  
Tree Level ◽  
Forest Inventories ◽  
Large Scale Data

The prediction of tree growth is key to further understand the carbon sink role of forests and the short-term forest capacity on climate change mitigation. In this work, we used large-scale data available from three consecutive forest inventories in a Euro-Mediterranean region and the Bertalanffy–Chapman–Richards equation to model up to a decade’s tree size variation in monospecific forests in the growing stages. We showed that a tree-level fitting with ordinary differential equations can be used to forecast tree diameter growth across time and space as function of environmental characteristics and initial size. This modelling approximation was applied at different aggregation levels to monospecific regions with forest inventories to predict trends in aboveground tree biomass stocks. Furthermore, we showed that this model accurately forecasts tree growth temporal dynamics as a function of size and environmental conditions. Further research to provide longer term prediction forest stock dynamics in a wide variety of forests should model regeneration and mortality processes and biotic interactions.

scholarly journals What can be learned about carbon cycle climate feedbacks from the CO<sub>2</sub> airborne fraction?

2010 ◽  
Vol 10 (16) ◽  
pp. 7739-7751 ◽  
Author(s):  
M. Gloor ◽  
J. L. Sarmiento ◽  
N. Gruber
Keyword(s):  
Land Use ◽  
Fossil Fuel ◽  
Carbon Sink ◽  
Volcanic Eruptions ◽  
Atmospheric Co2 ◽  
Anthropogenic Emissions ◽  
Term Trend ◽  
Decadal Scale ◽  
Long Term Trend

Abstract. The ratio of CO2 accumulating in the atmosphere to the CO2 flux into the atmosphere due to human activity, the airborne fraction AF, is central to predict changes in earth's surface temperature due to greenhouse gas induced warming. This ratio has remained remarkably constant in the past five decades, but recent studies have reported an apparent increasing trend and interpreted it as an indication for a decrease in the efficiency of the combined sinks by the ocean and terrestrial biosphere. We investigate here whether this interpretation is correct by analyzing the processes that control long-term trends and decadal-scale variations in the AF. To this end, we use simplified linear models for describing the time evolution of an atmospheric CO2 perturbation. We find firstly that the spin-up time of the system for the AF to converge to a constant value is on the order of 200–300 years and differs depending on whether exponentially increasing fossil fuel emissions only or the sum of fossil fuel and land use emissions are used. We find secondly that the primary control on the decadal time-scale variations of the AF is variations in the relative growth rate of the total anthropogenic CO2 emissions. Changes in sink efficiencies tend to leave a smaller imprint. Therefore, before interpreting trends in the AF as an indication of weakening carbon sink efficiency, it is necessary to account for trends and variations in AF stemming from anthropogenic emissions and other extrinsic forcing events, such as volcanic eruptions. Using atmospheric CO2 data and emission estimates for the period 1959 through 2006, and our simple predictive models for the AF, we find that likely omissions in the reported emissions from land use change and extrinsic forcing events are sufficient to explain the observed long-term trend in AF. Therefore, claims for a decreasing long-term trend in the carbon sink efficiency over the last few decades are currently not supported by atmospheric CO2 data and anthropogenic emissions estimates.

scholarly journals Global to local impacts on atmospheric CO2 caused by COVID-19 lockdown

2021 ◽  
Author(s):  
Ning Zeng
Keyword(s):  
Fossil Fuel ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Carbon Sink ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Monitoring Systems ◽  
Carbon Cycle Model ◽  
Safe Level ◽  
Small Change

&lt;p&gt;&lt;span&gt;The world-wide lockdown in response to the COVID-19 pandemic in year 2020 led to economic slowdown and large reduction of fossil fuel CO2 emissions 1,2, but it is unclear how much it would reduce atmospheric CO2 concentration, the main driver of climate change, and whether it can be observed. We estimated that a 7.9% reduction in emissions for 4 months would result in a 0.25 ppm decrease in the Northern Hemisphere CO2, an increment that is within the capability of current CO2 analyzers, but is a few times smaller than natural CO2 variabilities caused by weather and the biosphere such as El Nino. We used a state-of-the-art atmospheric transport model to simulate CO2, driven by a new daily fossil fuel emissions dataset and hourly biospheric fluxes from a carbon cycle model forced with observed climate variability. Our results show a 0.13 ppm decrease in atmospheric column CO2 anomaly averaged over 50S-50N for the period February-April 2020 relative to a 10-year climatology. A similar decrease was observed by the carbon satellite GOSAT3. Using model sensitivity experiments, we further found that COVID, the biosphere and weather contributed 54%, 23%, and 23% respectively. In May 2020, the CO2 anomaly continued to decrease and was 0.36 ppm below climatology, mostly due to the COVID reduction and a biosphere that turned from a relative carbon source to carbon sink, while weather impact fluctuated. This seemingly small change stands out as the largest sub-annual anomaly in the last 10 years. Measurements from global ground stations were analyzed. At city scale, on-road CO2 enhancement measured in Beijing shows reduction of 20-30 ppm, consistent with drastically reduced traffic during the lockdown, while station data suggest that the expected COVID signal of 5-10 ppm was swamped by weather-driven variability on multi-day time scales. The ability of our current carbon monitoring systems in detecting the small and short-lasting COVID signal on the background of fossil fuel CO2 accumulated over the last two centuries is encouraging. The COVID-19 pandemic is an unintended experiment whose impact suggests that to keep atmospheric CO2 at a climate-safe level will require sustained effort of similar magnitude and improved accuracy and expanded spatiotemporal coverage of our monitoring systems.&lt;/span&gt;&lt;/p&gt;

A Review of Transport Policies in Support of Climate Actions in Asian Cities and Countries

Earth ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 731-745
Author(s):  
Madan B. Regmi
Keyword(s):  
Climate Change ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Urban Transport ◽  
Transport Sector ◽  
Asian Countries ◽  
Gas Emissions ◽  
Carbon Neutrality ◽  
Asian Cities ◽  
Nationally Determined Contributions

Asia is one of the continents that is the most affected by the impacts of climate change. Asian countries need to take climate actions and mitigate emissions from the urban passenger transport sector. Despite some progress in improving urban mobility in Asian cities, greenhouse gas emissions from the transport sector continue to rise. Policy makers who are responsible for managing mobilities must play a major role in decarbonizing the transport sector. In this context, this paper reviews the efforts of selected Asian countries and cities towards reducing greenhouse gas emissions from the urban transport sector. It will analyze their pledges in the Nationally Determined Contributions submitted to the United Nations Framework Convention on Climate Change and will review their relevant transport sector strategies, policies, and practices. It will also look at trends in transport sector emissions and air pollution in different cities, including the short-term impacts of COVID-19. Lastly, it reviews governance issues and the roles that institutions should play to implement polices to decarbonize transport. Based on this analysis, this paper offers policy suggestions to accelerate actions, enhance cross-sectoral coordination, and move towards carbon neutrality in the transport sector in Asia.

scholarly journals Impact of variable air-sea O<sub>2</sub> and CO<sub>2</sub> fluxes on atmospheric potential oxygen (APO) and land-ocean carbon sink partitioning

2008 ◽  
Vol 5 (3) ◽  
pp. 875-889 ◽  
Author(s):  
C. D. Nevison ◽  
N. M. Mahowald ◽  
S. C. Doney ◽  
I. D. Lima ◽  
N. Cassar
Keyword(s):  
Transport Model ◽  
Atmospheric Transport ◽  
Carbon Sink ◽  
Three Dimensional ◽  
Ecosystem Model ◽  
Accurate Estimate ◽  
Carbon Sinks ◽  
Fossil Carbon ◽  
Ocean Carbon ◽  
Potential Oxygen

Abstract. A three dimensional, time-evolving field of atmospheric potential oxygen (APO ~O2/N2+CO2) was estimated using surface O2, N2 and CO2 fluxes from the WHOI ocean ecosystem model to force the MATCH atmospheric transport model. Land and fossil carbon fluxes were also run in MATCH and translated into O2 tracers using assumed O2:CO2 stoichiometries. The modeled seasonal cycles in APO agree well with the observed cycles at 13 global monitoring stations, with agreement helped by including oceanic CO2 in the APO calculation. The modeled latitudinal gradient in APO is strongly influenced by seasonal rectifier effects in atmospheric transport. An analysis of the APO-vs.-CO2 mass-balance method for partitioning land and ocean carbon sinks was performed in the controlled context of the MATCH simulation, in which the true surface carbon and oxygen fluxes were known exactly. This analysis suggests uncertainty of up to ±0.2 PgC in the inferred sinks due to variability associated with sparse atmospheric sampling. It also shows that interannual variability in oceanic O2 fluxes can cause large errors in the sink partitioning when the method is applied over short timescales. However, when decadal or longer averages are used, the variability in the oceanic O2 flux is relatively small, allowing carbon sinks to be partitioned to within a standard deviation of 0.1 Pg C/yr of the true values, provided one has an accurate estimate of long-term mean O2 outgassing.

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