scholarly journals Tropical Carbon and Water Observed from Above

Eos ◽  
2021 ◽  
Vol 102 ◽  
Author(s):  
John Worden ◽  
Sassan Saatchi ◽  
Anthony Bloom
Keyword(s):  
Tropical Forests ◽  
Carbon Balance ◽  
Global Climate ◽  
Satellite Observations ◽  
Water Fluxes

Satellite observations of carbon balance and water fluxes are changing the role of tropical forests in local and global climate.

scholarly journals The role of phosphorus dynamics in tropical forests – a modeling study using CLM-CNP

2013 ◽  
Vol 10 (8) ◽  
pp. 14439-14473 ◽  
Author(s):  
X. Yang ◽  
P. E. Thornton ◽  
D. M. Ricciuto ◽  
W. M. Post
Keyword(s):  
Nutrient Limitation ◽  
Tropical Forests ◽  
Elevated Co2 ◽  
Field Experiments ◽  
Global Climate ◽  
P Availability ◽  
Tropical Ecosystems ◽  
Model Simulations ◽  
P Limitation

Abstract. Tropical forests play a significant role in the global carbon cycle and global climate. However, tropical carbon cycling and the feedbacks from tropical ecosystems to the climate system remain critical uncertainties in current generation carbon-climate models. One of the major uncertainties comes from the lack of representation of phosphorus (P), the most limiting nutrient in tropical regions. Here we introduce P dynamics and C–N–P interactions into the CLM4-CN model and investigate the role of P cycling in controlling the productivity of tropical ecosystems. The newly developed CLM-CNP model includes all major biological and geochemical processes controlling P availability in soils and the interactions between C, N, and P cycles. Model simulations at sites along a Hawaiian soil chronosequence indicate that the introduction of P limitation greatly improved the model performance at the P-limited site. The model is also able to capture the shift in nutrient limitation along this chronosequence (from N limited to P limited), as shown in the comparison of model simulated plant responses to fertilization with the observed data. Model simulations at Amazonian forest sites show that CLM-CNP is capable of capturing the overall trend in NPP along the P availability gradient. This comparison also suggests a significant interaction between nutrient limitation and land use history. Model experiments under elevated atmospheric CO2 ([CO2]) condition suggest that tropical forest responses to increasing [CO2] will interact strongly with changes in the P cycle. We highlight the importance of two feedback pathways (biochemical mineralization and desorption of secondary mineral P) that can significantly affect P availability and determine the extent of P limitation in tropical forests under elevated [CO2]. Field experiments with elevated CO2 are therefore needed to help quantify these important feedbacks. Predictive modeling of C–P interactions will have important implications for the prediction of future carbon uptake and storage in tropical ecosystems and global climate change.

scholarly journals The Key Role of Warm Rain Parameterization in Determining the Aerosol Indirect Effect in a Global Climate Model

2019 ◽  
Vol 32 (14) ◽  
pp. 4409-4430 ◽  
Author(s):  
Xianwen Jing ◽  
Kentaroh Suzuki ◽  
Takuro Michibata
Keyword(s):  
Indirect Effect ◽  
Formation Process ◽  
Global Climate ◽  
Satellite Observations ◽  
Past Century ◽  
Formation Processes ◽  
Aerosol Indirect Effect ◽  
Warm Rain ◽  
Rain Formation

AbstractGlobal climate models (GCMs) have been found to share the common too-frequent bias in the warm rain formation process. In this study, five different autoconversion schemes are incorporated into a single GCM, to systematically evaluate the warm rain formation processes in comparison with satellite observations and investigate their effects on the aerosol indirect effect (AIE). It is found that some schemes generate warm rain less efficiently under polluted conditions in the manner closer to satellite observations, while the others generate warm rain too frequently. Large differences in AIE are found among these schemes. It is remarkable that the schemes with more observation-like warm rain formation processes exhibit larger AIEs that far exceed the uncertainty range reported in IPCC AR5, to an extent that can cancel much of the warming trend in the past century, whereas schemes with too-frequent rain formations yield AIEs that are well bounded by the reported range. The power-law dependence of the autoconversion rate on the cloud droplet number concentration β is found to affect substantially the susceptibility of rain formation to aerosols: the more negative β is, the more difficult it is for rain to be triggered in polluted clouds, leading to larger AIE through substantial contributions from the wet scavenging feedback. The appropriate use of a droplet size threshold can mitigate the effect of a less negative β. The role of the warm rain formation process on AIE in this particular model has broad implications for others that share the too-frequent rain-formation bias.

scholarly journals The role of phosphorus dynamics in tropical forests – a modeling study using CLM-CNP

2014 ◽  
Vol 11 (6) ◽  
pp. 1667-1681 ◽  
Author(s):  
X. Yang ◽  
P. E. Thornton ◽  
D. M. Ricciuto ◽  
W. M. Post
Keyword(s):  
Tropical Forest ◽  
Nutrient Limitation ◽  
Tropical Forests ◽  
Elevated Co2 ◽  
Global Climate ◽  
P Availability ◽  
Tropical Ecosystems ◽  
Model Simulations ◽  
P Limitation

Abstract. Tropical forests play a significant role in the global carbon cycle and global climate. However, tropical carbon cycling and the feedbacks from tropical ecosystems to the climate system remain critical uncertainties in the current generation of carbon–climate models. One of the major uncertainties comes from the lack of representation of phosphorus (P), currently believed to be the most limiting nutrient in tropical regions. Here we introduce P dynamics and C–N–P interactions into the CLM4-CN (Community Land Model version 4 with prognostic Carbon and Nitrogen) model and investigate the role of P cycling in controlling the productivity of tropical ecosystems. The newly developed CLM-CNP model includes all major biological and geochemical processes controlling P availability in soils and the interactions between C, N, and P cycles. Model simulations at sites along a Hawaiian soil chronosequence indicate that the introduction of P limitation greatly improved the model performance at the P-limited site. The model is also able to capture the shift in nutrient limitation along this chronosequence (from N limited to P limited), as shown in the comparison of model-simulated plant responses to fertilization with the observed data. Model simulations at Amazonian forest sites show that CLM-CNP is capable of capturing the overall trend in NPP (net primary production) along the P availability gradient. This comparison also suggests a significant interaction between nutrient limitation and land use history. Model experiments under elevated atmospheric CO2 ([CO2]) conditions suggest that tropical forest responses to increasing [CO2] will interact strongly with changes in the P cycle. We highlight the importance of two feedback pathways (biochemical mineralization and desorption of secondary mineral P) that can significantly affect P availability and determine the extent of P limitation in tropical forests under elevated [CO2]. Field experiments with elevated CO2 are therefore needed to help quantify these important feedbacks. CO2 doubling model experiments show that tropical forest response to elevated [CO2] can only be predicted if the interactions between C cycle and nutrient dynamics are well understood and represented in models. Predictive modeling of C–nutrient interactions will have important implications for the prediction of future carbon uptake and storage in tropical ecosystems and global climate change.

The Role of Tropical Forests in Supporting Biodiversity and Hydrological Integrity

2005 ◽  
Author(s):  
Ellen M. Douglas ◽  
Kate Sebastian ◽  
Charles J. Vorosmarty ◽  
Stanley Wood ◽  
Kenneth M. Chomitz
Keyword(s):  
Tropical Forests

scholarly journals Transcriptomic and genetic approaches reveal an essential role of the NAC transcription factor SlNAP1 in the growth and defense response of tomato

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Jiao Wang ◽  
Chenfei Zheng ◽  
Xiangqi Shao ◽  
Zhangjian Hu ◽  
Jianxin Li ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Defense Response ◽  
Global Climate ◽  
Plant Responses ◽  
Multiple Stresses ◽  
Bacterial Diseases ◽  
Bacterial Wilt Disease ◽  
Transgenic Lines ◽  
Breeding Target

AbstractWith global climate change, plants are frequently being exposed to various stresses, such as pathogen attack, drought, and extreme temperatures. Transcription factors (TFs) play crucial roles in numerous plant biological processes; however, the functions of many tomato (Solanum lycopersicum L.) TFs that regulate plant responses to multiple stresses are largely unknown. Here, using an RNA-seq approach, we identified SlNAP1, a NAC TF-encoding gene, which was strongly induced by various stresses. By generating SlNAP1 transgenic lines and evaluating their responses to biotic and abiotic stresses in tomato, we found that SlNAP1-overexpressing plants showed significantly enhanced defense against two widespread bacterial diseases, leaf speck disease, caused by Pseudomonas syringae pv. tomato (Pst) DC3000, and root-borne bacterial wilt disease, caused by Ralstonia solanacearum. In addition, SlNAP1 overexpression dramatically improved drought tolerance in tomato. Although the SlNAP1-overexpressing plants were shorter than the wild-type plants during the early vegetative stage, eventually, their fruit yield increased by 10.7%. Analysis of different hormone contents revealed a reduced level of physiologically active gibberellins (GAs) and an increased level of salicylic acid (SA) and abscisic acid (ABA) in the SlNAP1-overexpressing plants. Moreover, EMSAs and ChIP-qPCR assays showed that SlNAP1 directly activated the transcription of multiple genes involved in GA deactivation and both SA and ABA biosynthesis. Our findings reveal that SlNAP1 is a positive regulator of the tomato defense response against multiple stresses and thus may be a potential breeding target for improving crop yield and stress resistance.

Decomposing the time-mean Atlantic Meridional Overturning Circulation and its variability with latitude.

2021 ◽  
Author(s):  
Tomas Jonathan ◽  
Mike Bell ◽  
Helen Johnson ◽  
David Marshall
Keyword(s):  
Global Climate ◽  
Dominant Role ◽  
Meridional Overturning Circulation ◽  
Western Boundary ◽  
Relative Role ◽  
Overturning Circulation ◽  
Near Surface ◽  
Boundary Density ◽  
Meridional Overturning

<p>The Atlantic Meridional Overturning Circulations (AMOC) is crucial to our global climate, transporting heat and nutrients around the globe. Detecting  potential climate change signals first requires a careful characterisation of inherent natural AMOC variability. Using a hierarchy of global coupled model  control runs (HadGEM-GC3.1, HighResMIP) we decompose the overturning circulation as the sum of (near surface) Ekman, (depth-dependent) bottom velocity, eastern and western boundary density components, as a function of latitude. This decomposition proves a useful low-dimensional characterisation of the full 3-D overturning circulation. In particular, the decomposition provides a means to investigate and quantify the constraints which boundary information imposes on the overturning, and the relative role of eastern versus western contributions on different timescales. </p><p>The basin-wide time-mean contribution of each boundary component to the expected streamfunction is investigated as a function of depth, latitude and spatial resolution. Regression modelling supplemented by Correlation Adjusted coRrelation (CAR) score diagnostics provide a natural ranking of the contributions of the various components in explaining the variability of the total streamfunction. Results reveal the dominant role of the bottom component, western boundary and Ekman components at short time-scales, and of boundary density components at decadal and longer timescales.</p>

scholarly journals Reviews and syntheses: Flying the satellite into your model: on the role of observation operators in constraining models of the Earth system and the carbon cycle

2017 ◽  
Vol 14 (9) ◽  
pp. 2343-2357 ◽  
Author(s):  
Thomas Kaminski ◽  
Pierre-Philippe Mathieu
Keyword(s):  
Data Assimilation ◽  
Carbon Cycle ◽  
Automatic Differentiation ◽  
Satellite Observations ◽  
Spectral Radiance ◽  
Special Focus ◽  
Earth System ◽  
The Earth ◽  
Retrieval Scheme

Abstract. The vehicles that fly the satellite into a model of the Earth system are observation operators. They provide the link between the quantities simulated by the model and the quantities observed from space, either directly (spectral radiance) or indirectly estimated through a retrieval scheme (biogeophysical variables). By doing so, observation operators enable modellers to properly compare, evaluate, and constrain their models with the model analogue of the satellite observations. This paper provides the formalism and a few examples of how observation operators can be used in combination with data assimilation techniques to better ingest satellite products in a manner consistent with the dynamics of the Earth system expressed by models. It describes commonalities and potential synergies between assimilation and classical retrievals. This paper explains how the combination of observation operators and their derivatives (linearizations) form powerful research tools. It introduces a technique called automatic differentiation that greatly simplifies both the development and the maintenance of code for the evaluation of derivatives. Throughout this paper, a special focus lies on applications to the carbon cycle.

scholarly journals Climate governance in an international system under conservative hegemony: the role of major powers

2012 ◽  
Vol 55 (spe) ◽  
pp. 9-29 ◽  
Author(s):  
Eduardo Viola ◽  
Matías Franchini ◽  
Thaís Lemos Ribeiro
Keyword(s):  
Climate Change ◽  
International Relations ◽  
Global Climate ◽  
International System ◽  
Exploratory Research ◽  
Climate Governance ◽  
Major Powers ◽  
Common Character ◽  
Do So

In the last five years, climate change has been established as a central civilizational driver of our time. As a result of this development, the most diversified social processes - as well as the fields of science which study them - have had their dynamics altered. In International Relations, this double challenge could be explained as follows: 1) in empirical terms, climate change imposes a deepening of cooperation levels on the international community, considering the global common character of the atmosphere; and 2) to International Relations as a discipline, climate change demands from the scientific community a conceptual review of the categories designed to approach the development of global climate governance. The goal of this article is to discuss in both conceptual and empirical terms the structure of global climate change governance, through an exploratory research, aiming at identifying the key elements that allow understanding its dynamics. To do so, we rely on the concept of climate powers. This discussion is grounded in the following framework: we now live in an international system under conservative hegemony that is unable to properly respond to the problems of interdependence, among which - and mainly -, the climate issue.

scholarly journals International climate change negotiation: the role of Brazil

2019 ◽  
Vol 10 (3) ◽  
pp. 379-395
Author(s):  
Marcela Cardoso Guilles Da Conceição ◽  
Renato de Aragão Ribeiro Rodrigues ◽  
Fernanda Reis Cordeiro ◽  
Fernando Vieira Cesário ◽  
Gracie Verde Selva ◽  
...  
Keyword(s):  
Climate Change ◽  
Global Climate ◽  
International Negotiation ◽  
Climate Change Negotiations ◽  
Essential Condition ◽  
Average Temperature ◽  
Social And Economic Development ◽  
International Climate ◽  
International Climate Change

The increase of greenhouse gases in the atmosphere raises the average temperature of the planet, triggering problems that threaten the survival of humans. Protecting the global climate from the effects of climate change is an essential condition for sustaining life. For this reason, governments, scientists, and society are joining forces to propose better solutions that could well-rounded environmentally, social and economic development relationships. International climate change negotiations involve many countries in establishing strategies to mitigate the problem. Therefore, understanding international negotiation processes and how ratified agreements impact a country is of fundamental importance. The purpose of this paper is to systematize information about how climate negotiations have progressed, detailing key moments and results, analyzing the role that Brazil played in the course of these negotiations and the country’s future perspectives.

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