Developing a regional-scale reef restoration activity for the tropics

2021 ◽  
Vol 21 (4) ◽  
Author(s):  
Mark T. Gibbs
Keyword(s):  
Regional Scale ◽  
Reef Restoration ◽  
The Tropics

scholarly journals Impact of anthropogenic activities on global land oxygen flux

2019 ◽  
Author(s):  
Xiaoyue Liu ◽  
Jianping Huang ◽  
Jiping Huang ◽  
Changyu Li ◽  
Lei Ding
Keyword(s):  
Fossil Fuel ◽  
Anthropogenic Activities ◽  
Atmospheric Oxygen ◽  
Regional Scale ◽  
Central Africa ◽  
Heterotrophic Soil Respiration ◽  
Habitable Planet ◽  
Higher Temperature ◽  
Dynamic Description ◽  
The Tropics

Abstract. Atmospheric oxygen (O2) is one of the predominant features that enable Earth as a habitable planet for active and diverse biology. However, observations since the late 1980s indicate that O2 content in the atmosphere is falling steadily at part-per-million level. Although a scientific consensus has emerged that the current decline is generally attributed to the combustion of fossil fuel, a quantitative assessment of the anthropogenic impact on the O2 cycle on both global and regional scale is currently lacking. This paper quantifies the anthropogenic and biological O2 flux over land and provides a quantitative and dynamic description of land O2 budget under impacts of human activities on grid scale. It is found that total anthropogenic O2 flux over land has risen from 35.6 Gt/yr in 2000 to 46.0 Gt/yr in 2013, while the compensation from land (11.5 Gt/yr averaged from 2000 to 2013) displays a faint increase during the same period. High anthropogenic fluxes mainly occur in Eastern Asia, India, North America and Europe caused by fossil fuel combustion and in Central Africa caused by wildfire. Due to strong heterotrophic soil respiration under higher temperature conditions, the positive O2 flux in the tropics is not significant. Instead, boreal forest and Tibetan plateau become the most important sources of atmospheric O2 in the Anthropocene. The anthropogenic oxygen consumption data are publicly available online at https://doi.org/10.1594/PANGAEA.899167.

scholarly journals Prediction of Soil Oxalate Phosphorus using Visible and Near-Infrared Spectroscopy in Natural and Cultivated System Soils of Madagascar

Agriculture ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 177
Author(s):  
Hobimiarantsoa Rakotonindrina ◽  
Kensuke Kawamura ◽  
Yasuhiro Tsujimoto ◽  
Tomohiro Nishigaki ◽  
Herintsitohaina Razakamanarivo ◽  
...  
Keyword(s):  
Prediction Accuracy ◽  
Near Infrared ◽  
Predictive Accuracy ◽  
Regional Scale ◽  
Organic Matter Content ◽  
Partial Least Square ◽  
Least Square ◽  
Near Infrared Reflectance ◽  
Wide Range ◽  
The Tropics

Phosphorus is among the main limiting nutrients for plant growth and productivity in both agricultural and natural ecosystems in the tropics, which are characterized by weathered soil. Soil bioavailable P measurement is necessary to predict the potential growth of plant biomass in these ecosystems. Visible and near-infrared reflectance spectroscopy (Vis-NIRS) is widely used to predict soil chemical and biological parameters as an alternative to time-consuming conventional laboratory analyses. However, quantitative spectroscopic prediction of soil P remains a challenge owing to the difficulty of direct detection of orthophosphate. This study tested the performance of Vis-NIRS with partial least square regression to predict oxalate-extractable P (Pox) content, representing available P for plants in natural (forest and non-forest including fallows and degraded land) and cultivated (upland and flooded rice fields) soils in Madagascar. Model predictive accuracy was assessed based on the coefficient of determination (R2), the root mean squared error of cross-validation (RMSECV), and the residual predictive deviation (RPD). The results demonstrated successful Pox prediction accuracy in natural (n = 74, R² = 0.90, RMSECV = 2.39, and RPD = 3.22), and cultivated systems (n = 142, R² = 0.90, RMSECV = 48.57, and RPD = 3.15) and moderate usefulness at the regional scale incorporating both system types (R² = 0.70, RMSECV = 71.87 and RPD = 1.81). These results were also confirmed with modified bootstrap procedures (N = 10,000 times) using selected wavebands on iterative stepwise elimination–partial least square (ISE–PLS) models. The wavebands relevant to soil organic matter content and Fe content were identified as important components for the prediction of soil Pox. This predictive accuracy for the cultivated system was related to the variability of some samples with high Pox values. However, the use of “pseudo-independent” validation can overestimate the prediction accuracy when applied at site scale suggesting the use of larger and dispersed geographical cover sample sets to build a robust model. Our study offers new opportunities for P quantification in a wide range of ecosystems in the tropics.

Glacial–Interglacial Precipitation Changes

2020 ◽  
Vol 12 (1) ◽  
pp. 525-557 ◽  
Author(s):  
David McGee
Keyword(s):  
Climatic Factors ◽  
Regional Scale ◽  
Precipitation Amount ◽  
Proxy Data ◽  
Precipitation Patterns ◽  
Future Warming ◽  
The Tropics ◽  
Glacial Periods ◽  
Precipitation Changes

Glacial–interglacial cycles have constituted a primary mode of climate variability over the last 2.6 million years of Earth's history. While glacial periods cannot be seen simply as a reverse analogue of future warming, they offer an opportunity to test our understanding of the response of precipitation patterns to a much wider range of conditions than we have been able to directly observe. This review explores key features of precipitation patterns associated with glacial climates, which include drying in large regions of the tropics and wetter conditions in substantial parts of the subtropics and midlatitudes. I describe the evidence for these changes and examine the potential causes of hydrological changes during glacial periods. Central themes that emerge include the importance of atmospheric circulation changes in determining glacial–interglacial precipitation changes at the regional scale, the need to take into account climatic factors beyond local precipitation amount when interpreting proxy data, and the role of glacial conditions in suppressing the strength of Northern Hemisphere monsoon systems.

scholarly journals The Influence of Tropical Deforestation on the Northern Hemisphere Climate by Atmospheric Teleconnections

2010 ◽  
Vol 14 (4) ◽  
pp. 1-34 ◽  
Author(s):  
Peter K. Snyder
Keyword(s):  
Northern Hemisphere ◽  
Land Surface ◽  
Regional Scale ◽  
Storm Track ◽  
Lower Troposphere ◽  
Tropical Deforestation ◽  
Climate Response ◽  
Climate System Model ◽  
Climate Signal ◽  
The Tropics

Abstract Numerous studies have identified the regional-scale climate response to tropical deforestation through changes to water, energy, and momentum fluxes between the land surface and the atmosphere. There has been little research, however, on the role of tropical deforestation on the global climate. Previous studies have focused on the climate response in the extratropics with little analysis of the mechanisms responsible for propagating the signal out of the tropics. A climate modeling study is presented of the physical processes that are important in transmitting a deforestation signal out of the tropics to the Northern Hemisphere extratropics in boreal winter. Using the Community Climate System Model, version 3 Integrated Biosphere Simulator (CCM3–IBIS) climate model and by imposing an exaggerated land surface forcing of complete tropical forest removal, the thermodynamic and dynamical atmospheric response is evaluated regionally within the tropics, globally as the climate signal propagates to the Northern Hemisphere, and then regionally in Eurasia where land–atmosphere feedbacks contribute to amplifying the climate signal and warming the surface and lower troposphere by 1–4 K. Model results indicate that removal of the tropical forests causes weakening of deep tropical convection that excites a Rossby wave train emanating northeastward away from the South American continent. Changes in European storm-track activity cause an intensification and northward shift in the Ferrel cell that leads to anomalous adiabatic warming over a broad region of Eurasia. Regional-scale land–atmosphere feedbacks are found to amplify the warming. While hypothetical, this approach illustrates the atmospheric mechanisms linking the tropics with Eurasia that may otherwise not be detectable with more realistic land-use change simulations.

Changes in future precipitation mean and variability across scales

2020 ◽  
pp. 1-55
Author(s):  
Kevin Schwarzwald ◽  
Andrew Poppick ◽  
Maria Rugenstein ◽  
Jonah Bloch-Johnson ◽  
Jiali Wang ◽  
...  
Keyword(s):  
Regional Scale ◽  
Precipitation Variability ◽  
Climate Projections ◽  
Rainfall Events ◽  
Spatial And Temporal Scales ◽  
Multiplicative Shift ◽  
The Tropics ◽  
Multiplicative Mean ◽  
Small Additive ◽  
Additive Term

AbstractChanges in precipitation variability can have large societal consequences, whether at the short timescales of flash floods or the longer timescales of multi-year droughts. Recent studies have suggested that in future climate projections, precipitation variability rises more steeply than does its mean, leading to concerns about societal impacts. This work evaluates changes in mean precipitation over a broad range of spatial and temporal scales using a range of models from high-resolution regional simulations to millennial-scale global simulations. Results show that changes depend on the scale of aggregation and involve strong regional differences. On local scales that resolve individual rainfall events (hours and tens of kilometers), changes in precipitation distributions are complex and variances rise substantially more than means, as is required given the well-known disproportionate rise in precipitation intensity. On scales that aggregate across many events, distributional changes become simpler and variability changes smaller. At regional scale, future precipitation distributions can be largely reproduced by a simple transformation of present-day precipitation involving a multiplicative shift and a small additive term. The “extra” broadening is negatively correlated with changes in mean precipitation: in strongly “wetting” areas, distributions broaden less than expected from a simple multiplicative mean change; in “drying” areas, distributions narrow less. Precipitation variability changes are therefore of especial concern in the subtropics, which tend to dry under climate change. Outside the tropics, variability changes are similar on timescales from days to decades, i.e. show little frequency dependence. This behavior is highly robust across models, suggesting it may stem from some fundamental constraint.

scholarly journals Hysteresis of tropical forests in the 21st century

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Arie Staal ◽  
Ingo Fetzer ◽  
Lan Wang-Erlandsson ◽  
Joyce H. C. Bosmans ◽  
Stefan C. Dekker ◽  
...  
Keyword(s):  
Climate Change ◽  
Tropical Forests ◽  
Spatial Scales ◽  
Regional Scale ◽  
Climatic Conditions ◽  
Change Scenario ◽  
Amazon Forest ◽  
Recent Climate ◽  
Severe Climate Change ◽  
The Tropics

Abstract Tropical forests modify the conditions they depend on through feedbacks at different spatial scales. These feedbacks shape the hysteresis (history-dependence) of tropical forests, thus controlling their resilience to deforestation and response to climate change. Here, we determine the emergent hysteresis from local-scale tipping points and regional-scale forest-rainfall feedbacks across the tropics under the recent climate and a severe climate-change scenario. By integrating remote sensing, a global hydrological model, and detailed atmospheric moisture tracking simulations, we find that forest-rainfall feedback expands the geographic range of possible forest distributions, especially in the Amazon. The Amazon forest could partially recover from complete deforestation, but may lose that resilience later this century. The Congo forest currently lacks resilience, but is predicted to gain it under climate change, whereas forests in Australasia are resilient under both current and future climates. Our results show how tropical forests shape their own distributions and create the climatic conditions that enable them.

scholarly journals Volcanic eruptions recorded in the Illimani ice core (Bolivia): 1918–1998 and Tambora periods

2003 ◽  
Vol 3 (3) ◽  
pp. 2427-2463 ◽  
Author(s):  
M. De Angelis ◽  
J. Simões ◽  
H. Bonnaveira ◽  
J.-D. Taupin ◽  
R. J. Delmas
Keyword(s):  
Ice Core ◽  
Regional Scale ◽  
Ice Cores ◽  
Volcanic Eruptions ◽  
Global Scale ◽  
Aerosol Composition ◽  
Volcanic Origin ◽  
Tropical Glaciers ◽  
Polar Snow ◽  
The Tropics

Abstract. Acid layers of volcanic origin detected in polar snow and ice layers are commonly used to document past volcanic activity on a global scale or, conversely, to date polar ice cores. Although most cataclysmic eruptions of the last two centuries (Pinatubo, El Chichon, Agung, Krakatoa, Cosiguina, Tambora, etc.) occurred in the tropics, cold tropical glaciers have not been used for the reconstruction of past volcanism. The glaciochemical study of a 137 m ice core drilled in 1999 close to the summit of Nevado Illimani (Eastern Bolivian Andes, 16°37' S, 67°46' W, 6350 m a.s.l.) demonstrates, for the first time, that such eruptions are recorded by both their tropospheric and stratospheric deposits. An 80-year ice sequence (1918–1998) and the Tambora years have been analyzed in detail. In several cases, ash, chloride and fluoride were also detected. The ice records of the Pinatubo (1991), Agung (1963) and Tambora (1815) eruptions are discussed in detail. Less important eruptions located in the Andes are also recorded and may also disturb background aerosol composition on a regional scale.

scholarly journals Hysteresis of tropical forests in the 21st century

2020 ◽  
Author(s):  
Arie Staal ◽  
Ingo Fetzer ◽  
Lan Wang-Erlandsson ◽  
Joyce Bosmans ◽  
Stefan Dekker ◽  
...  
Keyword(s):  
Climate Change ◽  
Tropical Forests ◽  
Spatial Scales ◽  
Regional Scale ◽  
Climatic Conditions ◽  
Change Scenario ◽  
Amazon Forest ◽  
Recent Climate ◽  
Severe Climate Change ◽  
The Tropics

<p>Tropical forests modify the conditions they depend on through feedbacks on different spatial scales. These feedbacks shape the hysteresis (history-dependence) of tropical forests, thus controlling their resilience to deforestation and response to climate change. Here we present the emergent hysteresis from local-scale tipping points and regional-scale forest-rainfall feedbacks across the tropics under the recent climate and a severe climate-change scenario. By integrating remote sensing, a global hydrological model, and detailed atmospheric moisture tracking simulations, we find that forest-rainfall feedback expands the range of possible forest distributions especially in the Amazon. The Amazon forest could partially recover from complete deforestation, but may lose that resilience later this century. The Congo forest lacks resilience, but gains it under climate change, whereas forests in Australasia are resilient under both current and future climates. Our results show how tropical forests shape their own distributions and create the climatic conditions that enable them.</p>

scholarly journals Regional N<sub>2</sub>O fluxes in Amazonia derived from aircraft vertical profiles

2009 ◽  
Vol 9 (4) ◽  
pp. 17429-17463 ◽  
Author(s):  
M. T. S. D'Amelio ◽  
L. V. Gatti ◽  
J. B. Miller ◽  
P. Tans
Keyword(s):  
Biomass Burning ◽  
Regional Scale ◽  
Dry Season ◽  
N2o Emissions ◽  
Amazon Forest ◽  
Vertical Profiles ◽  
Wet Season ◽  
N2o Flux ◽  
New Approach ◽  
The Tropics

Abstract. Nitrous oxide (N2O) is the third most important anthropogenic greenhouse gas. Globally, the main sources of N2O are nitrification and denitrification in soils. About two thirds of the soil emissions occur in the tropics and approximately 20% originate in wet rainforest ecosystems, like the Amazon forest. The work presented here involves aircraft vertical profiles of N2O from the surface to 4 km over two sites in the Eastern and Central Amazon: Tapajós National Forest (SAN) and Cuieiras Biologic Reserve (MAN), and the estimation of N2O fluxes for regions upwind of these sites. To our knowledge, these regional scale N2O measurements in Amazonia are unique and represent a new approach to looking regional scale emissions. The fluxes upwind of MAN exhibited little seasonality, and the annual mean was 2.1±1.0 mg N2O m−2 day−1, higher than that for fluxes upwind of SAN, which averaged 1.5±1.6 mg N2O m−2 day−1. The higher rainfall around the MAN site could explain the higher N2O emissions. For fluxes from the coast to SAN seasonality is present for all years, with high fluxes in the months of March through May, and in November through December. The first peak of N2O flux is strongly associated with the wet season. The second peak of high N2O flux recorded at SAN occurs during the dry season and can not be easily explained. However, about half of the dry season profiles exhibit significant correlations with CO, indicating a larger than expected source of N2O from biomass burning. The average CO:N2O ratio for all profiles sampled during the dry season is 94±77 mol CO:mol N2O and suggests a larger biomass burning contribution to the global N2O budget than previously reported.

scholarly journals Regional N<sub>2</sub>O fluxes in Amazonia derived from aircraft vertical profiles

2009 ◽  
Vol 9 (22) ◽  
pp. 8785-8797 ◽  
Author(s):  
M. T. S. D'Amelio ◽  
L. V. Gatti ◽  
J. B. Miller ◽  
P. Tans
Keyword(s):  
Biomass Burning ◽  
Regional Scale ◽  
Dry Season ◽  
N2o Emissions ◽  
Amazon Forest ◽  
Vertical Profiles ◽  
Wet Season ◽  
N2o Flux ◽  
Nitrification And Denitrification ◽  
The Tropics

Abstract. Nitrous oxide (N2O) is the third most important anthropogenic greenhouse gas. Globally, the main sources of N2O are nitrification and denitrification in soils. About two thirds of the soil emissions occur in the tropics and approximately 20% originate in wet rainforest ecosystems, like the Amazon forest. The work presented here involves aircraft vertical profiles of N2O from the surface to 4 km over two sites in the Eastern and Central Amazon: Tapajós National Forest (SAN) and Cuieiras Biologic Reserve (MAN), and the estimation of N2O fluxes for regions upwind of these sites. To our knowledge, these regional scale N2O measurements in Amazonia are unique and represent a new approach to looking regional scale emissions. The fluxes upwind of MAN exhibited little seasonality, and the annual mean was 2.1±1.0 mg N2O m−2 day−1, higher than that for fluxes upwind of SAN, which averaged 1.5±1.6 mg N2O m−2 day−1. The higher rainfall around the MAN site could explain the higher N2O emissions, as a result of increased soil moisture accelerating microbial nitrification and denitrification processes. For fluxes from the coast to SAN seasonality is present for all years, with high fluxes in the months of March through May, and in November through December. The first peak of N2O flux is strongly associated with the wet season. The second peak of high N2O flux recorded at SAN occurs during the dry season and can not be easily explained. However, about half of the dry season profiles exhibit significant correlations with CO, indicating a larger than expected source of N2O from biomass burning. The average CO:N2O ratio for all profiles sampled during the dry season is 94±77 mol CO:mol N2O and suggests a larger biomass burning contribution to the global N2O budget than previously reported.

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