scholarly journals Long-term thermal sensitivity of Earth’s tropical forests

Science ◽  
2020 ◽  
Vol 368 (6493) ◽  
pp. 869-874 ◽  
Author(s):  
Martin J. P. Sullivan ◽  
Simon L. Lewis ◽  
Kofi Affum-Baffoe ◽  
Carolina Castilho ◽  
Flávia Costa ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Climate Adaptation ◽  
Global Climate ◽  
Thermal Sensitivity ◽  
Forest Carbon ◽  
Maximum Temperature ◽  
Permanent Plots ◽  
Short Term ◽  
Earth’S Climate

The sensitivity of tropical forest carbon to climate is a key uncertainty in predicting global climate change. Although short-term drying and warming are known to affect forests, it is unknown if such effects translate into long-term responses. Here, we analyze 590 permanent plots measured across the tropics to derive the equilibrium climate controls on forest carbon. Maximum temperature is the most important predictor of aboveground biomass (−9.1 megagrams of carbon per hectare per degree Celsius), primarily by reducing woody productivity, and has a greater impact per °C in the hottest forests (>32.2°C). Our results nevertheless reveal greater thermal resilience than observations of short-term variation imply. To realize the long-term climate adaptation potential of tropical forests requires both protecting them and stabilizing Earth’s climate.

scholarly journals Resistance to thermal stress in corals without changes in symbiont composition

2011 ◽  
Vol 279 (1731) ◽  
pp. 1100-1107 ◽  
Author(s):  
Anthony J. Bellantuono ◽  
Ove Hoegh-Guldberg ◽  
Mauricio Rodriguez-Lanetty
Keyword(s):  
Climate Change ◽  
Thermal Stress ◽  
Coral Reefs ◽  
Global Climate Change ◽  
Global Climate ◽  
Thermal Sensitivity ◽  
Physiological Plasticity ◽  
Short Term ◽  
Genotypic Analysis

Discovering how corals can adjust their thermal sensitivity in the context of global climate change is important in understanding the long-term persistence of coral reefs. In this study, we showed that short-term preconditioning to higher temperatures, 3°C below the experimentally determined bleaching threshold, for a period of 10 days provides thermal tolerance for the symbiosis stability between the scleractinian coral, Acropora millepora and Symbiodinium . Based on genotypic analysis, our results indicate that the acclimatization of this coral species to thermal stress does not come down to simple changes in Symbiodinium and/or the bacterial communities that associate with reef-building corals. This suggests that the physiological plasticity of the host and/or symbiotic components appears to play an important role in responding to ocean warming. The further study of host and symbiont physiology, both of Symbiodinium and prokaryotes, is of paramount importance in the context of global climate change, as mechanisms for rapid holobiont acclimatization will become increasingly important to the long-standing persistence of coral reefs.

scholarly journals Analytical Determination of the Brake Temperature Mode During Repetitive Short-Term Braking

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1912
Author(s):  
Aleksander Yevtushenko ◽  
Katarzyna Topczewska ◽  
Michal Kuciej
Keyword(s):  
Friction Pair ◽  
Thermal Sensitivity ◽  
Finite Difference Methods ◽  
Temporal Variations ◽  
Frictional Heat ◽  
Maximum Temperature ◽  
Analytical Determination ◽  
Flash Temperature ◽  
Short Term ◽  
The One

An algorithm to determine the maximum temperature of brake systems during repetitive short-term (RST) braking mode has been proposed. For this purpose, the intermittent mode of braking was given in the form of a few cyclic stages consisting of subsequent braking and acceleration processes. Based on the Chichinadze’s hypothesis of temperature summation, the evolutions of the maximum temperature during each cycle were calculated as the sum of the mean temperature on the nominal contact surface of the friction pair elements and temperature attained on the real contact areas (flash temperature). In order to find the first component, the analytical solution to the one-dimensional thermal problem of friction for two semi-spaces taking into account frictional heat generation was adapted. To find the flash temperature, the solution to the problem for the semi-infinite rod sliding with variable velocity against a smooth surface was used. In both solutions, the temperature-dependent coefficient of friction and thermal sensitivity of materials were taken into account. Numerical calculations were carried out for disc and drum brake systems. The obtained temporal variations of sliding velocity, friction power and temperature were investigated on each stage of braking. It was found that the obtained results agree well with the corresponding data established by finite element and finite-difference methods.

Introduction

2004 ◽  
Author(s):  
Robert A. Berner
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Carbon Cycle ◽  
Global Climate ◽  
Geological Time ◽  
Short Term ◽  
Quaternary Period ◽  
Geological Time Scale ◽  
The Earth

The cycle of carbon is essential to the maintenance of life, to climate, and to the composition of the atmosphere and oceans. What is normally thought of as the “carbon cycle” is the transfer of carbon between the atmosphere, the oceans, and life. This is not the subject of interest of this book. To understand this apparently confusing statement, it is necessary to separate the carbon cycle into two cycles: the short-term cycle and the long-term cycle. The “carbon cycle,” as most people understand it, is represented in figure 1.1. Carbon dioxide is taken up via photosynthesis by green plants on the continents or phytoplankton in the ocean. On land carbon is transferred to soils by the dropping of leaves, root growth, and respiration, the death of plants, and the development of soil biota. Land herbivores eat the plants, and carnivores eat the herbivores. In the oceans the phytoplankton are eaten by zooplankton that are in turn eaten by larger and larger organisms. The plants, plankton, and animals respire CO2. Upon death the plants and animals are decomposed by microorganisms with the ultimate production of CO2. Carbon dioxide is exchanged between the oceans and atmosphere, and dissolved organic matter is carried in solution by rivers from soils to the sea. This all constitutes the shortterm carbon cycle. The word “short-term” is used because the characteristic times for transferring carbon between reservoirs range from days to tens of thousands of years. Because the earth is more than four billion years old, this is short on a geological time scale. As the short-term cycle proceeds, concentrations of the two principal atmospheric gases, CO2 and CH4, can change as a result of perturbations of the cycle. Because these two are both greenhouse gases—in other words, they adsorb outgoing infrared radiation from the earth surface—changes in their concentrations can involve global warming and cooling over centuries and many millennia. Such changes have accompanied global climate change over the Quaternary period (past 2 million years), although other factors, such as variations in the receipt of solar radiation due to changes in characteristics of the earth’s orbit, have also contributed to climate change.

scholarly journals The carbon sink of tropical seasonal forests in southeastern Brazil can be under threat

2020 ◽  
Vol 6 (51) ◽  
pp. eabd4548
Author(s):  
Vinícius Andrade Maia ◽  
Alisson Borges Miranda Santos ◽  
Natália de Aguiar-Campos ◽  
Cléber Rodrigo de Souza ◽  
Matheus Coutinho Freitas de Oliveira ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Carbon Sink ◽  
Global Climate ◽  
Carbon Sources ◽  
Southeastern Brazil ◽  
Forest Sites ◽  
Tropical Seasonal Forest ◽  
Terrestrial Carbon Sink ◽  
Seasonal Forests

Tropical forests have played an important role as a carbon sink over time. However, the carbon dynamics of Brazilian non-Amazon tropical forests are still not well understood. Here, we used data from 32 tropical seasonal forest sites, monitored from 1987 to 2020 (mean site monitoring length, ~15 years) to investigate their long-term trends in carbon stocks and sinks. Our results highlight a long-term decline in the net carbon sink (0.13 Mg C ha−1 year−1) caused by decreasing carbon gains (2.6% by year) and increasing carbon losses (3.4% by year). The driest and warmest sites are experiencing the most severe carbon sink decline and have already moved from carbon sinks to carbon sources. Because of the importance of the terrestrial carbon sink for the global climate, policies are needed to mitigate the emission of greenhouse gases and to restore and protect tropical seasonal forests.

scholarly journals Dynamic modelling of cold-hardiness in tea buds by imitating past temperature memory

2020 ◽  
Author(s):  
Kensuke Kimura ◽  
Daisuke Yasutake ◽  
Takahiro Oki ◽  
Koichiro Yoshida ◽  
Masaharu Kitano
Keyword(s):  
Cold Stress ◽  
Cold Acclimation ◽  
Dynamic Model ◽  
Cold Hardiness ◽  
Global Climate ◽  
Effective Means ◽  
Dynamic Modelling ◽  
Short Term ◽  
Mean Square Errors

Abstract Background and Aims Most perennial plants memorize cold stress for a certain period and retrieve the memories for cold acclimation and deacclimation, which leads to seasonal changes in cold-hardiness. Therefore, a model for evaluating cold stress memories is required for predicting cold-hardiness and for future frost risk assessments under warming climates. In this study we develop a new dynamic model of cold-hardiness by introducing a function imitating past temperature memory in the processes of cold acclimation and deacclimation. Methods We formulated the past temperature memory for plants using thermal time weighted by a forgetting function, and thereby proposed a dynamic model of cold-hardiness. We used the buds of tea plants (Camellia sinensis) from two cultivars, ‘Yabukita’ and ‘Yutakamidori’, to calibrate and validate this model based on 10 years of observed cold-hardiness data. Key Results The model captured more than 90 % of the observed variation in cold-hardiness and predicted accurate values for both cultivars, with root mean square errors of ~1.0 °C. The optimized forgetting function indicated that the tea buds memorized both short-term (recent days) and long-term (previous months) temperatures. The memories can drive short-term processes such as increasing/decreasing the content of carbohydrates, proteins and antioxidants in the buds, as well as long-term processes such as determining the bud phenological stage, both of which vary with cold-hardiness. Conclusions The use of a forgetting function is an effective means of understanding temperature memories in plants and will aid in developing reliable predictions of cold-hardiness for various plant species under global climate warming.

Comparison of Short-Term and Long-Term Radiative Feedbacks and Variability in Twentieth-Century Global Climate Model Simulations

2013 ◽  
Vol 26 (24) ◽  
pp. 10051-10070 ◽  
Author(s):  
Meghan M. Dalton ◽  
Karen M. Shell
Keyword(s):  
Twentieth Century ◽  
Water Vapor ◽  
Climate Sensitivity ◽  
Surface Albedo ◽  
Global Climate ◽  
Global Climate Model ◽  
Atmospheric Temperature ◽  
Global Climate Models ◽  
Short Term

Abstract The climate sensitivity uncertainty of global climate models (GCMs) is partly due to the spread of individual feedbacks. One approach to constrain long-term climate sensitivity is to use the relatively short observational record, assuming there exists some relationship in feedbacks between short and long records. The present work tests this assumption by regressing short-term feedback metrics, characterized by the 20-yr feedback as well as interannual and intra-annual metrics, against long-term longwave water vapor, longwave atmospheric temperature, and shortwave surface albedo feedbacks calculated from 13 twentieth-century GCM simulations. Estimates of long-term feedbacks derived from reanalysis observations and statistically significant regressions are consistent with but no more constrained than earlier estimates. For the interannual metric, natural variability contributes to the feedback uncertainty, reducing the ability to estimate the interannual behavior from one 20-yr time slice. For both the interannual and intra-annual metrics, uncertainty in the intermodel relationships between 20-yr metrics and 100-yr feedbacks also contributes to the feedback uncertainty. Because of differences in time scales of feedback processes, relationships between the 20-yr interannual metric and 100-yr water vapor and atmospheric temperature feedbacks are significant for only one feedback calculation method. The intra-annual and surface albedo relationships show more complex behavior, though positive correspondence between Northern Hemisphere surface albedo intra-annual metrics and 100-yr feedbacks is consistent with previous studies. Many relationships between 20-yr metrics and 100-yr feedbacks are sensitive to the specific GCMs included, highlighting that care should be taken when inferring long-term feedbacks from short-term observations.

scholarly journals A Multivariate Multi-Step LSTM Forecasting Model For Tuberculosis Incidence With Model Explanation In Liaoning Province, China

2022 ◽  
Author(s):  
Enbin Yang ◽  
Hao Zhang ◽  
Xinsheng Guo ◽  
Zinan Zang ◽  
Zhen Liu ◽  
...  
Keyword(s):  
Short Term Memory ◽  
Arima Model ◽  
Mean Absolute Percentage Error ◽  
Liaoning Province ◽  
Maximum Temperature ◽  
Percentage Error ◽  
Short Term ◽  
Forecasting Models ◽  
Absolute Percentage Error

Abstract Background: In addition to COVID-19, tuberculosis (TB) is the respiratory infectious disease with the highest incidence in China. We aim to design a series of forecasting models and find the factors that affect the incidence of TB, thereby improving the accuracy of the incidence prediction. Results: In this paper, we developed a new interpretable prediction system based on the multivariate multi-step Long Short-Term Memory (LSTM) model and SHapley Additive exPlanation (SHAP) method. Moreover, four accuracy measures are introduced into the system: Root Mean Square Error, Mean Absolute Error, Mean Absolute Percentage Error, and symmetric Mean Absolute Percentage Error. Meanwhile, the Autoregressive Integrated Moving Average (ARIMA) model and seasonal ARIMA model are established. The multi-step ARIMA-LSTM model is proposed for the first time to examine the performance of each model in the short, medium, and long term, respectively. Compared with the ARIMA model, each error of the multivariate 2-step LSTM model is reduced by 12.92%, 15.94%, 15.97%, and 14.81% in the short term. The 3-step ARIMA-LSTM model achieved excellent performance, with each error decreased to 15.19%, 33.14%, 36.79%, and 29.76% in the medium and long term. We provide the local and global explanation of the multivariate single-step LSTM model in the field of incidence prediction, pioneering. Conclusions: The multivariate 2-step LSTM model is suitable for short-term forecasts, and the 3-step ARIMA-LSTM model is appropriate for medium and long-term forecasts. In addition, the prediction effect was better than similar TB incidence forecasting models. The SHAP results indicate that the five most crucial features are maximum temperature, average relative humidity, local financial budget, monthly sunshine percentage, and sunshine hours.

Fifty years of Marine and Freshwater Research

1999 ◽  
Keyword(s):  
Coral Reefs ◽  
Sea Level ◽  
Climate Changes ◽  
Sea Water ◽  
Global Climate ◽  
Short Term ◽  
Natural Factors ◽  
Carbon Dioxide Concentrations ◽  
Minimal Damage

Factors causing global degradation of coral reefs are examined briefly as a basis for predicting the likely consequences of increases in these factors. The earlier consensus was that widespread but localized damage from natural factors such as storms, and direct anthropogenic effects such as increased sedimentation, pollution and exploitation, posed the largest immediate threat to coral reefs. Now truly global factors associated with accelerating Global Climate Change are either damaging coral reefs or have the potential to inflict greater damage in the immediate future: e.g. increases in coral bleaching and mortality, and reductions in coral calcification due to changes in sea-water chemistry with increasing carbon dioxide concentrations. Rises in sea level will probably disrupt human communities and their cultures by making coral cays uninhabitable, whereas coral reefs will sustain minimal damage from the rise in sea level. The short-term (decades) prognosis is indeed grim, with major reductions almost certain in the extent and biodiversity of coral reefs, and severe disruptions to cultures and economies dependent on reef resources. The long-term (centuries to millennia) prognosis is more encouraging because coral reefs have remarkable resilience to severe disruption and will probably show this resilience in the future when climate changes either stabilize or reverse.

scholarly journals We Are All in the Same Boat

2021 ◽  
Vol 20 (13) ◽  
Author(s):  
Alan Feng ◽  
Haishi Li
Keyword(s):  
International Trade ◽  
Climate Adaptation ◽  
Global Climate ◽  
Asset Price ◽  
Climate Risks ◽  
Positive Externalities ◽  
Climate Change Risks ◽  
Stock Market Valuation ◽  
Trade Partner

Are assets in a landlocked country subject to sea-level rise risk? In this paper, we study the cross-border spillovers of physical climate risks through international trade and supply chain linkages. As we base our findings on historical data between 1970 and 2018, we observe that globalization increased the similarity of countries’ global climate risk exposures. Exposures to foreign climatic disasters in major trade partner countries (both upstream and downstream) lower the home-country stock market valuation for the aggregate market and for the tradable sectors. We also find that exposures to foreign long-term climate change risks reduce the asset price valuations of the tradable sectors at home. Findings in this paper suggest that climate adaptation efforts in a country can have positive externalities on other countries’ macrofinancial performance and stability through international trade.

scholarly journals The CALIPSO Mission

2010 ◽  
Vol 91 (9) ◽  
pp. 1211-1230 ◽  
Author(s):  
D. M. Winker ◽  
J. Pelon ◽  
J. A. Coakley ◽  
S. A. Ackerman ◽  
R. J. Charlson ◽  
...  
Keyword(s):  
Global Climate ◽  
Radiation Budget ◽  
Atmospheric Measurements ◽  
Joint Project ◽  
Space Agency ◽  
Early Results ◽  
Infrared Spectral ◽  
Passive Sensors ◽  
Earth’S Climate

Aerosols and clouds have important effects on Earth's climate through their effects on the radiation budget and the cycling of water between the atmosphere and Earth's surface. Limitations in our understanding of the global distribution and properties of aerosols and clouds are partly responsible for the current uncertainties in modeling the global climate system and predicting climate change. The CALIPSO satellite was developed as a joint project between NASA and the French space agency CNES to provide needed capabilities to observe aerosols and clouds from space. CALIPSO carries CALIOP, a two-wavelength, polarization-sensitive lidar, along with two passive sensors operating in the visible and thermal infrared spectral regions. CALIOP is the first lidar to provide long-term atmospheric measurements from Earth's orbit. Its profiling and polarization capabilities offer unique measurement capabilities. Launched together with the CloudSat satellite in April 2006 and now flying in formation with the A-train satellite constellation, CALIPSO is now providing information on the distribution and properties of aerosols and clouds, which is fundamental to advancing our understanding and prediction of climate. This paper provides an overview of the CALIPSO mission and instruments, the data produced, and early results.

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