Asymmetric warming significantly affects net primary production, but not ecosystem carbon balances of forest and grassland ecosystems in northern China

We combine the process-based ecosystem model (Biome-BGC) with climate change-scenarios based on both RegCM3 model outputs and historic observed trends to quantify differential effects of symmetric and asymmetric warming on ecosystem net primary productivity (NPP), heterotrophic respiration (Rh) and net ecosystem productivity (NEP) of six ecosystem types representing different climatic zones of northern China. Analysis of covariance shows that NPP is significant greater at most ecosystems under the various environmental change scenarios once temperature asymmetries are taken into consideration. However, these differences do not lead to significant differences in NEP, which indicates that asymmetry in climate change does not result in significant alterations of the overall carbon balance in the dominating forest or grassland ecosystems. Overall, NPP, Rh and NEP are regulated by highly interrelated effects of increases in temperature and atmospheric CO2 concentrations and precipitation changes, while the magnitude of these effects strongly varies across the six sites. Further studies underpinned by suitable experiments are nonetheless required to further improve the performance of ecosystem models and confirm the validity of these model predictions. This is crucial for a sound understanding of the mechanisms controlling the variability in asymmetric warming effects on ecosystem structure and functioning

Increasing Summer Night Temperatures during a 24-Year Periods in Japan:Implications for Rice Production

Summer night temperatures are increasing across most of the globe. In this study, we attempted to detect variability in recent increasing trends in summer night temperatures in Japan. Hourly night temperatures higher than 25°C and 30°C measured by the Automated Meteorological Data Acquisition System (AMeDAS) of the Japan Meteorological Agency were accumulated for each night during each of six approximately 10 day periods during July and August from 1979 to 2002. These two parameters, called ANT25 and ANT30,were used for our analyses. Although increasing trends in night temperature were conspicuous in large cities such as Tokyo, Osaka, and Nagoya, they were also observed widely throughout Japan, including small cities and rural areas. The highest rates of increase in ANT25 were found in early August from Kanto and Hokuriku districts and to the west along the coast. The effects of night warming on rice production in Japan are discusse

Live fast, die young? Day- and night-warming affect the growth, survivorship, and behavior of caterpillars in the field.

While both daytime and nighttime temperatures are increasing with climate change, few studies have experimentally investigated their differential effects under field conditions. We conducted a factorial field experiment examining how day- and night-warming impact the growth, survivorship, and behavior of cabbage white caterpillars (Pieris rapae). In this experiment, the night-warming only treatment showed the highest rates of caterpillar growth, but also showed the highest mortality, the shortest maximum caterpillar lengths, the least accumulated herbivory, and reduced pupation. Caterpillars in the treatments that were not warmed during the day showed daytime-shifted growth, and caterpillars in the combined day- and night-warming treatment showed strongly night-shifted herbivory. Both biotic (e.g., predation risk) and abiotic (e.g., thermal) factors could have contributed to these results. Broadly, these results show the importance of temperature-mediated behavioral changes in diel activity for caterpillar development and survival. These results also support the emerging hypotheses that periods of reduced activity may be important for successful development, that warmer nighttime conditions could limit a temporal thermal refuge for caterpillars, and that increasing temperatures could increase the likelihood of metabolic meltdown. This experiment also illustrates the value of field studies to provide insights into how ectotherms might respond to ongoing climate change

Microclimate Data Improve Predictions of Insect Abundance Models Based on Calibrated Spatiotemporal Temperatures

International audienceSpecialty section: This article was submitted to Invertebrate Physiology, a section of the journal Frontiers in Physiology A large body of literature has recently recognized the role of microclimates in controlling the physiology and ecology of species, yet the relevance of fine-scale climatic data for modeling species performance and distribution remains a matter of debate. Using a 6-year monitoring of three potato moth species, major crop pests in the tropical Andes, we asked whether the spatiotemporal resolution of temperature data affect the predictions of models of moth performance and distribution. For this, we used three different climatic data sets: (i) the WorldClim dataset (global dataset), (ii) air temperature recorded using data loggers (weather station dataset), and (iii) air crop canopy temperature (microclimate dataset). We developed a statistical procedure to calibrate all datasets to monthly and yearly variation in temperatures, while keeping both spatial and temporal variances (air monthly temperature at 1 km² for the WorldClim dataset, air hourly temperature for the weather station, and air minute temperature over 250 m radius disks for the microclimate dataset). Then, we computed pest performances based on these three datasets. Results for temperature ranging from 9 to 11 • C revealed discrepancies in the simulation outputs in both survival and development rates depending on the spatiotemporal resolution of the temperature dataset. Temperature and simulated pest performances were then combined into multiple linear regression models to compare predicted vs. field data. We used an additional set of study sites to test the ability of the results of our model to be extrapolated over larger scales. Results showed that the model implemented with microclimatic data best predicted observed pest abundances for our study sites, but was less accurate than the global dataset model when performed at larger scales. Our simulations therefore stress the importance to consider different temperature datasets depending on the issue to be solved in order to accurately predict species abundances. In conclusion, keeping in mind that the mismatch between the size of organisms and the scale at which climate data are collected and modeled remains a key issue, temperature dataset selection should be balanced by the desired output spatiotemporal scale for better predicting pest dynamics and developing efficient pest management strategies

The Mars Global Dust Storm of 2018

Mars is a dusty planet. Wind often lifts dust from the surface into the air forming clouds of dust at different locations across Mars. These dust storms typically last up to a couple days and grow to a few hundred km in size. However, once in a long while when conditions are just right, localized dust storms can interact in a way that optically thick suspended dust covers nearly the entire planet remaining aloft for weeks to months. These global-scale dust storms are the most dramatic of all weather phenomena on Mars, greatly altering the thermal structure and dynamics of the Martian atmosphere and significantly changing the global distribution of surface dust. Such a global-scale dust storm occurred during the summer of 2018, the first such event since 2007. The global dust storm was observed by an international fleet of spacecraft in Mars orbit and on the surface of Mars providing an unprecedented view of the initiation, growth, and decay of the storm as well as the physical properties of the dust during the storm's evolution. The 2018 global-scale dust storm was observed to grow from several localized dust-lifting centers with wind-blown dust suspended in the atmosphere encircling Mars after about two weeks of activity. Dust column optical depths recorded by the Opportunity and Curiosity rovers on the surface were the highest ever recorded on Mars. Peak global intensity of the dust storm was reached in early July 2018. Over the next couple months, the dust settled out and the atmosphere returned to its climatological average. Only a small number of global-scale dust storms have been observed on Mars, and so detailed analysis of the observations of this storm will provide important new insight into how these events occur and their effect on the current Mars climate