Land Use Effects on Climate: Current State, Recent Progress, and Emerging Topics

Purpose of Review As demand for food and fiber, but also for negative emissions, brings most of the Earth’s land surface under management, we aim to consolidate the scientific progress of recent years on the climatic effects of global land use change, including land management, and related land cover changes (LULCC). Recent Findings We review the methodological advances in both modeling and observations to capture biogeochemical and biogeophysical LULCC effects and summarize the knowledge on underlying mechanisms and on the strength of their effects. Recent studies have raised or resolved several important questions related to LULCC: How can we derive CO2 fluxes related to LULCC from satellites? Why are uncertainties in LULCC-related GHG fluxes so large? How can we explain that estimates of afforestation/reforestation potentials diverge by an order of magnitude? Can we reconcile the seemingly contradicting results of models and observations concerning the cooling effect of high-latitude deforestation? Summary Major progress has been achieved in understanding the complementarity of modeling, observations, and inventories for estimating the impacts of various LULCC practices on carbon, energy, and water fluxes. Emerging fields are the operationalization of the recently achieved integration of approaches, such as a full greenhouse gas balance of LULCC, mapping of emissions from global models to country-reported emissions data, or model evaluation against local biogeophysical observations. Fundamental challenges remain, however, e.g., in separating anthropogenic from natural land use dynamics and accurately quantifying the first. Recent progress has laid the foundation for future research to integrate the local to global scales at which the various effects act, to create co-benefits between global mitigation, including land-based carbon dioxide removal, and changes in local climate for effective adaptation strategies.

The Effect of Using a New Parameterization of Nucleation in the WRF-Chem Model on New Particle Formation in a Passive Volcanic Plume

We investigated the role of the passive volcanic plume of Mount Etna (Italy) in the formation of new particles in the size range of 2.5–10 nm through the gas-to-particle nucleation of sulfuric acid (H2SO4) precursors, formed from the oxidation of SO2, and their evolution to particles with diameters larger than 100 nm. Two simulations were performed using the Weather Research and Forecasting Model coupled with chemistry (WRF-Chem) under the same configuration, except for the nucleation parameterization implemented in the model: the activation nucleation parameterization (JS1 = 2.0 × 10−6 × (H2SO4)) in the first simulation (S1) and a new parameterization for nucleation (NPN) (JS2 = 1.844 × 10−8 × (H2SO4)1.12) in the second simulation (S2). The comparison of the numerical results with the observations shows that, on average, NPN improves the performance of the model in the prediction of the H2SO4 concentrations, newly-formed particles (~2.5–10 nm), and their growth into larger particles (10–100 nm) by decreasing the rates of H2SO4 consumption and nucleation relative to S1. In addition, particles formed in the plume do not grow into cloud condensation nuclei (CCN) sizes (100–215 nm) within a few hours of the vent (tens of km). However, tracking the size evolution of simulated particles along the passive plume indicates the downwind formation of particles larger than 100 nm more than 100 km far from the vent with relatively high concentrations relative to the background (more than 1500 cm−3) in S2. These particles, originating in the volcanic source, could affect the chemical and microphysical properties of clouds and exert regional climatic effects over time.

Blue and green food webs respond differently to elevation and land use

While aquatic (blue) and terrestrial (green) food webs are parts of the same landscape, it remains unclear whether they respond similarly to shared environmental gradients. We use empirical community data from hundreds of sites across Switzerland, and show that blue and green food webs have different structural and ecological properties along elevation as a temperature proxy, and among various land-use types. Specifically, in green food webs, their modular structure increases with elevation and the overlap of consumers' diet niche decreases, while the opposite pattern is observed in blue food webs. Such differences between blue and green food webs are particularly pronounced in farmland-dominated habitats, indicating that anthropogenic habitat modification moderates the climatic effects on food webs but differently in blue versus green systems. These findings indicate general structural differences between blue and green food webs and suggest their potential divergent future alterations through land use or climatic changes.

Solar radiation characteristics at Qena / Egypt

Measurements of the hourly global solar radiation (G) and its diffuse component (D) on a horizontal surface have been carried out in Qena / Upper Egypt in the period from June 1992 to May 1993. The corresponding diffuse fraction (DIG) is calculated. Diurnal variations of the results have been studied. Also the daily totals values and its monthly and seasonal averages as well as their frequency distributions were computed and examined. The seasonal and climatic effects on the fluctuation of the results are discussed. These effects were particularly large during spring and Winter months owing to the high fluctuation of the atmospheric conditions with aspect to amount of clouds, water content, and concentration of aerosol dust particles. The influence of clouds is also considered. It shows small effect on the results (4.5%), reflecting the low degree of cloudiness in the study region. The relation between the diffuse fraction and clearness index (G/Go) shows that most of the points lies in the region of the high availability of the incoming solar radiation. In general the study shows clearly the abundance of solar energy in Qena / Egypt, and the suitability of its climate for using it in different applications.

Bayesian spatio-temporal distributed lag modeling for delayed climatic effects on sparse malaria incidence data

Background In many areas of the Greater Mekong Subregion (GMS), malaria endemic regions have shrunk to patches of predominantly low-transmission. With a regional goal of elimination by 2030, it is important to use appropriate methods to analyze and predict trends in incidence in these remaining transmission foci to inform planning efforts. Climatic variables have been associated with malaria incidence to varying degrees across the globe but the relationship is less clear in the GMS and standard methodologies may not be appropriate to account for the lag between climate and incidence and for locations with low numbers of cases. Methods In this study, a methodology was developed to estimate the spatio-temporal lag effect of climatic factors on malaria incidence in Thailand within a Bayesian framework. A simulation was conducted based on ground truth of lagged effect curves representing the delayed relation with sparse malaria cases as seen in our study population. A case study to estimate the delayed effect of environmental variables was used with malaria incidence at a fine geographic scale of sub-districts in a western province of Thailand. Results From the simulation study, the model assumptions which accommodated both delayed effects and excessive zeros appeared to have the best overall performance across evaluation metrics and scenarios. The case study demonstrated lagged climatic effect estimation of the proposed modeling with real data. The models appeared to be useful to estimate the shape of association with malaria incidence. Conclusions A new method to estimate the spatiotemporal effect of climate on malaria trends in low transmission settings is presented. The developed methodology has potential to improve understanding and estimation of past and future trends in malaria incidence. With further development, this could assist policy makers with decisions on how to more effectively distribute resources and plan strategies for malaria elimination.

Analysis of Indian Traditional Buildings using Passive Cooling through Natural Ventilation Techniques

There is a rapid increase in the use of active cooling strategies for ventilation and air circulation in the recent scenario, and hence an urge of climate-responsive buildings is a need of today. Taking the advantage of local climate and designing buildings that decrease energy use can be achieved by implementing passive cooling strategies in a building. The present study focuses on how various solar passive techniques have helped in designing climate-responsive structures in the past and how its implementation can enhance the structure in modern construction techniques. By analysing structures from the past and studying the science behind them, the passive cooling effect and its development in design implementation can be examined. The paper concludes by having incited on how solar passive strategies can help to create a flexible building, responding to climatic effects and its evolution over a period of time. Keywords: Climate responsive, Hot-dry climate, passive cooling, Traditional buildings

Urban Expansion and Rising Surface Temperature: A Multi Temporal Assessment in Kochi Metropolis, Kerala

The process of urbanization and urban growth has resulted in rapid, uncontrolled conversion of natural land cover and spreading of impervious concrete surfaces in many parts of the world leading to serious environmental concerns. There are a myriad of micro climatic effects due to urban growth. One of the significant consequences is the rising urban temperature. Urban surface temperature responds to changes in land use/land cover dynamics and urban expansion. This would ultimately lead to local climatic changes and would accentuate global warming. Geo spatial technology provides sophisticated tools for analyzing urban features and micro climates. Land surface temperature (LST) or the radiant energy from earth surface can be calculated using thermal bands of satellite data. Kochi, the largest urban agglomeration in Kerala, is undergoing hasty developments and land modifications. This study attempts to monitor changes in land surface temperature from 2000 to 2020 along with changes in built up and vegetation cover. The results revealed that the average surface temperature of Kochi recorded an increase of 0.60C and the loss of green cover has contributed to the increased temperature. Moreover, the LST exhibits a strong positive correlation with built up land expansion. The study findings stand helpful for urban planning and sustainable development of the city.

Raised seasonal temperatures reinforce autumn Varroa destructor infestation in honey bee colonies

Varroa destructor is the main pest of the honey bee Apis mellifera, causing colony losses. We investigated the effect of temperature on the autumn abundance of V. destructor in bee colonies over 1991–2020 in Central Europe. We tested the hypothesis that temperature can affect autumn mite populations with different time-lags modulating the bee abundance and brood availability. We showed that raised spring (March–May) and autumn (October) temperatures reinforce autumn V. destructor infestation in the bee colonies. The critical temperature signals embrace periods of bee activity, i.e., just after the first cleansing flights and just before the last observed bee flights, but no direct effects of phenological changes on V. destructor abundance were found. These effects were potentially associated with increased bee reproduction in the specific periods of the year and not with the extended period of activity or accelerated spring onset. We found significant effects of autumn bee abundance, autumn capped brood abundance, and the number of colonies merged on autumn mite infestation. We also observed differences in V. destructor abundance between bees derived from different subspecies. We indicated that climatic effects, through influence on the bee abundance and brood availability, are one of the main drivers regulating V. destructor abundance.