This chapter discusses leading problems linked to energy that the world is now confronting and to propose some ideas concerning possible solutions. Oil deserves special attention among all energy sources. Since the beginning of 1981, it has merely been continuing and enhancing the downward movement in consumption and prices caused by excessive rises, especially for light crudes such as those from Africa, and the slowing down of worldwide economic growth. Densely-populated oil-producing countries need to produce to live, to pay for their food and their equipment. If the economic growth of the industrialized countries were to be 4%, even if investment in the rational use of energy were pushed to the limit and the development of nonpetroleum energy sources were also pursued actively, it would be extremely difficult to prevent a sharp rise in prices. It is evident that it is absolutely necessary to pursue actively the development of coal, natural gas, and nuclear power if a physical shortage of energy is not to block economic growth.

World energy outlook

The hippocampus and the medial entorhinal cortex are part of a brain system that maps self-location during navigation in the proximal environment1,2. In this system, correlations between neural firing and an animal’s position or orientation are so evident that cell types have been given simple descriptive names, such as place cells3, grid cells4, border cells5,6 and head-direction cells7. While the number of identified functional cell types is growing at a steady rate, insights remain limited by an almost-exclusive reliance on recordings from rodents foraging in empty enclosures that are different from the richly populated, geometrically irregular environments of the natural world. In environments that contain discrete objects, animals are known to store information about distance and direction to those objects and to use this vector information to guide navigation8–10. Theoretical studies have proposed that such vector operations are supported by neurons that use distance and direction from discrete objects11,12 or boundaries13,14 to determine the animal’s location, but—although some cells with vector-coding properties may be present in the hippocampus15 and subiculum16,17—it remains to be determined whether and how vectorial operations are implemented in the wider neural representation of space. Here we show that a large fraction of medial entorhinal cortex neurons fire specifically when mice are at given distances and directions from spatially confined objects. These ‘object-vector cells’ are tuned equally to a spectrum of discrete objects, irrespective of their location in the test arena, as well as to a broad range of dimensions and shapes, from point-like objects to extended surfaces. Our findings point to vector coding as a predominant form of position coding in the medial entorhinal cortex. Cells in the mouse medial entorhinal cortex that fire when mice are at a specific distance and direction from a stationary object suggest that vector coding is important for rodent navigation.

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Object-vector coding in the medial entorhinal cortex

Sand and dust storms (SDS) play an integral role in the Earth system but they also present a range of hazards to the environmental and economic sustainability of human society. These hazards are of considerable importance for residents of dryland environments and also affect people beyond drylands because wind erosion can occur in most environments and desert dust events often involve long-range transport over great distances (>1000 km). This paper makes an assessment of the scale of SDS impacts by totalling the countries affected using an appraisal of peer-reviewed published sources, arriving at a conservative estimate that 77% of all parties to the United Nations Convention to Combat Desertification (UNCCD) are affected directly by SDS issues. We then present a synthesis of the environmental management techniques designed to mitigate SDS hazards for disaster risk reduction and review policy measures, both historical and contemporary, for SDS impact mitigation. Although many SDS hazards are well-known, the processes involved and their impacts are not all equally well-understood. Policies designed to mitigate the impacts of wind erosion in agricultural areas have been developed in certain parts of the world but policies designed to mitigate the wider impacts of SDS, including many that are transboundary, are geographically patchy and have a much shorter history. Further development and wider implementation of such policies is advocated because of the recent marked increase in wind erosion and associated dust storms in several parts of the world.

Sand and Dust Storms: Impact Mitigation

The atmospheric methane burden is increasing rapidly, contrary to pathways compatible with the goals of the 2015 United Nations Framework Convention on Climate Change Paris Agreement. Urgent action is required to bring methane back to a pathway more in line with the Paris goals. Emission reduction from “tractable” (easier to mitigate) anthropogenic sources such as the fossil fuel industries and landfills is being much facilitated by technical advances in the past decade, which have radically improved our ability to locate, identify, quantify, and reduce emissions. Measures to reduce emissions from “intractable” (harder to mitigate) anthropogenic sources such as agriculture and biomass burning have received less attention and are also becoming more feasible, including removal from elevated-methane ambient air near to sources. The wider effort to use microbiological and dietary intervention to reduce emissions from cattle (and humans) is not addressed in detail in this essentially geophysical review. Though they cannot replace the need to reach “net-zero” emissions of CO2, significant reductions in the methane burden will ease the timescales needed to reach required CO2 reduction targets for any particular future temperature limit. There is no single magic bullet, but implementation of a wide array of mitigation and emission reduction strategies could substantially cut the global methane burden, at a cost that is relatively low compared to the parallel and necessary measures to reduce CO2, and thereby reduce the atmospheric methane burden back toward pathways consistent with the goals of the Paris Agreement.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2019RG000675

Methane Mitigation: Methods to Reduce Emissions, on the Path to the Paris Agreement

Disturbances in forests can kill mature trees, but also create the conditions necessary for the establishment of new tree cohorts and create micro-habitats for new plant and animal species, thereby increasing the species diversity compared to undisturbed stands. We review the types and intensities of disturbances on forests in three regions of the temperate zone of the northern hemisphere: northeastern North America, Central Europe, and East Asia. We focus on (1) the ways in which disturbances affect forest stand development; (2) the differences among the three areas in this regard; (3) the consequences for future forest management. In both northeastern North America and East Asia, hurricanes and typhoons represent the major mode of natural disturbance, while in Central Europe winter windstorms occur after deciduous trees have lost their leaves. Tornadoes can have even greater destructive power (but affect relatively narrow strips of land), and the more severe of these mainly occur in North America. The general disturbance patch system therefore is relatively large in northeastern North America, small in Central Europe, and of intermediate size in temperate East Asia. In addition to wholly natural disturbance factors, human commerce and globalization have enabled new disturbance types by introducing pests and diseases from one region to another. In North America especially, several of the most important foundation species in temperate forests are strongly affected, so that not just the species composition but also the whole forest structure is changing fundamentally. In all three areas in the past the change in land use by growing human populations strongly affected the structure as well as the species composition of forests. Nearly all the recent forest stands of the temperate zone had been used in the past in a particular way, and many of today’s forests had previously been converted into agricultural land. Finally climate change is superimposing itself on forest development worldwide. Nevertheless, climate change is not a new phenomenon, so forest ecosystems in all time periods have been exposed to changing climatic conditions and have had to adapt. Each forest stand therefore represents a unique recent expression of the interaction of environmental conditions and plant species, a “snapshot” of the relevant abiotic and biotic factors, including human impact.

Disturbances in deciduous temperate forest ecosystems of the northern hemisphere: their effects on both recent and future forest development

https://iopscience.iop.org/article/10.1088/1748-9326/ab0cc3/pdf

A review of close-range and screening technologies for mitigating fugitive methane emissions in upstream oil and gas

/pdf/agricultural-land-use-change-in-kerala-india-perspectives-42etdfj6kz.pdf

Agricultural land-use change in Kerala, India : perspectives from above and below the canopy

Interest has grown in using new screening technologies such as drones to search for methane leaks in hydrocarbon production infrastructure. Screening technologies may be less expensive and faster than traditional methods. However, including new technologies in emissions monitoring programs requires an accurate understanding of what leaks a system will detect and the resultant emissions mitigation. Here we examine source detection of a drone-based system with controlled releases. We examine different detection algorithm parameters to understand trade-offs between false positive rate and detection probability. Leak detection was poor under all conditions with an average detection probability of 0.21. Detection probability was not affected by emission rate, suggesting similar systems may commonly miss large leaks. Detection was best in moderate wind speeds and at 750–2000 m downwind from the source where the plume had diffused vertically above the minimum flight level of 40–50 m. Predicted concentration enhancement from a Gaussian plume model was a reasonable predictor of detection within the test suite. Enabling lower flight elevations may increase detection probability. Overall, the experiments suggest that controlled releases are useful and necessary to provide an understanding of detection probability of screening technologies for regulatory and deployment purposes, and the testing must be representative to support broad application.

Plume detection modeling of a drone-based natural gas leak detection system

Blowing dust from agricultural fields has serious health and economic effects, which can be mitigated by soil conservation techniques. However, it is difficult to isolate improved land management in downstream records of airborne dust. In this letter we present multi-decadal (1961‐2006) records of airborne dust frequency from seven weather stations across the Canadian Prairies. We related temporal changes in dust frequency to the climatic wind erosion potential and agricultural census data. We identified a statistically significant regime shift in the region-wide dust time series at 1990, with a substantial reduction in dust frequency thereafter. The correspondence between dust frequency and the climatic wind erosion potential improved from 1961‐90 (r 2 D 0:154, p< 0:001) to 1991‐2006 (r 2 D 0:429, p< 0:001). We interpret this as indicating that the climate signal was obscured by poor soil conservation practices in 1961‐90, leading to dustier conditions. Post 1990, improved land management reduced the impact of land-use practices; only the most severe climate forcings resulted in detectable dust. The dramatic reduction of dust from 1990 onward appears to represent a region-wide threshold crossing, where the effects of soil conservation efforts began to materialize. Overall, the results suggest that soil conservation initiatives have had an impact in reducing airborne dust on the Canadian Prairies.

Successes of soil conservation in the Canadian Prairies highlighted by a historical decline in blowing dust

Small aerial drones are used in a growing number of commercial applications. However, drones cannot fly in all weather, which impacts their reliability for time-sensitive operations. The magnitude and global variability of weather impact is poorly understood. We explore weather-limited drone flyability (the proportion of time drones can fly safely) by comparing historical wind speed, temperature, and precipitation data to manufacturer-reported thresholds of common commercial and weather-resistant drones with a computer simulation. We show that global flyability is highest in warm and dry continental regions and lowest over oceans and at high latitudes. Median global flyability for common drones is low: 5.7 h/day or 2.0 h/day if restricted to daylight hours. Weather-resistant drones have higher flyability (20.4 and 12.3 h/day, respectively). While these estimates do not consider all weather conditions, results suggest that improvements to weather resistance can increase flyability. An inverse analysis for major population centres shows the largest flyability gains for common drones can be achieved by increasing maximum wind speed and precipitation thresholds from 10 to 15 m/s and 0-1 mm/h, respectively.

/pdf/weather-constraints-on-global-drone-flyability-1x8nzs293g.pdf

Thomas A. Fox

Papers

A review of close-range and screening technologies for mitigating fugitive methane emissions in upstream oil and gas

Agricultural land-use change in Kerala, India : perspectives from above and below the canopy

Plume detection modeling of a drone-based natural gas leak detection system

Successes of soil conservation in the Canadian Prairies highlighted by a historical decline in blowing dust

Weather constraints on global drone flyability.