Showing papers by "Alan Grainger published in 2017"
Food and Agriculture Organization1, Université libre de Bruxelles2, University of Leeds3, Environmental Change Institute4, United Nations Development Programme5, Google6, University of Adelaide7, Bartın University8, Sapienza University of Rome9, Technical University of Madrid10, Swedish University of Agricultural Sciences11, United States Department of Agriculture12, World Resources Institute13
TL;DR: An estimate of global forest extent in dryland biomes is reported, based on analyzing more than 210,000 0.5-hectare sample plots through a photo-interpretation approach using large databases of satellite imagery at very high spatial resolution and very high temporal resolution, available through the Google Earth platform.
Abstract: Dryland biomes cover two-fifths of Earth’s land surface, but their forest area is poorly known. Here, we report an estimate of global forest extent in dryland biomes, based on analyzing more than 210,000 0.5-hectare sample plots through a photo-interpretation approach using large databases of satellite imagery at (i) very high spatial resolution and (ii) very high temporal resolution, which are available through the Google Earth platform. We show that in 2015, 1327 million hectares of drylands had more than 10% tree-cover, and 1079 million hectares comprised forest. Our estimate is 40 to 47% higher than previous estimates, corresponding to 467 million hectares of forest that have never been reported before. This increases current estimates of global forest cover by at least 9%.
302 citations
TL;DR: A Conceptual Framework for Earth Observation is proposed which can be used in a new Earth observation science to explain blockages in the chain from collecting data to disseminating information in any Earth observation system, including remote sensing systems.
Abstract: Earth observation is diversifying, and now includes new types of systems, such as citizen observatories, unmanned aerial vehicles and wireless sensor networks. However, the Copernicus Programme vision of a seamless chain from satellite data to usable information in the hands of decision makers is still largely unrealized, and remote sensing science lacks a conceptual framework to explain why. This paper reviews the literatures on citizen science, citizen observatories and conceptualization of remote sensing systems. It then proposes a Conceptual Framework for Earth Observation which can be used in a new Earth observation science to explain blockages in the chain from collecting data to disseminating information in any Earth observation system, including remote sensing systems. The framework differs from its predecessors by including social variables as well as technological and natural ones. It is used here, with evidence from successful citizen science projects, to compare the factors that are likely to influence the effectiveness of satellite remote sensing systems and citizen observatories. The paper finds that constraints on achieving the seamless “Copernicus Chain” are not solely technical, as assumed in the new Space Strategy for Europe, but include social constraints too. Achieving the Copernicus Chain will depend on the balance between: (a) the ‘forward’ momentum generated by the repetitive functioning of each component in the system, as a result of automatic operation or human institutions, and by the efficiency of interfaces between components; and (b) the ‘backward’ flow of information on the information needs of end users. Citizen observatories will face challenges in components which for satellite remote sensing systems are: (a) automatic or straightforward, e.g., sensor design and launch, data collection, and data products; and (b) also challenging, e.g., data processing. Since citizen observatories will rely even more on human institutions than remote sensing systems to achieve repetitive functioning, one of their greatest strengths—using a “crowd” of hand-held sensors to cover large areas—could also be one of their greatest weaknesses.
38 citations
TL;DR: In this article, an alternative framework for conceptualizing the transition between Stages 2 and 3 of the Anthropocene epoch is proposed, which generates the hypothesis that some biophysical processes will change at rates proportional to the difference between the carbon dioxide concentration of the atmosphere and the threshold level, and to the rate of climate change.
13 citations
TL;DR: The authors explain why the differences they report result from a difference of technique and not of definition, and how anyone can adapt—as they did—their data set to any forest definition and tree cover threshold of interest.
Abstract: De la Cruz et al . question the reliability of our results, claiming that we do not refer to the most appropriate spatial extent of drylands. In our response, we explain why we chose an existing and internationally recognized delineation of drylands among several options, and why our findings are due to a difference of remote sensing technique and not to the definition of drylands we have selected.
6 citations