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Publisher: London : Nature Publishing Group Ɨ Subject: article Ɨ Subject: human Ɨ

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Now showing 1 - 4 of 4
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    When optimization for governing human-environment tipping elements is neither sustainable nor safe
    (London : Nature Publishing Group, 2018) Barfuss, W.; Donges, J.F.; Lade, S.J.; Kurths, J.
    Optimizing economic welfare in environmental governance has been criticized for delivering short-term gains at the expense of long-term environmental degradation. Different from economic optimization, the concepts of sustainability and the more recent safe operating space have been used to derive policies in environmental governance. However, a formal comparison between these three policy paradigms is still missing, leaving policy makers uncertain which paradigm to apply. Here, we develop a better understanding of their interrelationships, using a stylized model of human-environment tipping elements. We find that no paradigm guarantees fulfilling requirements imposed by another paradigm and derive simple heuristics for the conditions under which these trade-offs occur. We show that the absence of such a master paradigm is of special relevance for governing real-world tipping systems such as climate, fisheries, and farming, which may reside in a parameter regime where economic optimization is neither sustainable nor safe.
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    Communication activity in a social network: Relation between long-term correlations and inter-event clustering
    (London : Nature Publishing Group, 2012) Rybski, D.; Buldyrev, S.V.; Havlin, S.; Liljeros, F.; Makse, H.A.
    Human communication in social networks is dominated by emergent statistical laws such as non-trivial correlations and temporal clustering. Recently, we found long-term correlations in the user's activity in social communities. Here, we extend this work to study the collective behavior of the whole community with the goal of understanding the origin of clustering and long-term persistence. At the individual level, we find that the correlations in activity are a byproduct of the clustering expressed in the power-law distribution of inter-event times of single users, i.e. short periods of many events are separated by long periods of no events. On the contrary, the activity of the whole community presents long-term correlations that are a true emergent property of the system, i.e. they are not related to the distribution of inter-event times. This result suggests the existence of collective behavior, possibly arising from nontrivial communication patterns through the embedding social network.
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    Correlating the ancient Maya and modern european calendars with high-precision AMS 14C dating
    (London : Nature Publishing Group, 2013) Kennett, D.J.; Hajdas, I.; Culleton, B.J.; Belmecheri, S.; Martin, S.; Neff, H.; Awe, J.; Graham, H.V.; Freeman, K.H.; Newsom, L.; Lentz, D.L.; Anselmetti, F.S.; Robinson, M.; Marwan, N.; Southon, J.; Hodell, D.A.; Haug, G.H.
    The reasons for the development and collapse of Maya civilization remain controversial and historical events carved on stone monuments throughout this region provide a remarkable source of data about the rise and fall of these complex polities. Use of these records depends on correlating the Maya and European calendars so that they can be compared with climate and environmental datasets. Correlation constants can vary up to 1000 years and remain controversial.Wereport a series of high-resolution AMS14C dates on a wooden lintel collected from the Classic Period city of Tikal bearing Maya calendar dates. The radiocarbon dates were calibrated using a Bayesian statistical model and indicate that the dates were carved on the lintel betweenAD 658-696. This strongly supports the Goodman-Mart?nez-Thompson (GMT) correlation and the hypothesis that climate change played an important role in the development and demise of this complex civilization.
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    Two-thirds of global cropland area impacted by climate oscillations
    (London : Nature Publishing Group, 2018) Heino, M.; Puma, M.J.; Ward, P.J.; Gerten, D.; Heck, V.; Siebert, S.; Kummu, M.
    The El NiƱo Southern Oscillation (ENSO) peaked strongly during the boreal winter 2015-2016, leading to food insecurity in many parts of Africa, Asia and Latin America. Besides ENSO, the Indian Ocean Dipole (IOD) and the North Atlantic Oscillation (NAO) are known to impact crop yields worldwide. Here we assess for the first time in a unified framework the relationships between ENSO, IOD and NAO and simulated crop productivity at the sub-country scale. Our findings reveal that during 1961-2010, crop productivity is significantly influenced by at least one large-scale climate oscillation in two-thirds of global cropland area. Besides observing new possible links, especially for NAO in Africa and the Middle East, our analyses confirm several known relationships between crop productivity and these oscillations. Our results improve the understanding of climatological crop productivity drivers, which is essential for enhancing food security in many of the most vulnerable places on the planet.