Abstract:Hampel et al. [2015, hereinafter Ha15] recently commented on our study [Steffen et al., 2014a], which investigates the effect of stress and fault parameters on fault slip magnitude and activation time during a glacial cycle using a newly developed two-dimensional glacial isostatic adjustment (GIA)-fault model [Steffen et al., 2014b]. In summary, Ha15 criticize the following parts of our study stating "(1) that Steffen et al.[2014a] describe our modeling approach in a misleading way, (2) that they do not menti… Show more
“…The ice and ocean load are then applied together to the Earth model to obtain GIA-induced displacement and stresses. However, the usage of the finite-element methodology in ABAQUS requires the transformation of the obtained stress tensor to GIA stresses (Steffen et al, 2015) while the displacement vector is the same. The calculated GIA stresses are then combined with tectonic background stresses to analyse the potential for GIF reactivation (Steffen et al, 2014b).…”
Due to their large mass, ice sheets induce significant stresses in the Earth’s crust. Stress release during deglaciation can trigger large-magnitude earthquakes, as indicated by surface faults in northern Europe. Although glacially-induced stresses have been analyzed in northern Europe, they have not yet been analyzed for Greenland. We know that the Greenland Ice Sheet experienced a large melting period in the early Holocene, and so here, we analyze glacially-induced stresses during deglaciation for Greenland for the first time. Instability occurs in southern Greenland, where we use a combined analysis of past sea level indicators and a model of glacially-triggered fault reactivation to show that deglaciation of the Greenland Ice Sheet may have caused a large magnitude earthquake around 10,600 years ago offshore south-western Greenland. The earthquake may have shifted relative sea level observations by several meters. If the earthquake-induced stress release was created during a single event, it could have produced a tsunami in the North Atlantic Ocean with runup heights of up to 5 m in the British Isles and up to 7.5 m along Canadian coasts.
“…The ice and ocean load are then applied together to the Earth model to obtain GIA-induced displacement and stresses. However, the usage of the finite-element methodology in ABAQUS requires the transformation of the obtained stress tensor to GIA stresses (Steffen et al, 2015) while the displacement vector is the same. The calculated GIA stresses are then combined with tectonic background stresses to analyse the potential for GIF reactivation (Steffen et al, 2014b).…”
Due to their large mass, ice sheets induce significant stresses in the Earth’s crust. Stress release during deglaciation can trigger large-magnitude earthquakes, as indicated by surface faults in northern Europe. Although glacially-induced stresses have been analyzed in northern Europe, they have not yet been analyzed for Greenland. We know that the Greenland Ice Sheet experienced a large melting period in the early Holocene, and so here, we analyze glacially-induced stresses during deglaciation for Greenland for the first time. Instability occurs in southern Greenland, where we use a combined analysis of past sea level indicators and a model of glacially-triggered fault reactivation to show that deglaciation of the Greenland Ice Sheet may have caused a large magnitude earthquake around 10,600 years ago offshore south-western Greenland. The earthquake may have shifted relative sea level observations by several meters. If the earthquake-induced stress release was created during a single event, it could have produced a tsunami in the North Atlantic Ocean with runup heights of up to 5 m in the British Isles and up to 7.5 m along Canadian coasts.
“…The interaction between the living organisms on this planet and the physical climate system controls the state of the overall global environment, so the loss of biodiversity reduces the resilience of the biosphere, which is essential for maintaining the climate conditions we enjoy on Earth. 707 Extinctions reduce the genetic diversity of the biosphere, and thus the resilience of biosphere functions under changing climate conditions. The pace at which biodiversity is being lost is unprecedented with currently nearly 1 million species, or 25 per cent of the assessed animals and plants, being threatened by extinction in the coming decades.…”
decided that the report would be produced quadrennially by an independent group of scientists appointed by the United Nations Secretary-General and comprising 15 experts representing a variety of backgrounds, scientific disciplines and institutions, with geographical and gender balance.
“…For example, the website of the Convention on Biological Diversity suggests that current deficiencies in taxonomic knowledge impact on 'our ability to conserve, use and share the benefits of our biological diversity'. 32 Can species richness play a comparable role in biodiversity policy to that of global mean temperature or the partial pressure of Carbon Dioxide (pCO 2 )a measure of the state of the climate system that is linked mechanistically to whether the earth system will change in a way that endangers society 33 in climate-change policy? Although no single number can ever capture the full hierarchical complexity of the composition, structure and function of biodiversity 34 or even the biodiversity represented in a single sample 35 might species richness nonetheless be a sufficiently accurate short-cut to form the basis for policy?…”
Section: Calculating Biodiversity For Policymentioning
After the launch of the Global Assessment of the Intergovernmental Platform for Biodiversity and Ecosystem Services (IPBES) in May 2019, the message that 1 million species are threatened with extinction made headlines in news and social media across the world. These headlines also resulted in critical responses that questioned the credibility of this number andby extensionthe Global Assessment report and the institution of IPBES. In this article, weas two authors of the Global Assessmentdraw lessons from the GA about how to represent biodiversity in assessments and how biodiversity knowledge can inform effective and legitimate actions that contribute to conservation as well as equity, justice, and human well-being. Specifically, we highlight the inherent multiplicity of meanings and definitions of biodiversity to reflect on the limitations of using species richness and extinction as proxies for biodiversity and biodiversity loss. It is crucial to communicate clearly and in a balanced way that biodiversity loss is broader than species extinction, and how this broader loss of biodiversity jeopardises human wellbeing irrespective of whether species die out. Consequently, the post-2020 biodiversity framework will require multiple targets around not only species extinction but also broader biodiversity loss and human well-being.
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