Jupiter - friend or foe? II: the Centaurs

It has long been assumed that the planet Jupiter acts as a giant shield, significantly lowering the impact rate of minor bodies upon the Earth, and thus enabling the development and evolution of life in a collisional environment which is not overly hostile. However, in the past, little work has been carried out to examine the validity of this idea. In the second of a series of papers, we examine the degree to which the impact risk resulting from objects on Centaur-like orbits is affected by the presence of a giant planet, in a continuing attempt to fully understand the impact regime under which life on Earth has developed. The Centaurs, which occupy orbits beyond Jupiter, have their origins in the Edgeworth-Kuiper belt that extends beyond Neptune. The giant planets peturb the Centaurs, sending a significanr fraction into the inner Solar System where they become visible as short-period comets. In this work we present results which show that the presence of a giant planet can act to significantly change the impact rate of short-period comets on the Earth, and that a giant planet often actually increases the impact flux greatly over that which would be expected were it not present. (Shortened version of abstract.)Comment: 13 pages, 1 Figur

Framing the Global Pact for the Environment: Why It\u27s Needed, What It Does, and How It Does It

We face a critical environmental crisis. Humanity consumes unsustainably; we use resources at a rate fifty percent faster than they are reproduced by the planet. The population is growing exponentially and climate change, the most important challenge of this century, is already wreaking havoc around the world. Despite numerous existing international environmental treaties, the Earth, and, therefore, human safety and prosperity, is in peril. According to a recent study by scientists from Stanford University and the National Autonomous University of Mexico, the ongoing “sixth mass extinction” threatens to cause an “assault on the foundations of human civilization.” In November 2017, a report signed by more than 15,000 scientists from 184 countries warned that without a drastic change, we risk catastrophic disruption to Earth systems that enable life on this planet. According to the 2018 Intergovernmental Panel on Climate Change special report, states have already begun to take the kinds of actions needed to avoid some of those catastrophic events, but those efforts need to be rapidly accelerated and scaled

Jupiter – friend or foe? I: the asteroids

The asteroids are a major source of potential impactors on the Earth today. It has long been assumed that the giant planet Jupiter acts as a shield, significantly lowering the impact rate on the Earth from both cometary and asteroidal bodies. Such shielding, it is claimed, enabled the development and evolution of life in a collisional environment, which is not overly hostile. The reduced frequency of impacts, and of related mass extinctions, would have allowed life the time to thrive, where it would otherwise have been suppressed. However, in the past, little work has been carried out to examine the validity of this idea. In the first of several papers, we examine the degree to which the impact risk resulting from a population representative of the asteroids is enhanced or reduced by the presence of a giant planet, in an attempt to understand fully the impact regime under which life on Earth developed. Our results show that the situation is far less clear cut that has previously been assumed, that is, the presence of a giant planet can act to enhance the impact rate of asteroids on the Earth significantly

The science-policy interfaces of the European network for observing our changing planet : From Earth Observation data to policy-oriented decisions

This paper reports on major outcomes of the ERA-PLANET (The European network for observing our changing planet) project, which was funded under Horizon 2020 ERA-net co-funding scheme. ERA-PLANET strengthened the European Research Area in the domain of Earth Observation (EO) in coherence with the European partici-pation to Group on Earth Observation and the Copernicus European Union's Earth Observation programme. ERA -PLANET was implemented through four projects focused on smart cities and resilient societies (SMURBS), resource efficiency and environmental management (GEOEssential), global changes and environmental treaties (iGOSP) and polar areas and natural resources (iCUPE). These projects developed specific science-policy workflows and interfaces to address selected environmental policy issues and design cost-effective strategies aiming to achieve targeted objectives. Key Enabling Technologies were implemented to enhancing 'data to knowledge' transition for supporting environmental policy making. Data cube technologies, the Virtual Earth Laboratory, Earth Observation ontologies and Knowledge Platforms were developed and used for such applications.SMURBS brought a substantial contribution to resilient cities and human settlements topics that were adopted by GEO as its 4th engagement priority, bringing the urban resilience topic in the GEO agenda on par with climate change, sustainable development and disaster risk reduction linked to environmental policies. GEOEssential is contributing to the development of Essential Variables (EVs) concept, which is encouraging and should allow the EO community to complete the description of the Earth System with EVs in a close future. This will clearly improve our capacity to address intertwined environmental and development policies as a Nexus.iGOSP supports the implementation of the GEO Flagship on Mercury (GOS4M) and the GEO Initiative on POPs (GOS4POPs) by developing a new integrated approach for global real-time monitoring of environmental quality with respect to air, water and human matrices contamination by toxic substances, like mercury and persistent organic pollutants. iGOSP developed end-user-oriented Knowledge Hubs that provide data repository systems integrated with data management consoles and knowledge information systems.The main outcomes from iCUPE are the novel and comprehensive data sets and a modelling activity that contributed to delivering science-based insights for the Arctic region. Applications enable defining and moni-toring of Arctic Essential Variables and sets up processes towards UN2030 SDGs that include health (SDG 3), clean water resources and sanitation (SDGs 6 and 14).Peer reviewe

Planetary Quotas and the Planetary Accounting Framework Comparing Human Activity to Global Environmental Limits

Human activity is putting us at risk of altering the planet from hospitable to hostile. The Planetary Quotas are scientific limits for human activity, based on global environmental limits. The Planetary Accounting Framework is a new way to manage the Earth System using the Quotas in a poly-scalar approach. The framework allows meaningful decisions to be made at any level, and in any sector regarding policy, planning, technology and innovation, business operations, legislation and behaviour