16 research outputs found
Algebraic Many-Body Localization and its implications on information propagation
We probe the existence of a many-body localized phase (MBL-phase) in a
spinless fermionic Hubbard chain with algebraically localized single-particle
states, by investigating both static and dynamical properties of the system.
This MBL-phase can be characterized by an extensive number of integrals of
motion which develop algebraically decaying tails, unlike the case of
exponentially localized single-particle states. We focus on the implications
for the quantum information propagation through the system. We provide evidence
that the bipartite entanglement entropy after a quantum quench has an unbounded
algebraic growth in time, while the quantum Fisher information grows
logarithmically
Greenhouse gas emission reduction proposals and national climate policies of major economies : Policy Brief
Beyond pure offsetting: Assessing options to generate Net-Mitigation-Effects in carbon market mechanisms
The current project-based carbon market mechanisms such as the Clean Development Mechanism (CDM) and the Joint Implementation (JI) do not have a direct impact on global greenhouse gas emission levels, because they only replace or offset emissions. Nor do they contribute to host countryÂżs national greenhouse gas emission reduction targets. Contributions to net emission reductions in host countries is likely to become mandatory in new mechanisms under development such as in the framework for various approaches, a new market-based mechanism and even in a reformed JI. This research analysed the question if approaches for carbon market-based mechanisms exist that allow the generation of net emission reductions in host countries while keeping project initiation attractive. We present a criteria-based assessment method and apply it for four generic options in existing mechanisms and derive implications for future mechanism frameworks. We identified the application of âdiscountsâ on the amount of avoided emissions for the issuance of carbon credits and âstandardisation below business as usualâ as most promising options over âlimiting the crediting periodâ and âover-conservativenessâ. We propose to apply these options differentiated over project types based on internal rate of return to ensure cost-efficiency and attractiveness
Reinvigorating International Climate Policy: A Comprehensive Framework for Effective Nonstate Action
As countries negotiate a new climate agreement for the United Nations climate conference in December 2015, a groundswell of climate actions is emerging as cities, regions, businesses and civil society groups act on mitigation and adaptation, independently, with each other and with national governments and international organizations. The Paris conference provides a historic opportunity to establish a framework to catalyse, support, and steer these initiatives. Without such a framework, âbottom-upâ climate governance runs the risk of failing to deliver meaningful results. Social science research highlights the need for a comprehensive approach that promotes ambition, experimentation and accountability, and avoids unnecessary overlaps. This article specifies functions and design principles for a new, comprehensive framework for sub- and nonstate climate actions that could provide effective coordination
Countriesâ contributions to climate change: effect of accounting for all greenhouse gases, recent trends, basic needs and technological progress
In the context of recent discussions at the UN climate negotiations we compared several ways of calculating historical greenhouse gas (GHG) emissions, and assessed the effect of these different approaches on countriesâ relative contributions to cumulative global emissions. Elements not covered before are: (i) including recent historical emissions (2000â2010), (ii) discounting historical emissions to account for technological progress; (iii) deducting emissions for âbasic needsâ; (iv) including projected emissions up to 2020, based on countriesâ unconditional reduction proposals for 2020. Our analysis shows that countriesâ contributions vary significantly based on the choices made in the calculation: e.g. the relative contribution of developed countries as a group can be as high as 80 % when excluding recent emissions, non-CO2 GHGs, and land-use change and forestry CO2; or about 48 % when including all these emissions and discounting historical emissions for technological progress. Excluding non-CO2 GHGs and land-use change and forestry CO2 significantly changes relative historical contributions for many countries, altering countriesâ relative contributions by multiplicative factors ranging from 0.15 to 1.5 compared to reference values (i.e. reference contribution calculations cover the period 1850-2010 and all GHG emissions). Excluding 2000â2010 emissions decreases the contributions of most emerging economies (factor of up to 0.8). Discounting historical emissions for technological progress reduces the relative contributions of some developed countries (factor of 0.8) and increases those of some developing countries (factor of 1.2â1.5). Deducting emissions for âbasic needsâ results in smaller contributions for countries with low per capita emissions (factor of 0.3â0.5). Finally, including projected emissions up to 2020 further increases the relative contributions of emerging economies by a factor of 1.2, or 1.5 when discounting pre-2020 emissions for technological progress
National post-2020 greenhouse gas targets and diversity-aware leadership
Achieving the collective goal of limiting warming to below 2 °C or 1.5 °C compared to pre-industrial levels requires a transition towards a fully decarbonized world. Annual greenhouse gas emissions on such a path in 2025 or 2030 can be allocated to individual countries using a variety of allocation schemes. We reanalyse the IPCC literature allocation database and provide country-level details for three approaches. At this stage, however, it seems utopian to assume that the international community will agree on a single allocation scheme. Here, we investigate an approach that involves a major-economy country taking the lead. In a bottom-up manner, other countries then determine what they consider a fair comparable target, for example, either a âper-capita convergenceâ or âequal cumulative per-capitaâ approach. For example, we find that a 2030 target of 67% below 1990 for the EU28, a 2025 target of 54% below 2005 for the USA or a 2030 target of 32% below 2010 for China could secure a likely chance of meeting the 2 °C target in our illustrative default case. Comparing those targets to post-2020 mitigation targets reveals a large gap. No major emitter can at present claim to show the necessary leadership in the concerted effort of avoiding warming of 2 °C in a diverse global context
Copenhagen Accord pledges are paltry
Nations will probably meet only the lower ends of their emissions pledges in the absence of a binding international agreement Nations can bank an estimated 12 gigatonnes of Co2 equivalents surplus allowances for use after 2012 Land-use rules are likely to result in further allowance increases of 0.5 GtCO2-eq per year Global emissions in 2020 could thus be up to 20% higher than today Current pledges mean a greater than 50% chance that warming will exceed 3°C by 2100 If nations agree to halve emissions by 2050, there is still a 50% chance that warming will exceed 2°C and will almost certainly exceed 1.5°