Uncertainty management in the IPCC: agreeing to disagree

Looking back over three and a half Assessment Reports, we see that the Intergovernmental Panel on Climate Change (IPCC) has given increasing attention to the management and reporting of uncertainties, but coordination across working groups (WGs) has remained an issue. We argue that there are good reasons for working groups to use different methods to assess uncertainty, thus it is better that working groups agree to disagree rather than seek to bring everybody on one party line.IPCC; uncertainty

Anticipatory control of human gait following simulated slip exposure

A cautious gait (CG), marked by wider and shorter steps, is typically employed to mitigate expected perturbations proactively. However, it is not well understood if and how CG is informed by the task requirements. Therefore, we assessed how CG is adjusted to these requirements. Three groups of ten healthy young adults were exposed to a single uninterrupted protocol of treadmill walking that consisted of three distinct phases. Spatiotemporal step characteristics and margins of stability of the unperturbed strides were compared when participants were (i) only warned of a perturbation, (ii) exposed to fifty unilateral (right) slip-like perturbations and (iii) kept unaware of perturbation removal. Only the perturbation intensity predictability differed between groups. This was either kept consistent or pseudo-randomly or randomly varied. Participants walked with wider and shorter steps following the perturbation warning. However, this extinguished in continuing perturbation absence. Next, during perturbation exposure, participants shortened the step of the perturbed but increased the step of the unperturbed leg. This did not differ between groups. Finally, participants persisted in displaying CG on perturbation removal, but this extinguished over time. Collectively, we show that CG is functionally adjusted to the task requirements. These findings may have practical implications for fall-prevention training

Singular Spectrum Analysis as a data-driven approach to the analysis of motor adaptation time series

Motor adaptation is a form of learning to re-establish desired movements in novel situations. To probe motor adaptation, one can replicate such conditions experimentally by imposing a sustained perturbation during movement. Exposure to such perturbations initially causes an abrupt change in relevant performance variables, followed by a gradual return to baseline behaviour. The resulting time series exhibit persistent properties related to structural changes in underlying motor control and transitory properties related to trial-to-trial variations. The global trend, signifying the structural change, is often assessed by averaging the time series in predefined bins or nonlinear model fitting. However, these methods to study motor adaptation require a priori decisions to produce accurate fits. Here, we test a data-driven approach called Singular Spectrum Analysis (SSA) to assess the global trend. In SSA, we first decompose the adaptation time series into components that represent either a global trend or additional variations, and secondly, select the component(s) corresponding to the global trend using spectral analysis. In this paper, we will use simulated data to compare the reconstruction performance of SSA with often applied filter and fitting methods in motor adaptation studies and apply SSA to real data obtained during split- belt adaptation. In the simulations, we show that SSA reconstructed the fast-initial component and entire global trends more accurately than the filtering and fitting methods. In addition, we show that SSA also successfully reconstructed global trends from real data. Therefore, the SSA might be useful in motor learning studies to decompose and assess adaptation time series

From Urban Façade to Green Foundation: Re-Imagining the Garden City to Manage Climate Risks

Climate risk management evolves rapidly from one additional challenge for urban planning into a radical driver of urban development. In addition to fundamental changes in urban planning to increase long-term resilience, the creation of new opportunities for sustainable transformation is imperative. While urban planners increasingly add climate risks to their menu, implementation of effective action is lagging. To reduce urban infrastructure's vulnerability to heat and flooding, cities often rely on short-term incremental adjustments rather than considering longer-term transformative solutions. The transdisciplinary co-development of inspiring urban visions with local stakeholders over timescales of decades or more, can provide an appealing prospect of the city we desire - a city that is attractive to live and work in, and simultaneously resilient to climate hazards. Taking an historic perspective, we argue that re-imagining historical urban planning concepts, such as the late 19th-century garden city until early 21st century urban greening through nature-based solutions, is a pertinent example of how climate risk management can be combined with a wide-range of socio-economic and environmental goals. Climate knowledge has expanded rapidly over the last decades. However, climate experts mainly focus on the refinement of and access to observations and model results, rather than on translating their knowledge effectively to meet today’s urban planning needs. In this commentary we discuss how the two associated areas (urban planning and climate expertise) should be more fully integrated to address today’s long-term challenges effectively

Event Generation and Statistical Sampling for Physics with Deep Generative Models and a Density Information Buffer

We present a study for the generation of events from a physical process with deep generative models. The simulation of physical processes requires not only the production of physical events, but also to ensure these events occur with the correct frequencies. We investigate the feasibility of learning the event generation and the frequency of occurrence with Generative Adversarial Networks (GANs) and Variational Autoencoders (VAEs) to produce events like Monte Carlo generators. We study three processes: a simple two-body decay, the processes $e^+e^-\to Z \to l^+l^-$ and $p p \to t\bar{t}$ including the decay of the top quarks and a simulation of the detector response. We find that the tested GAN architectures and the standard VAE are not able to learn the distributions precisely. By buffering density information of encoded Monte Carlo events given the encoder of a VAE we are able to construct a prior for the sampling of new events from the decoder that yields distributions that are in very good agreement with real Monte Carlo events and are generated several orders of magnitude faster. Applications of this work include generic density estimation and sampling, targeted event generation via a principal component analysis of encoded ground truth data, anomaly detection and more efficient importance sampling, e.g. for the phase space integration of matrix elements in quantum field theories.Comment: 24 pages, 10 figure

Multi-gas Emissions Pathways to Meet Climate Targets

So far, climate change mitigation pathways focus mostly on CO2 and a limited number of climate targets. Comprehensive studies of emission implications have been hindered by the absence of a flexible method to generate multi-gas emissions pathways, user-definable in shape and the climate target. The presented method ‘Equal Quantile Walk' (EQW) is intended to fill this gap, building upon and complementing existing multi-gas emission scenarios. The EQW method generates new mitigation pathways by ‘walking along equal quantile paths' of the emission distributions derived from existing multi-gas IPCC baseline and stabilization scenarios. Considered emissions include those of CO2 and all other major radiative forcing agents (greenhouse gases, ozone precursors and sulphur aerosols). Sample EQW pathways are derived for stabilization at 350 ppm to 750 ppm CO2 concentrations and compared to WRE profiles. Furthermore, the ability of the method to analyze emission implications in a probabilistic multi-gas framework is demonstrated. The probability of overshooting a 2 ∘C climate target is derived by using different sets of EQW radiative forcing peaking pathways. If the probability shall not be increased above 30%, it seems necessary to peak CO2 equivalence concentrations around 475 ppm and return to lower levels after peaking (below 400 ppm). EQW emissions pathways can be applied in studies relating to Article 2 of the UNFCCC, for the analysis of climate impacts, adaptation and emission control implications associated with certain climate targets. See http://www.simcap.org for EQW-software and dat

IPCC emission scenarios: How did critiques affect their quality and relevance 1990–2022?

Long-term global emission scenarios enable the analysis of future climate change, impacts, and response strategies by providing insight into possible future developments and linking these different climate research elements. Such scenarios play a crucial role in the climate change literature informing the Intergovernmental Panel on Climate Change’s (IPCC) Assessment Reports (ARs) and support policymakers. This article reviews the evolution of emission scenarios, since 1990, by focusing on scenario critiques and responses as published in the literature. We focus on the issues raised in the critiques and the possible impact on scenario development. The critique (280) focuses on four areas: 1) key scenario assumptions (40%), 2) the emissions range covered by the scenarios and missing scenarios (25%), 3) methodological issues (24%), and 4) the policy relevance and handling of uncertainty (11%). Scenario critiques have become increasingly influential since 2000. Some areas of critique have decreased or become less prominent (probability, development process, convergence assumptions, and economic metrics). Other areas have become more dominant over time (e.g., policy relevance & implications of scenarios, transparency, Negative Emissions Technologies (NETs) assumptions, missing scenarios). Several changes have been made in developing scenarios and their content that respond to the critique.info:eu-repo/semantics/publishedVersio

Split-belt walking:An experience that is hard to forget

BACKGROUND. The common paradigm to study the adaptability of human gait is split-belt walking. Short-term savings (minutes to days) of split-belt adaptation have been widely studied to gain knowledge in locomotor learning but reports on long-term savings are limited. Here, we studied whether after a prolonged inter-exposure interval (three weeks), the newly acquired locomotor pattern is subject to forgetting or that the pattern is saved in long-term locomotor memory. RESEARCH QUESTION. Can savings of adaptation to split-belt walking remain after a prolonged interexposure interval of three weeks? METHODS. Fourteen healthy adults participated in a single tenminute adaptation session to split-belt walking and five-minute washout to tied-belt walking. They received no training after the first exposure and returned to the laboratory exactly three weeks later for the second exposure. To identify the adaptation trends and quantify saving parameters we used Singular Spectrum Analysis, a non-parametric, data-driven approach. We identified trends in step length asymmetry and double support asymmetry, and calculated the adaptation volume (reduction in asymmetry over the course of adaptation), and the plateau time (time required for the trend to level off). RESULTS. At the second exposure after three weeks, we found substantial savings in adaptation for step length asymmetry volume (61.6% – 67.6% decrease) and plateau time (76.3% decrease). No differences were found during washout or in double support asymmetry. SIGNIFICANCE. This study shows that able-bodied individuals retain savings of split-belt adaptation over a three-week period, which indicates that only naïve split-belt walkers should be included in split-belt adaptation studies, as previous experience to split-belt walking will not be washed out, even after a prolonged period. In future research, these results can be compared with long-term savings in patient groups, to gain insight into factors underlying (un)successful gait training in rehabilitation

Forest Fires and Adaptation Options in Europe

This paper presents a quantitative assessment of adaptation options in the context of forest fires in Europe under projected climate change. A standalone fire model (SFM) based on a state-of-the-art large-scale forest fire modelling algorithm is used to explore fuel removal through prescribed burnings and improved fire suppression as adaptation options. The climate change projections are provided by three climate models reflecting the SRES A2 scenario. The SFM’s modelled burned areas for selected test countries in Europe show satisfying agreement with observed data coming from two different sources (European Forest Fire Information System and Global Fire Emissions Database). Our estimation of the potential increase in burned areas in Europe under ‘‘no adaptation’’ scenario is about 200 % by 2090 (compared with 2000–2008). The application of prescribed burnings has the potential to keep that increase below 50 %. Improvements in fire suppression might reduce this impact even further, e.g. boosting the probability of putting out a fire within a day by 10 % would result in about a 30 % decrease in annual burned areas. By taking more adaptation options into consideration, such as using agricultural fields as fire breaks, behavioural changes, and long-term options, burned areas can be potentially reduced further than projected in our analysis.JRC.H.7-Climate Risk Managemen

On the pion-nucleon coupling constant

In view of persisting misunderstanding about the determination of the pion-nucleon coupling constants in the Nijmegen multienergy partial-wave analyses of pp, np, and pbar-p scattering data, we present additional information which may clarify several points of discussion. We comment on several recent papers addressing the issue of the pion-nucleon coupling constant and criticizing the Nijmegen analyses.Comment: 19 pages, Nijmegen preprint THEF-NYM-92-0