Storytelling is a powerful tool for supporting climate literacy. Media can reflect the changes that communities are already making and connect viewers to resources for participating in climate action. This summary provides a touch point for what is currently ongoing in Hollywood as a growing community of practice to include climate mitigation and adaptation information within scripted mainstream media, provide an overview of current challenges, and present suggestions for future work to integrate commercial media into the ecosystem of informal climate education. The new Climate Literacy Guide developed by the U.S. Global Change Research Program can help shape the next decade of storytelling as we build capacity for climate change communication.

A document by Shenyue Jia. Click on the document to view its contents.

A document by Hilary Chang. Click on the document to view its contents.

L'urbanisme tactique propose des approches de planification alternatives aux méthodes traditionnelles de conception urbaine. Axés sur la satisfaction des besoins des utilisateurs et la résolution des problèmes socio-urbains, ces projets utilisent des méthodes inclusives, intuitives, collaboratives, expérimentales et sensibles pour aborder la ville. Essentiellement, ces projets "ascendants" inspirent une nouvelle façon de penser la ville en construisant de nouvelles valeurs urbaines collectives. Cette analyse documentaire synthétise diverses perspectives sur l'urbanisme tactique, en explorant sa nature adaptative, son rôle de catalyseur économique, sa dimension d'autonomisation sociale, l'influence narrative des médias et son applicabilité à l'échelle mondiale. Collectivement, ces dimensions décrivent l'urbanisme tactique comme une force à multiples facettes qui façonne les aspects économiques, sociaux et culturels du développement urbain.

The marine cyanobacterium Trichodesmium has a remarkable ability to interact with and utilize air-borne dust as a nutrient source. However, dust may adversely affect Trichodesmium through buoyancy loss and exposure to toxic metals. Our study explored the effect of desert dust on buoyancy and mortality of natural Red Sea puff-shaped Trichodesmium thiebautii. Sinking velocities and ability of individual colonies to stay afloat with increasing dust loads were studied in sedimentation chambers. Low dust loads of up to ~400 ng per colony did not impact initial sinking velocity and colonies remained afloat in the chamber. Above this threshold, sinking velocity increased linearly with the colony dust load at a slope matching prediction based on Stoke’s law. The potential toxicity of dust was assessed with regards to metal dissolution kinetics, differentiating between rapidly released metals that may impact surface blooms and gradually released metals that may impact dust-centering colonies. Incubations with increasing dust concentrations revealed colony demise, but the observed lethal dose far exceeded dust concentrations measured in coastal and open ocean systems. Removal of toxic particles as a mechanism to reduce toxicity was explored using SEM-EDX imaging of colonies incubated with Cu-minerals, yet observations did not support this pathway. Combining our current and former experiments, we suggest that in natural settings the nutritional benefits gained by Trichodesmium via dust collection outweigh the risks of buoyancy loss and toxicity. Our data and concepts feed into the growing recognition of the significance of dust for Trichodesmium’s ecology and subsequently to ocean productivity.

Induced earthquakes are still highly unpredictable, and often caused by variations in pore fluid pressure. Monitoring and understanding the mechanisms of fluid-induced fault slip is essential for seismic risk mitigation and seismicity forecasting. Fluid-induced slip experiments were performed on critically stressed faulted sandstone samples, and the evolution of the actively sent ultrasonic waves throughout the experiment was measured. Two different fault types were used: smooth saw-cut fault samples at a 35º angle, and a rough fault created by in-situ faulting of the samples. Variations in the seismic slip velocity and friction along the fault plane were identified by the coda of the ultrasonic waves. Additionally, ultrasonic amplitudes show precursory signals to laboratory fault reactivation. Our results show that small and local variations in stress before fault failure can be inferred using coda wave interferometry for time-lapse monitoring, as coda waves are more sensitive to small perturbations in a medium than direct waves. Hence, these signals can be used as precursors to laboratory fault slip and to give insight into reactivation mechanisms. Our results show that time-lapse monitoring of coda waves can be used to monitor local stress changes associated with fault reactivation in this laboratory setting of fluid-induced fault reactivation. This is a critical first step towards a method for continuous monitoring of natural fault zones, contributing to seismic risk mitigation of induced and natural earthquakes.

Ionospheric heavy ions in the distant tail of the Earth’s magnetosphere at lunar distances are observed using the ARTEMIS mission. These heavy ions are originally produced in the terrestrial ionosphere. Using the ElectroStatic Analyzers (ESA) onboard the two probes orbiting the Moon, these heavy ions are observed as cold populations with distinct energies higher than the baseline energy of protons, with the energy-per-charge values for the heavy populations highly correlated with the proton energies. We conducted a full solar cycle survey of these heavy ion observations, including the flux, location, and drift energy, as well as the correlations with the solar wind and geomagnetic indices. The likelihood of finding these heavy ions in the preferred regions of observation called “loaded” quadrants of the terrestrial magnetotail is ~90%, regardless of the z orientation of the IMF. We characterize the ratio of the heavy ion energy to the proton energy, as well as the velocity ratio of these two populations, for events from 2010 to mid-2023. This study shows that the “common velocity” assumption for the proton and heavy ion particles, as suggested in previous work through the velocity filter effect, is not necessarily valid in this case. Challenges in the identification of the mass of the heavy ions due to the ESA’s lack of ion composition discrimination are addressed. It is proposed that at the lunar distances the heavy ion population mainly consists of atomic oxygen ions (O+) with velocities ~25% more than the velocity of the co-located proton population.

The linear cross correlation to quantify statistical connections or relationships finds wide applications in various geophysical and geodetic fields. However, there remains a dearth of comprehensive discourse regarding the significance testing for cross correlation, which would serve to differentiate statistically meaningful outcomes from those merely stemming from pure randomness. This study aims to develop a significance testing method for cross correlation in both white noise and red noise based on the -distribution within a rigorous statistical framework, which enables the establishment of significance tests for cross correlation as function of relative time shift within specified ranges, as demonstrated by Monte Carlo experiments that we perform. Via these results we critically examine the previously-claimed significant correlations between ENSO (El Niño Southern Oscillation ) and the global terrestrial water storage variations derived from the GRACE (Gravity Recovery and Climate Experiment ) satellite mission.

(Revised) The streamer to leader transition defines much of the physics of long sparks near atmospheric pressures. Streamer length is an important parameter in understanding lightning protection because of its link to step length and striking distance. While streamers are routinely observed in the lab, there have been only a few observations in the field. Fewer still are of natural flashes, and almost none have been observed much above sea-level.

One of the outstanding questions in lightning research is how dart leaders (also called recoil leaders or K-leaders) initiate and develop during a lightning flash. Dart leaders travel quickly (106-107 m/s) along previously ionized channels and occur intermittently in the later stage of a flash. We have recently reported some insights into dart leader initiation and development based on our BIMAP-3D observations. In this presentation we will expand on that work by combining observations and modeling to try to understand the observed dart leader behaviors. BIMAP-3D consists of two broadband interferometric mapping and polarization (BIMAP) systems that are separated by 11.5km at Los Alamos National Laboratory. Each station maps the lightning VHF sources in a 2D space, and the combination of the 2-station measurements provides a detailed 3D source map. A fast antenna is also included at each station for electric field change measurements. Our previously reported observations suggest dart leaders commonly exhibit an initial acceleration, followed by a more gradual deceleration to a stop. We also modeled the dart leader electric field change with a simple configuration of two point-charges, finding that the modeled tip charge increased in magnitude during the initial acceleration in some simple cases. We now employ a more sophisticated model to better understand the distribution of charge along the dart leader channel, and the background electric field in which the dart leader develops.Presented at the AGU 2023 Fall Meeting

A good understanding of the rupture patterns of small earthquakes is essential to understand the differences between earthquakes of different sizes. However, resolving the source complexity of small events (Mw<5) is challenging, because their seismic waveforms are distorted during propagation. In this study, we used high-quality seismic waveforms recorded by an excellent downhole sensor in Japan to directly examine the source complexities of 64 Mw3.3-5.0 short-range earthquakes (< 8 km). We found that even the waveforms of microearthquakes (Mw < 2) were simple at the sensor, indicating that the waveforms were scarcely disturbed by structural inhomogeneities. We inferred the moment rate functions from the shapes of the direct P-waves, which showed diversity in their complexity. Even conservatively estimated, 30% of the events had multiple subevents. The results suggest that methods that account for complexity, rather than those that assume a simple source pattern, are required to characterize even small earthquakes.

A document by Sebastian Uhlemann. Click on the document to view its contents.

A document by Filipi Vianna. Click on the document to view its contents.

The increase in computational power and richness of Earth system data has allowed new methods for simulating natural processes with higher precision and accuracy than previously imagined. Older methods to increase skill of computer model simulations include parameter inference, where the parameters of a forward simulation model are optimized to better represent reality and allow the model to capture dynamics seen in the observed data. However, these methods are limited by our physical understanding of the underlying system, making it impossible to capture certain dynamics when the model is under-represented. Machine learning methods have emerged as a potential tool to bypass the limitations of our physical understanding, and they can create simulations with much higher skill than previous methods. This work investigates and compares the skill of photosynthesis simulations from various model formulations including those with optimized parameters and those from machine learning.

Silverthorn, T.K. * and Richardson, J.S. Department of Forest and Conservation Sciences, The University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada* Corresponding authorEmail: [email protected]; [email protected] A version of the manuscript is published at: https://doi.org/10.1007/s10021-021-00621-z

Transformation of light to dense waters by atmospheric cooling is key to the Atlantic Meridional Overturning in the Subpolar Gyre. Convection in the center of the Irminger Gyre determines the transformation of the densest waters east of Greenland. We present a 19-year (2002-2020) weekly time series of hydrography and convection in the central Irminger Sea based on (bi-)daily mooring profiles supplemented with Argo profiles. A 70-year annual time series of shipboard hydrography shows that this mooring period is representative of longer term variability. The depth of convection varies strongly from winter to winter (288-1500 dbar), with a mean March climatogical mixed layer depth of 470 dbar and a mean maximum density reached of 27.70 ± 0.05 kg m-3. The densification of the water column by local convection directly impacts the sea surface height in the center of the Irminger Gyre and thus large-scale circulation patterns. Both the observations and a Price-Weller-Pinkel (PWP) mixed layer model analysis show that the main cause of interannual variability in mixed layer depth is the strength of the winter atmospheric surface forcing. Its role is three times as important as that of the strength of the maximum stratification in the preceeding summer. Strong stratification as a result of a fresh surface anomaly similar to the one observed in 2010 can weaken convection by approximately 170 m on average, but changes in surface forcing will need to be taken into account as well when considering the evolution of Irminger Sea convection under climate change.

Soil moisture is an important factor that affects terrestrial vegetation ecosystems and biological growth and development, and water deficit is one of the major environmental factors threatening vegetation restoration in the Loess Plateau. To determine the change in the soil water deficit characteristics from farmland to forestland on the Loess Plateau, in this study, we measured the soil water storage and deficit in abandoned grassland, shrubland, pioneer forestland and climax forestland along with vegetation succession. The results showed that the soil water content and the soil water storage with natural vegetation recovery from the abandoned grassland to shrubland and forestland showed a gradual declining trend, while on the contrary, the soil water deficit was increasing during succession, it was more severe in the deep soil than in the shallow soil layers, and the soil water deficit in July and September of the rainy season as well as that the vigorous growing period of plants was more serious than that in May and November, which are in the non-rainy season of the Chinese Loess Plateau. The vegetation types, soil texture and soil depth were the key factors affecting the soil water deficiency status in the process of vegetation succession. The results could have great potential in the sustainable development of forestry and provide a theoretical basis for effective water management and reasonable vegetation restoration in arid and semiarid loess regions.

Nutrient limitation is widespread in terrestrial ecosystems. Accordingly, representations of nitrogen (N) limitation in land models typically dampen rates of terrestrial carbon (C) accrual, compared with C-only simulations. These previous findings, however, rely on soil biogeochemical models that implicitly represent microbial activity and physiology. Here we present results from a biogeochemical model testbed that allows us to investigate how an explicit vs. implicit representation of soil microbial activity, as represented in the MIcrobial-MIneral Carbon Stabilization (MIMICS) and Carnegie–Ames–Stanford Approach (CASA) soil biogeochemical models, respectively, influence plant productivity and terrestrial C and N fluxes at initialization and over the historical period. When forced with common boundary conditions, larger soil C pools simulated by the MIMICS model reflect longer inferred soil organic matter (SOM) turnover times than those simulated by CASA. At steady state, terrestrial ecosystems experience greater N limitation when using the MIMICS-CN model, which also increases the inferred SOM turnover time. Over the historical period, however, higher rates of N mineralization were fueled by warming-induced acceleration of SOM decomposition over high latitude ecosystems in the MIMICS-CN simulation reduce this N limitation, resulting in faster rates of vegetation C accrual. Moreover, as SOM stoichiometry is an emergent property of MIMICS-CN, we highlight opportunities to deepen understanding of sources of persistent SOM and explore its potential sensitivity to environmental change. Our findings underscore the need to improve understanding and representation of plant and microbial resource allocation and competition in land models that represent coupled biogeochemical cycles under global change scenarios.