2022

1. [One Health High-Level Expert Panel (OHHLEP) et al. 2022] One Health and Climate Change. See also [Dar et al. 2022]
   OneHealth, Climate Change

2. [McKay et al. 2022] Abstract: Climate tipping points occur when change in a part of the climate system becomes self-perpetuating beyond a warming threshold, leading to substantial Earth system impacts. Synthesizing paleoclimate, observational, and model-based studies, we provide a revised shortlist of global “core” tipping elements and regional “impact” tipping elements and their temperature thresholds. Current global warming of 1.1°C above preindustrial temperatures already lies within the lower end of some tipping point uncertainty ranges. Several tipping points may be triggered in the Paris Agreement range of 1.5 to <2°C global warming, with many more likely at the 2 to 3°C of warming expected on current policy trajectories. This strengthens the evidence base for urgent action to mitigate climate change and to develop improved tipping point risk assessment, early warning capability, and adaptation strategies. Climate tipping points are conditions beyond which changes in a part of the climate system become self-perpetuating. These changes may lead to abrupt, irreversible, and dangerous impacts with serious implications for humanity. Armstrong McKay et al. present an updated assessment of the most important climate tipping elements and their potential tipping points, including their temperature thresholds, time scales, and impacts. Their analysis indicates that even global warming of 1°C, a threshold that we already have passed, puts us at risk by triggering some tipping points. This finding provides a compelling reason to limit additional warming as much as possible. —HJS Global warming greater than 1.5°C could trigger multiple climate tipping points.
   1.5 warming and tipping points

3. [Degroot et al. 2022] Recent decades have seen the rapid expansion of scholarship that identifies societal responses to past climatic fluctuations. This fast-changing scholarship, which was recently synthesized as the History of Climate and Society (HCS), is today undertaken primary by archaeologists, economists, geneticists, geographers, historians and paleoclimatologists. This review is the first to consider how scholars in all of these disciplines approach HCS studies. It begins by explaining how climatic changes and anomalies are reconstructed by paleoclimatologists and historical climatologists. It then provides a broad overview of major changes and anomalies over the 300,000-year history of Homo sapiens, explaining both the causes and environmental consequences of these fluctuations. Next, it introduces the sources, methods, and models employed by scholars in major HCS disciplines. It continues by describing the debates, themes, and findings of HCS scholarship in its major disciplines, and then outlines the potential of transdisciplinary, ‘consilient’ approaches to the field. It concludes by explaining how HCS studies can inform policy and activism that confronts anthropogenic global warming.
   HCS, History of Climate and Society

4. [Halifa-Marín1 et al. 2022] Abstract. Although the literature still debates how several anthropogenic and natural factors have contributed to the re- cent streamflow decline in the Iberian Peninsula, a continu- ing decrease in winter precipitation (WP) has been noticed in this area since the 1980s and has been associated with large- scale atmospheric drivers. This contribution assesses the po- tential propagation of this WP deficit into water resource variability. For this purpose, the novel “NEar-Natural Water Inflows to REservoirs of Spain” (NENWIRES) dataset was created. The results highlight that higher decreases in winter water inflows (WWIs) are always related to WP reductions. However, while the decline in WP was strongly provoked by the enhancement of the North Atlantic Oscillation index (NAOi) during the study period, WWI reductions could not be essentially linked to the NAOi behaviour in several NEN- WIRES catchments. Instead, the intensification of drought conditions and forest extension promoted WWI decreases over the target area and aided in understanding why WWI reductions were generally higher than WP decreases. In sum- mary, most humid catchments registered a WWI decline that was mainly promoted by NAOi enhancement, whereas the extension of forest and evapotranspiration increases seem to explain WWI losses in semi-arid environments. This contri- bution sheds light on the recent debate regarding the mag- nitude and drivers of water resource decline over southern European regions.
   Water resources Iberia

5. [Touza and Francés 2022a] Abstract. Structural economic reform is needed on an unprecedented scale and at an unprecedented rate to avert the worst impacts of climate change. Drawing on the lessons learned from Roosevelt’s New Deal, the paper analyses the extent to which green deal proposals and recovery plans put forth this century can deliver climate-resilient development according to a green growth (ecomodernisation) perspective. The paper concludes that while some greening of laws and post- crisis stimulus packages has been observed, it cannot be unequivocally concluded that pro-growth green deals can deliver a just net-zero and just transition.
   Economia y cambio climático. New Deal, green fiscal stimulus, green New Deal, ecomodernisation, degrowth.

6. [Touza and Francés 2022b] Resumen: Las políticas de energía y clima adoptadas por la UE desde los años ochenta del siglo XX han sentado las bases para proponer el ob- jetivo de alcanzar la neutralidad climática en 2050, alineando intereses y valores de la Unión y reforzando su posición de líder me- diante el ejemplo en el ámbito internacional. Para alcanzar dicho objetivo, se presenta en 2019 el Pacto Verde Europeo (PVE) al que acompaña en 2021 el paquete «Objetivo 55» que incluye numerosas medidas legislativas y ejecutivas, revisiones de medidas preexisten- tes y nuevos fondos que tratan de limitar el impacto de la descarbonización en los más vulnerables. Guiada por el PVE, la UE enfren- taba la pandemia con el mayor paquete de re- cuperación verde de su historia, que se espera facilite el cumplimiento de los objetivos de los Planes Nacionales Integrados de Energía y Clima. Más recientemente, la respuesta de la UE a la invasión rusa de Ucrania, con REPowerEU, aumenta la ambición renovable de manera muy significativa. Todo ello en un contexto de incertidumbre radical y deterioro de las expectativas económicas. Así, algu- nos de los retos a los que se enfrenta la UE para cumplir con sus objetivos de descarbo- nización incluyen: asegurar la seguridad del suministro, diversificar fuentes energéticas y proveedores, reducir la dependencia energé- tica de Rusia, adaptarse a la volatilidad de los precios de la energía y asegurar la aceptación de las políticas de descarbonización.
   Economia y cambio climático. cambio climático, política climática, política energética, Pacto Verde Europeo, Fit for 55.

7. [Lam et al. 2022] We introduce a machine-learning (ML)-based weather simulator—called “GraphCast”—which outper- forms the most accurate deterministic operational medium-range weather forecasting system in the world, as well as all previous ML baselines. GraphCast is an autoregressive model, based on graph neural networks and a novel high-resolution multi-scale mesh representation, which we trained on his- torical weather data from the European Centre for Medium-Range Weather Forecasts (ECMWF)’s ERA5 reanalysis archive. It can make 10-day forecasts, at 6-hour time intervals, of five surface variables and six atmospheric variables, each at 37 vertical pressure levels, on a 0.25° latitude-longitude grid, which corresponds to roughly 25 × 25 kilometer resolution at the equator. Our results show GraphCast is more accurate than ECMWF’s deterministic operational forecasting system, HRES, on 90.0% of the 2760 vari- able and lead time combinations we evaluated. GraphCast also outperforms the most accurate previous ML-based weather forecasting model on 99.2% of the 252 targets it reported. GraphCast can generate a 10-day forecast (35 gigabytes of data) in under 60 seconds on Cloud TPU v4 hardware. Unlike tradi- tional forecasting methods, ML-based forecasting scales well with data: by training on bigger, higher quality, and more recent data, the skill of the forecasts can improve. Together these results represent a key step forward in complementing and improving weather modeling with ML, open new opportuni- ties for fast, accurate forecasting, and help realize the promise of ML-based simulation in the physical sciences.
   Short term forecasting based on artificial intelligence

8. [Mazón et al. 2022] Abstract. One of the most important challenges our global civilization faces in the coming years is to achieve the Paris Agreement’s goals of preventing the planet’s temperature from exceeding the pre-industrial values of 2◦C and limiting it, at most, to 1.5◦C. Awareness of this problem has led to the creation of many national and international organizations in recent decades, with many thematic conferences being held and new policies to reduce greenhouse gas emissions—so far without attaining the necessary success. Among the political measures taken in recent years is the climate emergency declaration issued by many government institutions, highlighting the serious and urgent problem of climate change and the imperative need to find a solution. The COVID-19 pandemic, has led to reductions in CO2 emissions due to the substantial decreases in economic activity incurred by several countries imposing non-pharmaceutical interventions. Thus, the current practice of declaring a climate emergency must be fortified by making it a legal tool in order to reduce CO2 emissions and reach the objectives set by the Paris Agreement. Yet, what should this climate emergency declaration look like? In considering these current COVID-19-induced reductions in CO2 emissions, we hereby propose a political plan for stopping emissions to try to achieve the objectives of the Paris Agreement and at least some of the UN’s 2030 Sustainable Development Goals. The article also proposes how to define the global climate alarm declaration to serve as an international legal tool for reducing CO2 and transitioning to a world free of these massive emissions. By analyzing the reduction of the emissions in different scenarios based on the COVID-19 pandemic, the article shows that the needed reduction of emissions proposed by the EU in 2030 cannot be reached in any of the scenarios limiting the CO2 emissions.
   Feasibility of CO2 reductions towards zero emissions

9. [Martin et al. 2022] 10 insights climate science for cop27. Also [FUT 2022]
   cop, impacts of c. change

10. [Rousi et al. 2022] Abstract: Persistent heat extremes can have severe impacts on ecosystems and societies, including excess mortality, wildfires, and harvest failures. Here we identify Europe as a heatwave hotspot, exhibiting upward trends that are three-to-four times faster compared to the rest of the northern midlatitudes over the past 42 years. This accelerated trend is linked to atmo- spheric dynamical changes via an increase in the frequency and persistence of double jet stream states over Eurasia. We find that double jet occurrences are particularly important for western European heatwaves, explaining up to 35% of temperature variability. The upward trend in the persistence of double jet events explains almost all of the accelerated heatwave trend in western Europe, and about 30% of it over the extended European region. Those findings provide evidence that in addition to thermodynamical drivers, atmospheric dynamical changes have contributed to the increased rate of European heatwaves, with implications for risk management and potential adaptation strategies.
    Heat Waves Europe

11. [Slingo et al. 2022] Abstract. Current global climate models struggle to represent precipitation and related extreme events, with serious implications for the physical evidence base to support climate actions. A leap to kilometre-scale models could overcome this shortcoming but requires collaboration on an unprecedented scale.
    High resolution ESM, MCS

12. [Steinman et al. 2022] Abstract. Uncertainty about the influence of anthropogenic radiative forcing on the position and strength of convective rainfall in the Intertropical Convergence Zone (ITCZ) inhibits our ability to project future tropical hydroclimate change in a warmer world. Paleoclimatic and modeling data inform on the timescales and mechanisms of ITCZ variability; yet a comprehensive, long-term perspective remains elusive. Here, we quantify the evolution of neotropical hydroclimate over the preindustrial past millennium (850 to 1850 CE) using a synthesis of 48 paleo-records, accounting for uncertainties in paleo-archive age models. We show that an interhemispheric pattern of precipitation antiphasing occurred on multicentury timescales in response to changes in natural radiative forcing. The conventionally defined “Little Ice Age” (1450 to 1850 CE) was marked by a clear shift toward wetter conditions in the southern neotropics and a less distinct and spatiotemporally complex transition toward drier conditions in the northern neotropics. This pattern of hydroclimatic change is consistent with results from climate model simulations indicating that a relative cooling of the Northern Hemisphere caused a southward shift in the thermal equator across the Atlantic basin and a southerly displacement of the ITCZ in the tropical Americas, with volcanic forcing as the principal driver. These findings are at odds with proxy-based reconstructions of ITCZ behavior in the western Pacific basin, where changes in ITCZ width and intensity, rather than mean position, appear to have driven hydroclimate transitions over the last millennium. This reinforces the idea that ITCZ responses to external forcing are region specific, complicating projections of the tropical precipitation response to global warming.
    Interhemispheric drought changes last millennium

13. [von Storch 2022] Abstract. The middle class needs concerns, needs to fend off real or perceived threats, as part of life. When no other immediate and direct threats, such as war, hunger, or viruses, are present, environmental deterioration is a well-received issue by the middle class, which allows for the development and practice to show their good intentions. Unfortunately, these intentions are not always well guided, their measurable effects in terms of, for instance, limiting greenhouse gas emissions (and thus climate change) are often negligible. Here, it is suggested to embark on “Apollo projects”, which bundle the potential and willingness of the middle class. These projects should develop specific technologies, which are economically attractive and will therefore spread throughout the world, and will therefore allow for a reduction of greenhouse gas emissions in the gigaton-range. Such pan-national projects could address emission-free ship- or air-propulsion, the electrification of heating or that of processes in the chemical industry.
    Climate of the middle class