The need for carbon emissions-driven climate projections in CMIP7

Previous phases of the Coupled Model Intercomparison Project (CMIP) have primarily focused on simulations driven by atmospheric concentrations of greenhouse gases (GHGs), both for idealized model experiments, and for climate projections of different emissions scenarios. We argue that although this approach was pragmatic to allow parallel development of Earth System Model simulations and detailed socioeconomic futures, carbon cycle uncertainty as represented by diverse, process-resolving Earth System Models (ESMs) is not manifested in the scenario outcomes, thus omitting a dominant source of uncertainty in meeting the Paris Agreement. Mitigation policy is defined in terms of human activity (including emissions), with strategies varying in their timing of net-zero emissions, the balance of mitigation effort between short-lived and long-lived climate forcers, their reliance on land use strategy and the extent and timing of carbon removals. To explore the response to these drivers, ESMs need to explicitly represent complete cycles of major GHGs, including natural processes and anthropogenic influences. Carbon removal and sequestration strategies, which rely on proposed human management of natural systems, are currently represented upstream of ESMs in an idealized fashion during scenario development. However, proper accounting of the coupled system impacts of and feedback on such interventions requires explicit process representation in ESMs to build self-consistent physical representations of their potential effectiveness and risks under climate change. We propose that CMIP7 efforts prioritize simulations driven by CO2 emissions from fossil fuel use, projected deployment of carbon dioxide removal technologies, as well as land use and management, using the process resolution allowed by state-of-the-art ESMs to resolve carbon-climate feedbacks. Post-CMIP7 ambitions should aim to incorporate modeling of non-CO2 GHGs (in particular sources and sinks of methane) and process-based representation of carbon removal options. Such experiments would allow resources to be allocated to policy-relevant climate projections and better real-time information related to the detectability and verification of emissions reductions and their relationship to expected near-term climate impacts. Such efforts will provide information on the range of possible future climate states including Earth system processes and feedbacks which are increasingly well-represented in ESMs, thus forming a critical and complementary pillar underpinning proposed km-scale climate modeling activities and calls to better utilize novel machine learning approaches

Distance decay and directional diffusion of ecoclimate teleconnections driven by regional-scale tree die-off

Climate change is triggering regional-scale alterations in vegetation including land cover change such as forest die-off. At sufficient magnitudes, land cover change from forest die-off in one region can change not only local climate but also vegetation including agriculture elsewhere via changes in larger scale climate patterns, termed an ‘ecoclimate teleconnection’. Ecoclimate teleconnections can therefore have impacts on vegetative growth in distant regions, but the degrees to which the impact decays with distance or directionally diffuses relative to the initial perturbation are general properties that have not been evaluated. We used the Community Earth system model to study this, examining the implications of tree die-off in 14 major US forested regions. For each case we evaluated the ecological impact across North America as a function of distance and direction from the location of regional tree die-off. We found that the effects on gross primary productivity (GPP) generally decayed linearly with distance, with notable exceptions. Distance from the region of tree die-off alone explained up to ∼30% of the variance in many regions. We also found that the GPP impact was not uniform across directions and that including an additional term to account for direction to regional land cover change from tree die-off was statistically significant for nearly all regions and explained up to ∼40% of the variance in many regions, comparable in magnitude to the influence of El Nino on GPP in the Western US. Our results provide novel insights into the generality of distance decay and directional diffusion of ecoclimate teleconnections, and suggest that it may be hard to identify expected impacts of tree die-off without case-specific simulations. Such patterns of distance decay, directional diffusion, and their exceptions are relevant for cross-regional policy that links forests and other agriculture (e.g. US Department of Agriculture). © 2023 The Author(s). Published by IOP Publishing Ltd.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Nous les arbres : catalogue de l'exposition

Nous les Arbres : Exposition , Paris , FRA, 12-/07/2019 - 10/11/2019L'exposition fait entendre les voix multiples d'une communauté d'artistes, de botanistes et de philosophes qui ont développé, à travers un parcours esthétique ou scientifique unique, un lien puissant et intime avec les arbres, mettant ainsi en lumière toute la beauté et la complexité biologique de ces grands protagonistes du monde vivant aujourd'hui menacés. Les arbres - comme l'ensemble du règne végétal - ont fait l'objet, ces dernières décennies de découvertes scientifiques qui permettent de porter un nouveau regard sur ces vénérables membres de la communauté des vivants. Capacités sensorielles, aptitude à la communication, développement d'une mémoire, symbiose avec d'autres espèces et influence sur le climat : la révélation de ces facultés invite à émettre l'hypothèse fascinante d'une "intelligence végétale" qui pourrait apporter des éléments de réponse à bien des défis environnementaux actuels. En résonance avec cette "révolution végétale", l'exposition Nous les Arbres croise les réflexions d'artistes et de chercheurs qui prolongent l'exploration des questions écologiques et de la place de l'homme au sein du monde vivant. Mettant en regard les oeuvres d'artistes d'Amérique latine, d'Europe, des États-Unis, mais également d'Iran, ou encore issus de communautés indigènes comme les Nivaclé et les Guaraní, au Paraguay, ainsi que les Indiens Yanomami en Amazonie brésilienne, le parcours de l'exposition déroule trois fils narratifs : celui de la connaissance des arbres - de la botanique à la nouvelle biologie végétale - ; celui de leur esthétique - de la contemplation naturaliste à la transposition onirique - ; celui enfin de leur dévastation - du constat documentaire au témoignage artistique