One of the big challenges in Earth system science consists in providing reliable climate predictions on sub-seasonal, seasonal, decadal and longer timescales. The resulting data have the potential to be translated into climate information leading to a better assessment of multi-scale global and regional climate-related risks.
The latest developments and progress in climate forecasting on subseasonal-to-decadal timescales will be discussed and evaluated in this session. This will include presentations and discussions of predictions for a time horizon of up to ten years from dynamical ensemble and statistical/empirical forecast systems, as well as the aspects required for their application: forecast quality assessment, multi-model combination, bias adjustment, downscaling, etc.
Following the new WCPR strategic plan for 2019-2029, prediction enhancements are solicited from contributions embracing climate forecasting from an Earth system science perspective. This includes the study of coupled processes, impacts of coupling and feedbacks, and analysis/verification of the coupled atmosphere-ocean, atmosphere-land, atmosphere-hydrology, atmosphere-chemistry & aerosols, atmosphere-ice, ocean-hydrology, ocean-ice, ocean-chemistry and climate-biosphere (including human component). Contributions are also sought on initialization methods that optimally use observations from different Earth system components, on assessing and mitigating the impacts of model errors on skill, and on ensemble methods.
We also encourage contributions on the use of climate predictions for climate impact assessment, demonstrations of end-user value for climate risk applications and climate-change adaptation and the development of early warning systems.

A special focus will be put on the use of operational climate predictions (C3S, NMME, S2S), results from the CMIP5-CMIP6 decadal prediction experiments, and climate-prediction research and application projects (e.g. EUCP, APPLICATE, PREFACE, MIKLIP, MEDSCOPE, SECLI-FIRM, S2S4E).
An increasingly important aspect for climate forecast's applications is the use of most appropriate downscaling methods, based on dynamical or statistical approaches or their combination, that are needed to generate time series and fields with an appropriate spatial or temporal resolution. This is extensively considered in the session, which therefore brings together scientists from all geoscientific disciplines working on the prediction and application problems.

Predictions of climate from seasonal to decadal time scales and their applications will be discussed in this session. With a time horizon from a few months up to thirty years, such predictions are of major importance to society, and improving them presents an interesting scientific challenge. This session aims to embrace advances in our understanding of the origins of seasonal to decadal predictability, as well as in improving the respective forecast skill and making the most of this information by building and testing new applications and climate services.

The session will cover dynamical as well as statistical predictions, and their combination. It will investigate predictions of various climate phenomena, including extremes, from global to regional scales, and from seasonal to multidecadal time scales ("seamless prediction"). Physical processes relevant to long-term predictability sources (e.g. ocean, cryosphere, or land) as well as predicting large-scale atmospheric circulation anomalies associated to teleconnections will be discussed. Also, the time-dependence of the predictive skill (hindcast period) will be investigated. Analysis of predictions in a multi-model framework, and ensemble forecast initialization and generation, including innovative ensemble approaches to minimize initialization shocks, will be another focus of the session. The session will pay particular attention to innovative methods of quality assessment and verification of climate predictions, including extreme-weather frequencies, post-processing of climate hindcasts and forecasts, and quantification and interpretation of model uncertainty. We particularly invite contributions presenting the use of seasonal-to-decadal predictions for risk assessment, adaptation and further applications.

Information on the future climate is an essential basis for managing the risks, as well as potential opportunities, arising from a changing climate. Typically, this information comes from state-of-the-art numerical simulations of the climate in the form of climate predictions and climate projections. For many decision-makers and policymakers the information available from climate simulations is not at the appropriate spatial and temporal scales they need to form the basis for their climate-related risk assessments or for climate action plans. Also, some decision-makers require information that spans a range of time scales from a few months or a year ahead to decades into the future. Observational and emerging constraints can help evaluate and possibly constrain model-based uncertainty ranges.

This session aims to cover the advances in providing usable and reliable climate information for Europe over the next 40 or so years. It welcomes, without being restricted to, presentations on:

• Improved methods to quantify and understand uncertainty in climate predictions and projections for Europe. This could be on spatial scales from convectively resolving to global.
• Processes which bridge time scales from beyond a season to multiple decades and methodologies to blend the output from initialised predictions and non-initialised projections
• Demonstration of added value of initialised vs non-initialised near-term climate predictions and projections using innovative verification tools
• Illustration of the value of such climate information system through applications

The session will bring together research scientists and users from a range of projects including EUCP and national initiatives with the aim of sharing experiences, novel results and initiating discussions on this emerging topic.

Solicited speakers:
David Sexton (Met Office)
James Murphy (Met Office)
Carlo Buontempo (Copernicus Climate Change Service C3S)

Public information:
For a related Zoom session in parallel to the chat see: https://www.eucp-project.eu/eucp-updates/join-the-eucp-related-egu-session-bringing-together-future-climate-predictions-and-projections-for-europe/
https://zoom.us/j/94246127256?pwd=dWJpV1c4amtkWDhWMndFOW5hNk1sZz09
Meeting ID: 942 4612 7256
Password: 854513

Understanding the impact of climate change on natural and socio-economic outcomes plays an important role in informing a range of national and international policies, including energy, agriculture and health. Economic models of climate impacts used to guide policy rely on multiple components: projections of future climate change, damage functions, and policy responses, each of which comes with its own modelling challenges and uncertainties.

We invite research using process-based (e.g. Integrated Assessment Models) and empirical models of climate change to investigate future impacts, together with policy evaluation to explore effective mitigation, technology and adaptation pathways. Furthermore, we invite research on changes to, and new developments of climate-economic and econometric modelling.

Remaining carbon budgets specify the quantity of CO2 that can be emitted before a given warming level (such as the 1.5 °C target) is reached, and are thus of high interest to the public and policymakers. Yet, there are many sources of uncertainty which make it challenging to deduce this finite amount of CO2 emissions. The theoretical foundation of carbon budgets is based on the concept of the Transient Climate Response to cumulative CO2 Emissions (TCRE). This is the pathway-independent ratio of global warming per unit of cumulative CO2 emissions. However, accounting for non-CO2 forcings and changes in albedo or other Earth system feedbacks provides further challenges in calculating TCRE and the remaining carbon budgets.

This session aims to further our understanding of the climate response under different emission scenarios, and to advance our knowledge of associated carbon budgets consistent with meeting various levels of warming. We invite contributions that use a variety of tools, including fully coupled Earth System Models, Integrated Assessment Models, or simple climate model emulators. We welcome studies exploring different aspects related to carbon budgets and the TCRE framework, including: the governing mechanisms behind linearity of TCRE and its limitations, effects of different forcings and feedbacks (e.g. permafrost carbon feedback) and non-CO2 forcings (e.g. aerosols, and other non-CO2 greenhouse gases), estimates of the remaining carbon budget to reach a given temperature target (for example, the 1.5 °C warming level from the Paris Agreement), the role of pathway dependence, the climate-carbon responses to different emission scenarios (e.g. SSP scenarios, or idealized scenarios), and the behaviour of TCRE in response to artificial CO2 removal from the atmosphere (i.e. negative emissions). Contributions from the fields of climate policy and economics focused on applications of carbon budgets are also encouraged.

The world's energy, water, and land systems are in transition and rapidly integrating, driven by forces such as socioeconomic, demographic, climatic, and technological changes as well as policies intended to meet Sustainable Development Goals (SDGs) and other societal priorities. These dynamics weave across spatial scales, connecting global markets and trends to regional and sub-regional economies. At the same time, resources are often locally managed under varying administrative jurisdictions closely tied to inherent characteristics of each commodity such as river basins for water, grid regions for electricity and land-use boundaries for agriculture. Local decisions in turn are critical in deciding the aggregate success and consequences of national and global policies. Thus, there is a growing need to better characterize the energy-water-land nexus to guide robust and consistent decision making across these scales. This session invites abstracts exploring energy-water-land dynamics, trade patterns, policy interventions, infrastructure planning and uncertainty characterization across variable spatial boundaries.

Accurate and precise atmospheric measurements of greenhouse gas (GHG) concentrations reveal the rapid and unceasing rise of global GHG concentrations due to human activity. The resulting increases in global temperatures, sea-level, glacial retreat, and other negative impacts are clear. In response to this evidence, nations, states, and cities, private enterprises and individuals have been accelerating GHG reduction efforts while meeting the needs of global development. The urgency, complexity and economic implications of GHG reductions demand strategic investment in science-based information for planning and tracking emission reduction policies and actions. In response, the World Meteorological Organization (WMO) Global Atmosphere Watch Program (GAW) and its partners have initiated the development of an Integrated Global Greenhouse Gas Information System (IG3IS). IG3IS combines atmospheric GHG concentration measurements and human-activity data in an inverse modeling framework to help decision-makers take better-informed action to reduce emissions of greenhouse gases and pollutants that reduce air quality. This service is based on existing and successful measurement and analysis methods and use-cases for which the scientific and technical skill is proven or emerging.

This session intends to gather presentations from researchers and decision-makers (user-community) on the development, implementation and use of atmospheric measurement-based “top-down” and data-driven “bottom-up” GHG emission inventory estimates, and the combination of both approaches, explicit in space and time, to deliver actionable emissions information at scales where human activity occurs and emission reduction is most effective. This session will also showcase the new projects and efforts to develop “good-practice” standards under the World Meteorological Organization (WMO) Integrated Global Greenhouse Gas Information System (IG3IS), which is part of WMO’s commitment to science-based services.

Last year sessions ITS6.1-3 on urban geosciences have largely confirmed the urgency to develop inter-/trans-disciplinary approaches of urban geosciences to respond to the huge societal demand to radically improve urban systems and their interactions with their environment and climate. The session ITS.6.1 focussed on the need to develop holistic approaches going beyond specialised domains such as urban meteorology, hydrology, climatology, ecology and resilience to grasp the urban-geophysical systems in their multi-component and multiscale complexity. This in particular indispensable to resolve long lasting questions like multi-hazard threats and upscaling of climate solutions. The recent IPCC report 1.5°C confirms the necessity to fully take into account the multi-component complexity of the urban-geophysical systems to achieve the urban and infrastructure transition, one of the main four system transitions to be achieved

The present session calls therefore for contributions on the development transdisciplinary concepts, methodologies and tools, as well as their applications to urban-geophysical systems in view of this transition. Jean Jouzel (former IPCC vice-president) will open this session.

Public information:
ITS2.10 invites you to actively participate (audio and/or pdf slide sharing) to the Great Debate: "Epidemics, Urban Systems and Geosciences"
Monday 4 May, 12:30-14:00 ECT
e-room COVID-19 https://vmi270945.contaboserver.net/b/pau-guy-rwr
(no app to upload, just click on this link).

This debate is focused on a major upset of the geosciences agenda, particularly those dealing with urban systems so that they contribute more to well-being and health. This great debate will be an opportunity to take stock and open up perspectives, particularly on epidemics and mobility, the dynamics of Covid-19, cities, health and geosciences

Do not miss the opportunity to e-debate with:
Theo Geisel (Max Planck Institute, Göttingen)
Jacques Demongeot (Université Grenoble Alpes)
Mark J. Nieuwenhuijsen (Institute for Global Health, Barcelona)

This debate is a follow-up of ITS2.10 and is organised with the UNESCO UniTwin CS-DC (Complex Systems Digital Campus).

In an urbanizing world with major land-use changes, both human (social and economic) and natural systems and their environmental challenges and constraints need to be considered in order to achieve sustainable urban development. Nature‐based solutions (NBS) in urban areas can make anthropogenic landscapes more ecosystem-compatible, enhancing ecosystem services, preserving biodiversity, mitigating land degradation, and increasing urban resilience to environmental changes. Maintaining and restoring ecosystems and green–blue areas within urban regions is important for a) increasing the well‐being of urban populations, b) providing multifunctional services, such as storm water mitigation and local climate regulation, c) improving energy efficiency of buildings, and d) mitigating carbon emissions. Implementing NBS in urban areas is of growing importance worldwide, and particularly in the EU political agenda, as a way to attain some of the Sustainable Development Goals (e.g. Sustainable cities and communities), and to reinforce the New Urban Agenda. Implementing efficient NBS in urban landscapes requires integrated and interdisciplinary approaches.

This session aims to enhance the scientific basis for sustainable urban development and resilience and advance knowledge of innovative nature-based approaches to face environmental changes (e.g. in land use and climate) and simultaneously provide better understanding of associated social-ecological interactions. This session seeks to:

• Better understanding of advantages and disadvantages of NBS in Urban environments;
• New methods and tools to investigate the role of NBS in the context of environmental change, in particular the effectiveness of NBS in enhancing urban resilience;
• New insights and perspectives of NBS, particularly their role in providing urban ecosystem services, such as storm water regulation and reducing greenhouse gas emissions;
• Identifying opportunities for and barriers to implement NBS, driven by current regulatory frameworks and management practices - and how the former can be reaped and the latter overcome;
• Presenting overviews and case studies of NBS projects that also involve the private sector and market-based mechanisms;
• Interactions between NBS and the Sustainable Development Goals (SDGs);
• Approaches for integrating actors involved in landscape design and urban planning.

Land use and land cover change (LULCC), including land management, has the capacity to alter the climate by disrupting land-atmosphere fluxes of carbon, water and energy. Thus, there is a particular interest in understanding the role of LULCC as it relates to climate mitigation and adaptation strategies. Much attention has been devoted to the biogeochemical impacts of LULCC, yet there is an increasing awareness that the biogeophysical mechanisms (e.g. changes in surface properties such as albedo, roughness and evapotranspiration) should also be considered in climate change assessments of LULCC impacts on weather and climate. However, characterizing biogeophysical land-climate interactions remains challenging due to their complexity. If a cooling or a warming signal emerges depends on which of the biogeophysical processes dominates and on the size and pattern of the LULCC perturbation. Recent advances exploiting Earth system modelling and Earth observation tools are opening new possibilities to better describe LULCC and its effects at multiple temporal and spatial scales. This session invites studies that improve our general understanding of climate perturbations connected to LULCC from both biogeophysical and biogeochemical standpoints, and particularly those focusing on their intersection. This includes studies focusing on LULCC that can inform land-based climate mitigation and adaptation policies. Both observation-based and model-based analyses at local to global scales are welcome.

Groundwater is the world's most important, best protected and most exploited freshwater resource. It is intensively used by man. It is the prime source for drinking water supply and irrigation, hence critical to the global water-food-energy security nexus. But also for sustaining low flow requirements and ecological values of groundwater dependent ecosystems, the contribution by groundwater flow is essential. Groundwater therefore needs to be managed wisely, protected and especially used sustainably. These requirements are also expressed in Integrated Water Resources Management concepts, as e.g. in the European Water Framework Directive. In itself this is a challenge, however under a changing environment, climate, land use, population growth, etc., this task becomes a challenge especially in the light of limited data availability and consequential uncertainties. From arid over humid to arctic regions, in every type of climate changing environmental conditions become apparent and have very different local to regional hydrological effects.
In this session we invite contributions, which identify new consequences of a changing environment for future management, protection, and sustainable use of groundwater by applying integrative modelling, including water quantity and quality investigations as well as field observational studies. Methodologies, strategies, case studies as well as quantitative techniques for dealing with uncertainty and limited data availability are of interest for this session. We welcome studies describing how groundwater resources benefit from Integrated Water Resources Management approaches. Furthermore, contributions describing case studies and innovative techniques for adaptive management and protection of groundwater resources such as artificial recharge and conjunctive use are welcome.

Public information:
Dear audience of HS 8.2.2:
we decided to organize our session as zoom-meeting. Please join the Zoom-Meeting via:
https://tu-berlin.zoom.us/j/91545349950?pwd=aXZVMjhzWFlDcEtrWXArNkV0bGpRUT09
Meeting-ID: 915 4534 9950
Password: EGU
We are happy to welcome you!

A better understanding of the role of natural aerosols in the atmosphere is essential for assessing anthropogenic radiative forcing and the climate response. Our session explores primary aerosols and those formed from precursor gases emitted by natural sources, e.g. from wildfires, deserts, volcanoes and both the marine and terrestrial biosphere. The session intends to bring together experts from different fields to assess the state-of-the-science knowledge on natural aerosols and to identify future directions to reduce uncertainty. We encourage submissions that use models across different spatial scales and consider past, present or future perspectives, as well as measurements from remote sensing, field campaigns and laboratory experiments. Questions of particular interest are, but are not limited to: How can we distinguish between truly natural aerosols and those whose emissions or formation are influenced by anthropogenic activities? How have the contributions of natural aerosols to atmospheric composition and deposition changed over time? What are the consequences of these changes? Where are the missing links in our understanding of the lifecycle of natural aerosols in the atmosphere in the absence of anthropogenic influence? Can we identify any pristine environments in the present day that can help us understand the pre-industrial atmosphere?

The chemical composition of the middle atmosphere is not only relevant for understanding radiative forcing or protection of the biosphere from harmful UV radiation, but it also has an influence on tropospheric circulation and dynamics that act as a feedback on climate. Increasing greenhouse gases are expected to modify the large-scale circulation of the stratosphere, termed Brewer-Dobson circulation (BDC), and the chemical compositions of radiatively active gases, notably ozone and water vapour, in the upper troposphere and lower stratosphere (UTLS) region. Such changes in the BDC and UTLS composition are expected to change levels of surface UV radiation, modify the radiative forcing of climate, and feedback on the dynamics both within the stratosphere and at the surface. This session is particularly interested in evidence of the direct influence of climate change upon stratospheric dynamics and chemistry, as well as indirect feedbacks from these changes back upon surface climate. We welcome abstracts focused on stratospheric composition changes on time-scales encompassing inter-annual to centennial timescales,on local to global spatial scales, future projections from chemistry climate models, and discussing changes induced by both natural and anthropogenic factors, observations, as well as theoretical studies.