A5023325806- Climate variability and models
- Meteorological Phenomena and Simulations
- Atmospheric and Environmental Gas Dynamics
- Cryospheric studies and observations
- Geology and Paleoclimatology Research
- Hydrology and Watershed Management Studies
- Tree-ring climate responses
- Hydrology and Drought Analysis
- Climate change impacts on agriculture
- Climate Change Policy and Economics
- Climate change and permafrost
- Arctic and Antarctic ice dynamics
- Flood Risk Assessment and Management
- Plant Water Relations and Carbon Dynamics
- Water resources management and optimization
- Geophysics and Gravity Measurements
- Tropical and Extratropical Cyclones Research
- Oceanographic and Atmospheric Processes
- Fire effects on ecosystems
- Geological Studies and Exploration
- Energy Load and Power Forecasting
- Atmospheric chemistry and aerosols
- Hydrological Forecasting Using AI
- Climate Change and Health Impacts
- demographic modeling and climate adaptation
Cornell University
2020-2025
NSF NCAR Climate and Global Dynamics Laboratory
2016-2025
NSF National Center for Atmospheric Research
2016-2025
Pacific Northwest National Laboratory
2024
U.S. National Science Foundation
2024
Hollister (United States)
2023
ETH Zurich
2020-2022
Research Applications (United States)
2017-2018
Oeschger Centre for Climate Change Research
2011-2016
University of Bern
2011-2016
Strong future warming in some new climate models is less likely as their recent inconsistent with observed trends.
Understanding changes in precipitation variability is essential for a complete explanation of the hydrologic cycle's response to warming and its impacts. While mean extreme have been studied intensively, has received less attention, despite theoretical practical importance. Here, we show that most climate models increases over majority global land area (66% robust increase seasonal-mean precipitation). Comparing recent decades RCP8.5 projections end 21st century, find global, multi-model...
Partitioning uncertainty in projections of future climate change into contributions from internal variability, model response and emissions scenarios has historically relied on making assumptions about forced changes the mean variability. With advent multiple single-model initial-condition large ensembles (SMILEs), these can be scrutinized, as they allow a more robust separation between sources uncertainty. Here, framework Hawkins Sutton (2009) for partitioning is revisited temperature...
Abstract. Disastrous bushfires during the last months of 2019 and January 2020 affected Australia, raising question to what extent risk these fires was exacerbated by anthropogenic climate change. To answer for southeastern where were particularly severe, affecting people ecosystems, we use a physically based index fire weather, Fire Weather Index; long-term observations heat drought; 11 large ensembles state-of-the-art models. We find trends in Index fifth-generation European Centre...
Abstract. The sixth Coupled Model Intercomparison Project (CMIP6) constitutes the latest update on expected future climate change based a new generation of models. To extract reliable estimates warming and related uncertainties from these models, spread in their projections is often translated into probabilistic such as mean likely range. Here, we use model weighting approach, which accounts for models' historical performance several diagnostics well interdependence within CMIP6 ensemble, to...
Abstract The large socioeconomic costs of droughts make them a crucial target for impact assessments climate change scenarios. Using multiple drought metrics and set simulations with the Community Earth System Model targeting 1.5°C 2°C above preindustrial global mean temperatures, we investigate changes in aridity risk consecutive years. If warming is limited to 2°C, these suggest little U.S. Southwest Central Plains compared present day. In Mediterranean central Europe, however, increases...
Abstract. Towards the end of June 2021, temperature records were broken by several degrees Celsius in cities Pacific Northwest areas US and Canada, leading to spikes sudden deaths sharp increases emergency calls hospital visits for heat-related illnesses. Here we present a multi-model, multi-method attribution analysis investigate extent which human-induced climate change has influenced probability intensity extreme heat waves this region. Based on observations, modelling classical...
Compound hot–dry events—co-occurring hot and dry extremes—frequently cause damages to human natural systems, often exceeding separate impacts from heatwaves droughts. Strong increases in the occurrence of these events are projected with warming, but associated uncertainties remain large poorly understood. Here, using climate model ensembles, we show that mean precipitation trends exclusively modulate future compound over land. This occurs because local warming will be enough droughts always...
Abstract. The Paris Agreement of December 2015 stated a goal to pursue efforts keep global temperatures below 1.5 °C above preindustrial levels and well 2 °C. IPCC was charged with assessing climate impacts at these temperature levels, but fully coupled equilibrium simulations do not currently exist inform such assessments. In this study, we produce set scenarios using simple model designed achieve long-term in stable climate. These are then used century-scale ensemble the Community Earth...
In the period 2015–2017, Western Cape region has suffered from three consecutive years of below average rainfall—leading to a prolonged drought and acute water shortages, most prominently in city Town. After testing that precipitation deficit is primary driver behind reduced surface availability, we undertake multi-method attribution analysis for meteorological drought, defined terms 3 running mean averaged over area. The exact estimate return time event sensitive number stations whose data...
The changing global climate is producing increasingly unusual weather relative to preindustrial conditions. In an absolute sense, these conditions constitute direct evidence of anthropogenic change. However, human evaluation as either normal or abnormal will also be influenced by a range factors including expectations, memory limitations, and cognitive biases. Here we show that experience in recent years-rather than longer historical periods-determines the climatic baseline against which...
Abstract The evolving roles of anthropogenic aerosols (AER) and greenhouse gases (GHG) in driving large-scale patterns precipitation SST trends during 1920–2080 are studied using a new set “all-but-one-forcing” initial-condition large ensembles (LEs) with the Community Earth System Model version 1 (CESM1), which complement original “all-forcing” CESM1 LE (ALL). number ensemble members (15–20) each LEs enables regional impacts AER GHG to be isolated from noise model’s internal variability....
Over the first half of 2020, Siberia experienced warmest period from January to June since records began and on 20th weather station at Verkhoyansk reported 38 °C, highest daily maximum temperature recorded north Arctic Circle. We present a multi-model, multi-method analysis how anthropogenic climate change affected probability these events occurring using both observational datasets large collection models, including state-of-the-art higher-resolution simulations designed for attribution...
Attribution studies have identified a robust anthropogenic fingerprint in increased 21st century wildfire risk. However, the risks associated with individual aspects of aerosol and greenhouse gases (GHG) emissions, biomass burning land use/land cover change remain unknown. Here, we use new climate model large ensembles isolating these influences to show that GHG-driven increases extreme fire weather conditions been balanced by aerosol-driven cooling throughout 20th century. This compensation...
Abstract. Towards the end of June 2021, temperature records were broken by several degrees Celsius in cities Pacific northwest areas U.S. and Canada, leading to spikes sudden deaths, sharp increases hospital visits for heat-related illnesses emergency calls. Here we present a multi-model, multi-method attribution analysis investigate what extent human-induced climate change has influenced probability intensity extreme heatwaves this region. Based on observations modeling, occurrence heatwave...
SignificanceTwenty-first century trends in hydroclimate are so large that future average conditions will, most cases, fall into the range of what we would today consider extreme drought or pluvial states. Using climate model ensembles, remove background trend and find risk droughts pluvials relative to (changing) baseline is fairly similar 20th risk. By continually adapting long-term changes, these risks could therefore perhaps be minimized. However, increases frequency extremely wet dry...
Societally relevant weather impacts typically result from compound events, which are rare combinations of and climate drivers. Focussing on four event types arising different variables across space time, here we illustrate that robust analyses events - such as frequency uncertainty analysis under present-day future conditions, attribution to change, exploration low-probability-high-impact require data with very large sample size. In particular, the required is much larger than needed for...
Arid and semi-arid regions of the world are particularly vulnerable to greenhouse gas–driven hydroclimate change. Climate models our primary tool for projecting future that society in these must adapt to, but here, we present a concerning discrepancy between observed model-based historical trends. Over arid/semi-arid world, predominant signal all model simulations is an increase atmospheric water vapor, on average, over last four decades, association with increased vapor–holding capacity...
Abstract Adaptation to climate change has now become a necessity for many regions. Yet, adaptation planning at regional scales over the next few decades is challenging given contingencies originating from combination of different sources projection uncertainty, chief among them internal variability. Here, we review causes and consequences variability, how it can be quantified accounted in uncertainty assessments, what research questions remain most pertinent better understand its predictive...