Calibrated and Systematic Characterization, Attribution, and Detection of Extremes (CASCADE)

Climate extremes are considered to be one of the most stressing forms of climate change by the IPCC. The risks to society and the natural environment are magnified when multiple types of extremes are coincident and collocated, e.g., simultaneous droughts and heat waves, downpours and storm surges (e.g., both caused by atmospheric rivers) in coastal zones, and other potentially destructive combinations of extreme weather events. We propose to label these phenomena as compound extremes. At present, however, the theory of extreme values that underpins much of the existing analysis of simulations and observations has been formulated for characterization of univariate phenomena, for example just drought severity, rather than that of multi-variate phenomena, for example coincident droughts and heat waves. Conventional extreme value theory is therefore unsuitable for quantifying the properties, in particular the magnitudes and return frequencies, of compound extremes. It is also unsuitable for quantifying the increasing risks of multi-sectoral impacts arising from changes in the frequency and severity of compound extremes in a warmer climate.

Three, five, and ten-year plan: We will develop the necessary theory for multi-variate extremes that will reduce to the classical Generalized Extreme Value (GEV) theory widely used to study these phenomena in the limit of a single variable. The conceptual breakthroughs and theoretical derivations required are already well underway with university colleagues. The longer-term challenge after the development of the statistical theory is learning how to interpret the multi-dimensional space of extremes in the context of impacts.

Publications:

A basis set for exploration of sensitivity to prescribed ocean conditions for estimating human contributions to extreme weather in CAM5.1-1degree
A Probabilistic Gridded Product for Daily Precipitation Extremes Over the United States
An Evaluation of the Consistency of Extremes in Gridded Precipitation Data Sets
Anthropogenic Influences on Major Tropical Cyclone Events
Attributable Human-Induced Changes in the Likelihood and Magnitude of the Observed Extreme Precipitation during Hurricane Harvey
Changes in Extremely Hot Days Under Stabilized 1.5C and 2.0C Global Warming Scenarios as Simulated by the HAPPI Multi-Model Ensemble
Changes in Tropical Cyclones Under Stabilized 1.5 °C and 2.0 °C Global Warming Scenarios as Simulated by the Community Atmospheric Model Under the HAPPI Protocols
Diversity of ENSO Events Unified by Convective Threshold Sea Surface Temperature: A Nonlinear ENSO Index
Early 21st Century Anthropogenic Changes in Extremely Hot Days as Simulated by the C20C+ Detection and Attribution Multi-Model Ensemble
Estimating the Human Influence on Tropical Cyclone Intensity as the Climate Changes
Prognostic Power of Extreme Rainfall Scaling Formulas Across Space and Time Scales
Quantifying Statistical Uncertainty in the Attribution of Human Influence on Severe Weather
Simulation and Analysis of Hurricane-Driven Extreme Wave Climate Under Two Ocean Warming Scenarios
Spatially-Dependent Multiple Testing Under Model Misspecification, With Application to Detection of Anthropogenic Influence on Extreme Climate Events
The Benefits of Global High-Resolution for Climate Simulation: Process-Understanding and the Enabling of Stakeholder Decisions at the Regional Scale
The Influence of ENSO Flavors on Western North Pacific Tropical Cyclone Activity
The Response of Atlantic Tropical Cyclones to Suppression of African Easterly Waves

Research Highlights:

A Basis Set for Exploration of Sensitivity to Prescribed Ocean Conditions for Estimating Human Contributions to Extreme Weather in CAM5.1-1degree Highlight Presentation
A Probabilistic Gridded Product for Daily Precipitation Extremes Over the United States Highlight Presentation
An Evaluation of the Consistency of Extremes in Gridded Precipitation Data Sets Highlight Presentation
Anthropogenic Influences on Major Tropical Cyclone Events Highlight Presentation
Attributable Human‐Induced Changes in the Likelihood and Magnitude of the Observed Extreme Precipitation during Hurricane Harvey Highlight Presentation
Changes in Extremely Hot Days Under Stabilized 1.5oC and 2.0oC Global Warming Scenarios as Simulated by the HAPPI Multi-Model Ensemble Highlight Presentation
Changes in Tropical Cyclones Under Stabilized 1.5oC and 2.0oC Global Warming Scenarios as Simulated by the Community Atmospheric Model under the HAPPI Protocols Highlight Presentation
Diversity of ENSO Events Unified by Convective Threshold Sea Surface Temperature: A Nonlinear ENSO Index Highlight Presentation
Early 21st Century Anthropogenic Changes in Extremely Hot Days as Simulated by the C20C+ Detection and Attribution Multi-Model Ensemble Highlight Presentation
Estimating the Human Influence on Tropical Cyclone Intensity as the Climate Changes Highlight Presentation
Evaluating and Improving Statistical Methods Used in Assessing Human Influence on Severe Weather Highlight Presentation
Prognostic Power of Extreme Rainfall Scaling Formulas Across Space and Time Scales Highlight Presentation
Simulation and Analysis of Hurricane-Driven Extreme Wave Climate Under Two Ocean Warming Scenarios Highlight Presentation
Spatially-Dependent Multiple Testing Under Model Misspecification, With Application to Detection of Anthropogenic Influence on Extreme Climate Events Highlight Presentation
The Benefits of Global High-Resolution for Climate Simulation: Process-Understanding and the Enabling of Stakeholder Decisions at the Regional Scale Highlight Presentation
The Influence of ENSO Flavors on Western North Pacific Tropical Cyclone Activity Highlight Presentation
The Response of Atlantic Tropical Cyclones to Suppression of African Easterly Waves Highlight Presentation