Climate and Weather Extremes

This paper provides a summary of the Workshop on Sub-Seasonal to Seasonal (S2S) Predictability of Extreme Weather and Climate, held at Columbia University, December 6–7, 2016. The 2-day workshop was attended by over 100 people and took stock of recent developments in Sub-seasonal to Seasonal predictability, S2S extreme weather phenomena, and real world predictions and use of forecasts. Workshop motivations, new findings, and outstanding questions discussed are described.

The translation speed of tropical cyclones has decreased globally by 10% over the past 70 years, compounding the increases in cyclone-related local rainfall that have resulted from anthropogenic warming.

In France, the 2016 winter wheat harvest was at its lowest since over 50 years. Here, Ben-Ari et al. show the role of seasonal temperature and precipitation extremes in this loss, and accounting for both of these variables explains large, historical yield loss events.

Extreme sea levels are a flood risk along the world’s coastlines. Here the authors carry out probabilistic projections of extreme sea levels and show that for the present century coastal flood hazards will increase significantly along most of the global coastlines.

Satellite observations and Earth system model simulations reveal that marine heatwaves have increased in recent decades and will increase further in terms of frequency, intensity, duration and spatial extent.

Storm runoff extremes dominate flash flood formation and generation, posing a grand threat to ecosystems and communities across the world. Here the authors show that current projected response of these storm runoff extremes to climate and anthropogenic changes are underestimated.

During 2002–2014, global mean temperatures stayed nearly steady, but both summertime warm and wintertime cold extreme temperature occurrences over North Hemisphere continents increased. Here the authors show that the contrasting changes in these metrics were driven by distinct climate patterns.