A next-generation modeling system supports assessment of changing climate risks.

NOAA, the USGS, and Princeton University scientists contributed to the development of a new modeling system for seasonal-to-multidecadal climate predictions and projections, SPEAR (Seamless System for Prediction and Earth System Research), at NOAA’s Geophysical Fluid Dynamics Laboratory.^[1] SPEAR combines a set of newly developed components that simulate the ocean, atmosphere, land, sea ice, and their interactions. The new system is used for real-time seasonal climate predictions as part of the North American Multimodel Ensemble, as well as for decadal predictions as part of a World Meteorological Organization international effort.

In making predictions, SPEAR uses a wide range of observed atmospheric and oceanic data for initial conditions to start the predictions, in combination with a new data assimilation system. SPEAR has reduced error and increased accuracy for seasonal predictions, providing increasingly useful information for planning in many sectors. SPEAR is being tested for subseasonal prediction, which aims to fill the gap between short-term weather forecasts and long-term seasonal outlooks.

SPEAR is also used for making decadal and multidecadal climate change projections, with an emphasis on quantifying the changing risk of climate extremes, including extreme heat, floods, drought, and storms. The high spatial resolution of the model (50-km atmosphere/land grid) facilitates the simulation of regional climate and extremes. The output from a large suite of simulations with SPEAR, extending from 1921 to 2100, has been made publicly available. This data can be easily and freely downloaded, facilitating planning and assessment of changing climate risks on the regional scale over the 21^st century.