CMIP6 projections of Arctic indicators and midlatitude linkages

This proposal targets NOAA’s Modeling, Analysis, Predictions, and Projections (MAPP)
Program, Category (ii): 21st Century Integrated U.S. Climate Predictions and Projections. It
addresses Priority Areas A and C of this competition through a synthesis of CMIP6 (Coupled
Model Intercomparison Project, Phase 6) simulations and indicators relevant to Arctic-midlatitude
linkages, particularly linkages affecting the contiguous United States. By providinginformation on
the future trajectory of climate change indicators, the project will contribute to
the Climate Program Office goal of the prediction of climate and its impacts in support of
effective decision-making. The results will also inform future National Climate Assessments, by
which information on climate change will be conveyed to broader audiences in the U.S.

The upcoming availability of output from CMIP6 provides a timely opportunity for an
augmented assessment of the future trajectory of the Arctic climate system and its linkages with
climate variations in other regions, including the contiguous United States. With rapidly
warming temperatures, diminishing sea ice cover, and loss of glacial mass, the Arctic can be
viewed as a bellwether of global climate change. Existing indicators of Arctic change, developed
largely through NOAA support, document historical variations over recent periods ranging from
several years to more than a half century. Indicator variables are in hand for Arctic cold air mass,
sea ice, snow cover, wildfire activity, and summer thaw relevant to permafrost thermal state,
vegetative greenness, and glacier mass balance. There are also available indicators for
teleconnection patterns that capture the linkages between the Arctic and midlatitudes. However,
predictions for these Arctic and teleconnection indicators, accompanied by uncertainties, are
lacking. The proposed project will utilize CMIP6 model output to synthesize 21st-century
projections of key Arctic and U.S. mid-latitude indicators. The projections will be accompanied
by estimates of uncertainty arising from across-model differences, internal variability, and
alternative forcing scenarios. The synthesis of the CMIP6 projections will include the evaluation
of threshold exceedances in both the Arctic and the contiguous United States. The emergence of
Arctic-midlatitude linkages will be verified using atmospheric circulation metrics and
temperature and precipitation extremes in the U.S. We will also apply a recently developed
forecast method to obtain probabilistic predictions of key Arctic indicators over the next decade.