Can Large Scale Sea Ice Cover Changes Affect Precipitation Patterns over California?

Thursday, December 17, 2015 - 08:30
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Pronounced Arctic sea ice loss since the beginning of the satellite era has intensified the interest into whether these high latitude changes can significantly influence the weather and climate far from the Arctic. Current attempts to demonstrate statistically significant remote responses to sea ice changes have been hindered by factors such as large high latitude variability, relatively short observational datasets, and model limitations in adequately representing current sea ice changes.

In this study, we sample uncertainty in sea ice physics parameters and variability in atmospheric initial conditions to obtain an ensemble of simulations with substantially different states of Arctic and Antarctic sea ice cover. This large ensemble isolates a robust, statistically significant climate change response arising from changes in sea ice cover only.

Our results show a significant link between Arctic and Antarctic sea ice cover changes and precipitation across the tropical Atlantic and Pacific basins, the Sahel, and the west coast of the United States. For example, large Arctic sea ice decline leads to a northward shift of the tropical convergence zone, increased subsidence over the southwest United States and a geopotential anomaly over the North Pacific; with all of these factors resulting in significant drying over California.

We conclude that high-latitude sea ice cover changes are an important driver of low-latitude precipitation. Consequently, reliable predictions of future precipitation changes over areas such as California (and the Sahel) will strongly depend on our ability to adequately simulate both Arctic and Antarctic sea ice changes.