Previous studies with single models have suggested that El Niño teleconnections over North America could be different in a
future warmer climate due to factors involving changes of El Niño event amplitude and/or changes in the midlatitude base state
circulation. Here we analyze a six-member multi-model ensemble, three models with increasing future El Niño amplitude, and
three models with decreasing future El Niño amplitude, to determine characteristics and possible changes to El Niño teleconnections
during northern winter over the North Pacific and North America in a future warmer climate. Compared to observed El Niño events,
all the models qualitatively produce general features of the observed teleconnection pattern over the North Pacific and North
America, with an anomalously deepened Aleutian Low, a ridge over western North America, and anomalous low pressure over the
southeastern United States. However, associated with systematic errors in the location of sea surface temperature and convective
heating anomalies in the central and western equatorial Pacific (the models’ anomaly patterns are shifted to the west), the
anomalous low pressure center in the North Pacific is weaker and shifted somewhat south compared to the observations. For
future El Niño events, two different stabilization experiments are analyzed, one with CO
2 held constant at year 2100 concentrations in the SRES A1B scenario (roughly doubled present-day CO
2), and another with CO
2 concentrations held constant at 4XCO
2. Consistent with the earlier single model results, the future El Niño teleconnections are changed in the models, with a weakened
as well as an eastward- and northward-shifted anomalous low in the North Pacific. This is associated with weakened anomalous
warming over northern North America, strengthened cooling over southern North America, and precipitation increases in the
Pacific Northwest in future events compared to present-day El Niño event teleconnections. These changes are consistent with
the altered base state upper tropospheric circulation with a wave-5 pattern noted in previous studies that is shown here to
be consistent across all the models whether there are projected future increases or decreases in El Niño amplitude. The future
teleconnection changes are most consistent with this anomalous wave-5 pattern in the models with future increases of El Niño
amplitude, but less so for the models with future decreases of El Niño amplitude.
The National Center for Atmospheric Research is sponsored by the National Science Foundation.