Climate: Parts of the tropical Pacific Ocean are shifting toward a permanent El Niño-like pattern

Archived ocean observations help create new data set for climate models

Atmospheric circulation patterns drive convection in the tropics and can have a far-reaching effect on global climate. Bob Berwyn photo.

By Summit Voice

SUMMIT COUNTY — A new set of more complete sea surface temperature data has helped scientists explain a gradual, decades-long slowdown of a key tropical atmospheric circulation, linking it with the steady increase in global temperatures during the past few decades.

“Our experiments show that the main driver of the change in the Walker circulation is the gradual change that has taken place in the surface temperature pattern toward a more El Niño-like state,” said Hiroki Tokinaga, associate researcher at the International Pacific Research Center, University of Hawaii at Manoa. “We don’t have enough data yet to say to what degree the slowdown over the last 60 years is due to a rise in man-made greenhouse gases or to natural cycles in the climate,” Tokinaga said.

The Walker circulation determines much of the tropical Indo-Pacific climate and has a global impact as seen in the floods and droughts spawned by the El Niño-Southern Oscillation. Meteorological observations over the last 60 years show this atmospheric circulation has slowed: the trade winds have weakened and rainfall has shifted eastward toward the central Pacific. Continue reading

Melting ice only one factor in rising sea levels

Melting ice caps are not the only thing driving rising sea levels, according researchers from the University of Colorado and the National Center for Atmospheric Research.

Shifts in currents and winds also affecting sea level, with potential impacts in low-lying coastal zones

By Summit Voice

SUMMIT COUNTY — Colorado scientists who teamed up to study rising sea levels say some low-lying areas in the Pacific could be hit especially hard as global temperatures continue to climb. Because of complex patterns of ocean currents and winds, sea level is actually falling slightly in other areas, the researchers concluded.

The study, led by scientists at the University of Colorado at Boulder and the National Center for Atmospheric Research, also in Boulder, finds that the sea-level rise is at least partly a result of climate change. The changes are especially intense along the coastlines of the Bay of Bengal and the Arabian Sea, as well as the islands of Sri Lanka, Sumatra and Java, the research found.

The key player in the process is the Indo-Pacific warm pool, an enormous, bathtub-shaped area spanning a huge area of the tropical oceans stretching from the east coast of Africa west to the International Date Line in the Pacific. Continue reading

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