Understanding why the Antarctic Peninsula was warmed over the last half-century has been a complex study for scientists, as has been understanding the steady warming of the continental West Antarctica over the past 30.
But a new study out of the University of Washington finally provides a feasible answer for the warming, based on warming sea surface temperatures in the area of the Pacific Ocean along the equator and near the International Date Line.
According to the research shows that the warmer Pacific waters have driven atmospheric circulation that has caused some of the largest shifts in Antarctic climate in recent decades. The warmer water generates rising air that creates a large wave structure in the atmosphere that is known as a Rossby wave train, which brings warmer temperatures to West Antarctic during the winter and following spring.
A Rossby wave train is also the reason behind cooler temperatures in North East locales in the Northern Hemisphere, as seen in this recent study.
Though Antarctica is generally isolated by the Southern Ocean which surrounds the icy continent, the new results “show that it is still affected by climate changes elsewhere on the planet,” said Eric Steig, a UW professor of Earth and space sciences and director of the UW Quaternary Research Center.
The scientists behind the new research used surface and satellite temperature observations to show a strong statistical connection between warmer temperatures in Antarctica and sea surface temperatures in the central tropical Pacific Ocean. The warmer Antarctic temperatures are, on the, whole, brought by westerly winds associated with high pressure systems over the Amundsen Sea, which sits off the west coast of Antarctica. These warmer temperatures are theorized to originate from a series of high- and low-pressure cells that follow an arcing path from the tropical Pacific to West Antarctica, a textbook example of a Rossby wave train pattern.
The researchers found a strong relationship between central Pacific sea-surface readings and Antarctica temperatures during June through August, the Southern Hemisphere’s winter months. The spring months also showed the effect, though it was less pronounced, during September through November.