Rising ocean temperatures in the Pacific are at the core of the West Coast's precipitation patterns, driving winter storms, and could wind up causing the climate of the Pacific Northwest and Southwest to switch, a new study suggests.
Researchers from Cooperative Institute for Research in Environmental Sciences (CIRES), the National Oceanic and Atmospheric Administration and the University of Colorado have determined that ocean temperatures and not the planet's ice sheets, are 'directly responsible' for changing the North Pacific's atmosphere and the West Coast's precipitation patterns.
This happened during the Last Glacial Maximum, which occurred between 31,000 and 16,000 years ago and is currently happening now.
The changes are noteworthy given the fact it does not require an ice sheet to occur, the researchers said.
Scientists originally thought that during the Last Glacial Maximum, roughly 20,000 years ago, large ice sheets hovered over North America and these ice sheets caused the dramatic shift in the atmosphere's circulation.
Given that Pacific Ocean temperatures and West Coast precipitation patterns are linked, it could mean there could be a 'dramatic change' in the West Coast climate in a relatively short period of time.
'It is distinctly plausible that we could get an ocean temperature pattern in the North Pacific that looks very much like what we saw during the Last Glacial Maximum,' the study's lead author, Dillon Amaya, added.
'This could lead to dramatic changes in West Coast hydroclimate over a relatively short period of time, like decades.'
Amaya noted that although there is no change a nearly 2 mile tall (3 kilometers) ice sheet will appear 'suddenly' over North America, the modern climate 'can produce similar changes in North Pacific ocean temperatures that could temporarily swap the climates of the Southwest and the Pacific Northwest.'
Scientists originally thought that during the Last Glacial Maximum, roughly 20,000 years ago, large ice sheets hovered over North America and these ice sheets caused the dramatic shift in the atmosphere's circulation.
'This study highlights the need for a holistic view of the climate system, especially when modeling its past and future behavior,' said coauthor and CIRES Fellow Kris Karnauskas in a statement.
'Without accounting for the interaction between the atmosphere and ocean, you can end up with the right answer for the wrong reason, which is of course risky when you try to extrapolate that information to future concerns like freshwater availability.'
The study shows that the ocean temperatures of the Last Glacial Maximum were not unique to that time period.
The researchers note that during this period, the Southwestern U.S. was full of precipitation and the Pacific Northwest was dry, drastically different from how these regions are today.
It was believed the Northern Hemisphere ice sheets acted as a barrier and pushed the North Pacific jet stream and storms south, but after researching deeper, they found that was not the case.
'There's also the thermodynamic effect of having a really bright ice sheet that reflects a lot of sunlight,' Amaya explained. 'That creates cooling that also adjusts atmospheric circulation.'
The researchers used a climate model that also simulated the ocean's response to ice sheets and how it interacts with the atmosphere to come up with their findings.
'This study highlights the need for a holistic view of the climate system, especially when modeling its past and future behavior,' said coauthor and CIRES Fellow Kris Karnauskas explained.
'Without accounting for the interaction between the atmosphere and ocean, you can end up with the right answer for the wrong reason, which is of course risky when you try to extrapolate that information to future concerns like freshwater availability.'
'It is distinctly plausible that we could get an ocean temperature pattern in the North Pacific that looks very much like what we saw during the Last Glacial Maximum,' Amaya said.
'This could lead to dramatic changes in West Coast hydroclimate over a relatively short period of time, like decades.
Though the ice sheets do not play the preeminent role in pushing the storms south, they do play a role, albeit one that could be considered behind the scenes.
The study was recently published in the scientific journal Earth and Planetary Science Letters.