A new study released by the NOAA published Monday in the Proceedings of the National Academy of Science explains 113 years of temperature change in the Pacific West Coast is not due to human activities.
The cause for the change in warmer temperatures of about 1 degree Fahrenheit since 1990 was detailed in the study from from the National Oceanic Atmospheric and Administration, NOAA, in conjunction with the University of Washington. The computer models mapped the natural, wind-driven climate patterns in the Pacific Ocean, such as El Niño and the Pacific Decadal Oscillation. The acceptance of the two currents is known to exert influence on the sea and the land temperatures, which is now charted with the data collected over the 113 year period in the study.
“This does not call into question the concept of global warming,” cautions Kevin Trenberth, National Center for Atmospheric Research. Surface temperatures from the time period and the coastal wind speeds were studied and concluded that when the coastal winds lessen, the result is less evaporation from the sea surface. There exists a low pressure point that accounts for the lower temperatures of the ocean surface.
Study leader, James Johnstone and his colleague Nathan Mantua, who worked on the study at the University of Washington’s Institute for the Study of the Atmosphere and Ocean, determined that changing winds explain a large part of the warming from year after year. Weaker winds account for 80 percent of the Pacific Northwest coast between Washington and Northern California. Southern California displays that weaker winds account for 60 percent of the increased warming.
The study details that most of the warming temperatures on the Pacific Coast appeared before 1940 when winds were weaker. Greenhouse gases were low in that time period. When winds strengthened in the region since 1980, the coastal ocean cooled and greenhouse gases have accelerated in that time period. Johnstone noted in the study that, “West Coast sea surface and coastal air temperatures evolved in lockstep with changing patterns of atmospheric pressure and winds.”
Johnstone notes in the study that while greenhouse gases trap heat in the upper atmosphere, the surface winds dominate the heat transfers in the ocean temperature and dominate regionally. He states in the study that Pacific northeast coastal winds are counterclockwise. This guides the sea level temperatures.
Prior to greenhouse gases, tree-ring studies showed the link to temperature and century-long temperature trends. The Pacific Coastal winds have been a long-standing effect. “We’ve known that these fluctuations are in play over decadal scales and what we’re now seeing is that they can extend to century scales as well,” Johnstone said.
Trenberth, who was not involved in the study, cautions its conclusions. The long-term trends were probably overstated because the quality of data from the early 20th century was poor and unreliable. Computer data collection and models were not available for much of the data collection. The Pacific area may be low “noise” in relation to the “signal of climate change.”