Humans -- and the greenhouse gas emissions they bring about -- are not responsible for the temperature increases in the waters of the Pacific Ocean off the North American coast for the past century, says a new study in the Proceedings of the National Academy of Sciences journal.
The two researchers, formerly scientists at the University of Washington, say they found no evidence that human-caused greenhouse gas emissions influenced the changes in weather patterns.
The study points to the natural, changing course of the wind and circulation of air instead.
"These results suggest that natural internally generated changes in atmospheric circulation were the primary cause of coastal NE Pacific warming from 1900 to 2012 and demonstrate more generally that regional mechanisms of interannual and multidecadal temperature variability can also extend to century time scales," says the study titled "Atmospheric controls on northeast Pacific temperature variability and change, 1900–2012."
Jim Johnstone, the study's lead author who was still climatologist at the Joint Institute for the Study of the Atmosphere and Ocean at the University of Washington when he worked on the project, says in various reports that it is clear that other factors, which are stronger than gas emissions, affect warming temperatures.
The researchers discovered that the wind was responsible for over 80 percent of the warming temperatures from Northern to Northwest California, and around 60 percent in Southern California.
It has been debated for years that the burning of fossil fuels by man is a big factor in rising regional temperatures. While the researchers blamed the natural course of the wind for that, they likewise clarify they do not disprove the idea that global temperatures are rising or that human beings have a hand in it.
"This doesn’t say that global warming is not happening," says co-author of the study Nate Mantua, who works with NOAA Fisheries' Southwest Fisheries Science Center, in a report by The Seattle Times. "It doesn’t say human-caused climate change isn't happening globally. It's a regional story."
They say it just so happened that the Northwest is a region where weather and wind sway more wildly than do those in the tropics, for instance, thereby hiding any climate signals.
The scientists also don't claim that greenhouse gases won't be an important factor soon.
The two scientists of the study considered the possible data inaccuracy into account and compared these to many other sources.
Other climate scientists, however, faced this new study with much skepticism. In a Washington Post report, the climate scientists argued that though the study found a correlation, there was no rigorous computer and statistical analysis showing the reason behind changes in the wind was natural.
