A new study suggests that the warming trend on the West Coast over the last century was not caused by human activity but more so by a change in the winds.
The research published in the journal Proceedings of the National Academy of Sciences acknowledged in the study significance that warming trends are “often ascribed to anthropogenic greenhouse forcing.” Using independent data from 1900 to 2012, researchers showed that the temperature change is “primarily attributed to changes in atmospheric circulation.”
This, they wrote, “presents a significant reinterpretation of the region’s recent climate change origins.”
“Surface winds and wind-driven ocean currents have large effects on temperatures in and around the northeast Pacific Ocean; they dominate the overall temperature variability and also account for a large fraction of the warming trend,” Jim Johnstone, lead author of the study, said in a statement. “West Coast sea surface and coastal air temperatures evolved in lockstep with changing patterns of atmospheric pressure and winds.”
To the Associated Press, Johnstone said that these findings show that “there are other factors stronger than the greenhouse forcing that is affecting those temperatures.”
According to the news release from the National and Atmospheric Administration’s Southwest Fisheries Science Center, the study, on a broader note, shows how regional climate could skew interpretations of what is going on with the climate on a global scale.
The study was met with skepticism by some climate experts.
“This may say more about the state of climate modeling than it says about causes of warming in the Pacific Northwest,” Ken Caldeira with the Carnegie Institution for Science’s Department of Global Ecology told the Associated Press in an email. “The authors … have not established the causes of these atmospheric pressure variations. Thus, claims that the observed temperature increases are due primarily to ‘natural’ processes are suspect and premature, at best.”
NOAA scientist Nathan Mantua, the study’s co-author, told the AP that they checked their data against other sources to reduce any inaccuracies. Mantua said that he expected the findings to “take people by surprise” because warming trends have long been linked to greenhouse gas concentrations and other anthropogenic activities.
NASA also released information about sea ice coverage in the Arctic, noting that it declined to a minimum that holds with the recent below-average trend. The minimum measured 1.94 million square miles, which NASA said is below the average of 2.40 million square miles recorded between 1981 to 2010.
“Arctic sea ice coverage in 2014 is the sixth lowest recorded since 1978. The summer started off relatively cool, and lacked the big storms or persistent winds that can break up ice and increase melting,” Walter Meier, a research scientist at NASA’s Goddard Space Flight Center, said in a statement.
“Even with a relatively cool year, the ice is so much thinner than it used to be,” Meier added. “It’s more susceptible to melting.”
World leaders met Tuesday in New York City for the one-day U.N. Climate Summit to discuss the state of the climate and what to do about it. United Nations Secretary-General Ban Ki-Moon challenged the more than 100 leaders in attendance to set a new course for a warming world and reverse the rise of heat-trapping gases.
Ban said the world is facing an unprecedented challenge. He said Earth needs all hands on deck to weather the storm of climate change.
President Barack Obama pledged to sign an executive order requiring the U.S. government to take climate change into account when it spends money overseas to help poorer countries.
Obama is also announcing new tools the U.S. will offer vulnerable populations abroad to help them address the effects of climate change through science and technology. The White House said the U.S. will take part in more than a dozen new partnerships aimed at fighting global warming.
The measures are among a host of commitments Obama is announcing Tuesday at a climate summit during the United Nations General Assembly.
The Associated Press contributed to this report.
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