The El Nino phenomena is among the most fascinating yet least
understood topics of climate science. Every few years a wave of heat and
surface pressure changes sweeps across regions of the Pacific. It lasts
nine months to two years and has a worldwide effect.
Some believe that the frequency of El Ninos is changing as a result of climate change. I have recently heard it said many times that it is the increased frequency of El Nino and the associated La Nina that has resulted in the flatness of the global annual average temperature in the past decade or so. If true it’s an important observation.
Trenberth and Hoar in 1996 said there is a tendency for more frequent El Nino and fewer La Nina since the late 1970’s which they think is linked to decadal changes throughout the Pacific basin due to global warming. They note a non-El Nino warming between 1990-95 “connected to” the El Nino, which they say is unprecedented in the previous 113 years, and suggest it is linked to increases in greenhouse gasses.
Following criticism of their paper Trenberth and Hoar 1997 restated their assertions saying the El Nino from 1990-95 was unusual and that the pattern seen since late 1970s was unlikely to be due to natural variability. However, Solow 2006 pointed out statistical shortcomings in Trenberth and Hoar and questioned their conclusions. Rajagopalan et al also disputed Trenberth and Hoar and using a more sophisticated statistical analysis said that any changes seen in El Nino is due to natural variability. Subsequently, Solow and Huppert 2003 did not consider the 1990-95 ‘event’ significant. They also don’t see a change in ENSO frequencies. Indeed, reversing the philosophy of Trenberth and Hoar, Soon-Il An et al 2003 say that it is not background global warming that is driving changes in El Nino but the other way around; the strong El Nino of 1998 had a strong influence on the Earth’s climate.
Read more: http://thegwpf.org/the-observatory/6136-el-nino-and-global-warming.html
Some believe that the frequency of El Ninos is changing as a result of climate change. I have recently heard it said many times that it is the increased frequency of El Nino and the associated La Nina that has resulted in the flatness of the global annual average temperature in the past decade or so. If true it’s an important observation.
Trenberth and Hoar in 1996 said there is a tendency for more frequent El Nino and fewer La Nina since the late 1970’s which they think is linked to decadal changes throughout the Pacific basin due to global warming. They note a non-El Nino warming between 1990-95 “connected to” the El Nino, which they say is unprecedented in the previous 113 years, and suggest it is linked to increases in greenhouse gasses.
Following criticism of their paper Trenberth and Hoar 1997 restated their assertions saying the El Nino from 1990-95 was unusual and that the pattern seen since late 1970s was unlikely to be due to natural variability. However, Solow 2006 pointed out statistical shortcomings in Trenberth and Hoar and questioned their conclusions. Rajagopalan et al also disputed Trenberth and Hoar and using a more sophisticated statistical analysis said that any changes seen in El Nino is due to natural variability. Subsequently, Solow and Huppert 2003 did not consider the 1990-95 ‘event’ significant. They also don’t see a change in ENSO frequencies. Indeed, reversing the philosophy of Trenberth and Hoar, Soon-Il An et al 2003 say that it is not background global warming that is driving changes in El Nino but the other way around; the strong El Nino of 1998 had a strong influence on the Earth’s climate.
Read more: http://thegwpf.org/the-observatory/6136-el-nino-and-global-warming.html
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