Isn't the natural El Niño cycle to blame for atmospheric global warming?

El Niño events can raise the average global temperature by a few tenths of a degree Fahrenheit for a year or two. Likewise, La Niña events can produce a comparable cooling effect. Neither of these short-lived cyclic phenomena explain the longer-term warming observed in the last century and especially in the last 30 to 40 years. (These effects have been investigated for some time. For an in-depth report updated in 2001, see Children of the Tropics: El Niño and La Niña.)