Read here. In an attempt to hype global warming fears, the IPCC Climategate AGW-scientists have speculated that human CO2 emissions would massively influence ocean climate modes such as ENSO and the North Atlantic Oscillation. This speculation led to the hysterical hypothesis that increased CO2 emissions would cause a permanent El Niño condition. Like most IPCC claims designed to pressure policymakers, this one was also pure science fiction.
A study by Kemp et al. determined that the wide variability of modern ocean climate patterns is very similar to the natural variations found some 75 million years ago during the Late Cretaceous period. That period also had extremely high levels of atmospheric CO2 but no El Niño "tipping point" ever resulted - the natural ocean modes just kept on being variable.
"Based on reconstructions of Arctic climate variability in the greenhouse world of the Late Cretaceous, scientists have concluded that man-made global warming probably would not greatly change the climatic influence associated with natural modes of inter-annual climate variability such as the El Niño – Southern Oscillation (ENSO) or the Arctic Oscillation/ North Atlantic Oscillation (AO/ NAO).....“A key question is how an Arctic without permanent ice cover will affect atmospheric circulation and climate variability, particularly over high and mid latitudes,”.....“Understanding Late Cretaceous climate should inform debate about future climate trends and variability under greenhouse conditions,”.....“Based on our findings, it seems unlikely that man-made global warming would cause a permanent El Niño state." [Alan Kemp, Andrew Davies, and Heiko Pälike 2010: Geophysical Research Letters]
Additional peer-reviewed and ocean-pattern postings.