I watch with great interest the twice a month reports from the Australian Bureau of Meteorology (BOM) on the the El Niño–Southern Oscillation (ENSO) because what happens to world temperatures the next time an El Niño occurs will have a major influence on the global warming debate. The evidence seems to suggest that under the influence of El Niño temperatures rise and a new high temperature reading for the world would be a blow to those who argue that global warming has plateaued over the last 15 years or so. Conversely, an El Niño that does not break the plateauing trend line would be manna from heaven for the climate sceptics.
Today’s report from the BOM continues to point to an El Niño being likely.
Based on the assessment on 1 July 2014, the El Niño–Southern Oscillation (ENSO) Tracker status remains at El Niño ALERT level, meaning that there is at least a 70% chance of an El Niño occurring in 2014. Current observations and model guidance indicate an El Niño is likely to develop by spring.
El Niño conditions generally result in below average winter/spring rainfall over southern and inland eastern Australia, while southern Australia typically experiences warmer days.
While the tropical Pacific Ocean surface temperature is currently at levels typically associated with a weak El Niño, waters below the surface have cooled and atmospheric patterns continue to remain neutral. However, over the past fortnight changes have occurred in the atmosphere that may be a response to the warm surface waters–the Southern Oscillation Index has dropped by over 10 points, and weakened trade winds have re-appeared. These changes would need to persist for several weeks in order for an El Niño to be considered established, and it remains possible they are simply related to shorter term weather variability.
Climate models surveyed by the Bureau continue to indicate that El Niño is likely to develop by spring 2014. The Bureau’s ENSO Tracker remains at El Niño ALERT, indicating at least a 70% chance of El Niño developing in 2014. For Australia, El Niño is often associated with below-average rainfall over southern and eastern inland areas and above-average daytime temperatures over southern parts of the continent. The Indian Ocean Dipole (IOD) is currently neutral. Model outlooks suggest the IOD is most likely to remain neutral through winter and spring. The likelihood of a positive IOD event increases with El Niño. Positive IOD events are typically associated with large parts of southern and central Australia experiencing lower rainfall than usual.