Australia’s Bureau of Meteorology has upgraded its assessment of the likelihood of an El Niño to 70% and warmer than normal temperatures are increasingly likely to make this current calendar year the warmest in recent history.
In its ENSO Wrap-Up of the Current state of the Pacific and Indian Oceans released on Wednesday the BOM said the Pacific Ocean has shown some renewed signs of El Niño development in recent weeks.
Above-average temperatures in the tropical Pacific Ocean have warmed further in the past fortnight, while the Southern Oscillation Index (SOI) has generally been in excess of El Niño thresholds for the past three months. Climate models suggest current conditions will either persist or strengthen. These factors mean the Bureau’s ENSO Tracker Status has been upgraded from WATCH to ALERT level, indicating at least a 70% chance of El Niño occurring.
Not all indicators have shifted towards El Niño. Tropical cloudiness near the Date Line and trade wind strength are close to average, suggesting the atmosphere is still not firmly linked with the warmer ocean below. However, trade winds have weakened several times over the past few months and SOI values have remained generally negative, suggesting at least some atmospheric response to the underlying ocean conditions.
International climate models expect the warm tropical Pacific Ocean temperatures to persist, with most models predicting values will remain near or beyond El Niño thresholds for the next two to three months. Regardless of whether or not El Niño fully develops, warmer-than-average tropical Pacific Ocean temperatures, combined with cooler waters currently to the north of Australia increase the chance of some El Niño-like impacts. For many parts of Australia, this suggests below average rainfall and above average temperatures in the months ahead (as shown by the November–January Climate Outlook).
That 2014 as a whole will be an extremely warm year is shown by the latest GLOBAL Land-Ocean Temperature figures from NASA. For the 10 months ended October the average temperature is only just behind that recorded in 2010.
Unless the forecasters are very wrong about the influence on world temperatures of a warm Pacific, then 2014 should surpass the record highs of 2005 and 2010.