El Niño keeps New Zealand cooler in 2015
The effects of El Niño will prevent New Zealand from recording a record temperature for the year, say NIWA climate scientists.
Their analysis follows a statement from the World Meteorological Organisation (WMO) that the global average surface temperature in 2015 is likely to be the warmest on record, due to a combination of a strong El Niño and global warming.
However, NIWA principal climate scientist Dr Brett Mullan says New Zealand is “nowhere near its warmest on record”.
“New Zealand, in particular, often behaves differently to the global average because of El Niño.
“The characteristic of El Niño is a very large area of warmer water along the tropical Pacific that pumps heat into the global atmosphere and makes the globe warmer. But for New Zealand, El Niño produces more southerlies and south westerlies a lot of the year so we often average out to be below normal.”
So far this year New Zealand was more half a degree colder than 1998 which holds the record as the country’s warmest year on record, according to NIWA’s Seven Station Series. The seven station series is an analysis of temperature trends from climate station data at seven geographically representative locations for which there is more than 100 years of climate records.
In 1998, New Zealand was about 0.9°C above the 1981 to 2010 climatological average, followed by 1999, 2013 and 2005 and 1971 on fourth equal.
Dr Mullan says while New Zealand is experiencing significant long term warming, the year by year variability can be quite different to the global pattern.
“At the moment we’re running about 0.3°C above normal for 2015. We’re certainly warmer than the average but there’s no way we’re going to get up to the 0.9°C of 1998.”
The Intergovernmental Panel on Climate Change (IPCC) estimates the 100-year global combined land and ocean temperature trend from 1901 to 2012 is 0.89°C. For New Zealand, the seven station trend over 1909 to 2014 is 0.97°C, which is slightly smaller than the global land-only trend over the same period.
New Zealand’s warmest years since 1909, relative to 1981-2010 average
1st: 1998, +0.88°C above average
2nd: 1999, +0.81°C above average
3rd: 2013, +0.77°C above average
4th equal: 2005 and 1971, +0.57°C above average
For comparison, 2015 (January to October) is +0.27C above average.
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