2014: A year of record-breaking temperatures?
December 2014 - Preliminary figures show that 2014 is on course to be the warmest year on record, both globally and for the UK. This report puts the climate of 2014 into context, drawing on observations and basic science to understand the drivers of the record setting year. It also examines the role of human influence, an analysis of the El Niño conditions and what this year means in the context of the 'pause' in global warming.
Preliminary figures show that 2014 is on course to be the warmest year, or one of the warmest years, on record, both globally and for the UK. The global mean temperature for January to October based on the HadCRUT4 dataset (compiled by the Met Office and the University of East Anglia's Climate Research Unit) is 0.57°C (+/- 0.1) above the long-term (1961-1990) average of 14.00°C. This is consistent with the statement from the World Meteorological Organization (WMO). With two months of data still to add, the full-year figure could change but presently 2014 is just ahead of the current record of 0.56°C set in 2010 in the global series which dates back to 1850. The final value will be very close to the central estimate of 0.57°C from the Met Office global temperature forecast for 2014, which was issued late last year.
For the UK, the mean temperature from 1 January to 25 November is 1.6°C above the long term (1961-1990) average, which means this year is currently the warmest in our UK series dating back to 1910. This would beat the record of 1.4°C set in 2006, but a cold December could change the final ranking for this year. This year is also set to be one of the warmest on record in the Central England Temperature (CET) series, which goes back to 1659.
Global average sea-surface temperatures in 2014 have been unusually warm, particularly in the latter half of the year. Record warm years in the global temperature record are frequently associated with the temporary warming influence of the El Niño/Southern Oscillation, but despite early signs of a developing El Niño this year, it has failed to grow beyond a weak signal. This was due to the persistence of above average temperatures in the tropical West Pacific Ocean, which stifled the atmospheric response that is necessary for an El Niño to mature. In 2014 the warmth of the northern mid-latitude and tropical western Pacific Ocean are likely to have made a substantial contribution to the global mean temperature and not El Niño.
The changes seen in the surface temperatures of the Pacific Ocean might suggest that the 'pause' in global mean surface warming is coming to an end. There is as yet no evidence to support this, but new research has continued to reinforce the role of decadal variations in ocean heat uptake as an important contributor to the 'pause'. Whilst the Pacific Ocean is still regarded as a major driver, the role of the Atlantic and Southern Oceans has also been highlighted.
Finally, the evidence for the influence of human emissions of greenhouse gases on this year's likely global mean surface temperature record is irrefutable. Even for the UK itself, the current record temperatures have been shown to be 10 times more likely because of human activities.