"The provisional information for 2014 means that 14 out of the 15 warmest years on record have all occurred in the 21st century. There is no standstill in global warming," said Michel Jarraud, the secretary general of the WMO.
"What we saw in 2014 is consistent with what we expect from a changing climate. Record-breaking heat combined with torrential rainfall and floods destroyed livelihoods and ruined lives," he added.
"What is particularly unusual and alarming this year are the high temperatures of vast areas of the ocean surface, including the northern hemisphere. Record-high greenhouse gas emissions and associated atmospheric concentrations are committing the planet to a much more uncertain and inhospitable future."
Christiana Figueres, executive secretary of the United Nations convention on climate change, said: "Our climate is changing and every year the risks of extreme weather events and impacts on humanity rise."
The global mean temperatures for January to October are based on worldwide instrument readings compiled by the Met Office and the University of East Anglia (UEA), known as the HadCRUT4 dataset. The Met Office said that the final value for the year will be very close to its central estimate of 0.57C for 2014, a forecast it made at the end of last year.
"Spatially, 2014 has so far been warmer than the 1961-1990 average almost everywhere, the main exception being central and eastern parts of North America. For Europe, many countries in northern and eastern parts will likely have had near-record warm years," said Phil Jones, director of UEA's climatic research unit.
Average air temperatures taken over land for January to October were about 0.86C above the long-term average between 1961 and 1990, which is so far about fourth or fifth warmest on record.
However, the global sea-surface temperatures were the highest on record, at about 0.45C above the average. Also, the ocean heat estimates at depths of 700m and 2000m for January to June were also the highest recorded, according to the WMO.
"Around 93 per cent of the excess energy trapped in the atmosphere by greenhouse gases from fossil fuels and the other human activities ends up in the oceans. Therefore, the heat content of the oceans is key to understanding the climate system," the WMO said.
The Met Office emphasised that one warm year has to be looked at in the context of longer-term trends of several decades. However, new techniques allow scientists to gauge the role of human activity in the changes of breaking temperature records, according to Peter Stott, head of climate attribution at the Met Office.
"Our research shows current global average temperatures are highly unlikely in a world without human influence on the climate," Dr Stott said.
A year of extremes
• Surface temperatures over land in 2014 are currently running at 0.86C above the long-term 1961-1990 average
• Heatwaves occurred in South Africa, Australia and Argentina in January, and Australia experienced another prolonged warm spell in May. Several South American countries reported record heat in October, although there were notable cold spells affecting the US during the winter, Australia in August and Russia in October.
•More significant, perhaps, was the record sea-surface temperatures, about 0.45C above the long-term global average. An El Nino-Southern Oscillation in the South Pacific - a reversal in ocean currents with warmer-than-average sea-surface temperatures - did not develop. However, many weather patterns associated with it did occur.
- Independent.
