The year 2015 is shaping up to be the hottest on record, the UN's weather agency said on 25 November, a week ahead of a crucial climate change summit in Paris.
"2015 is likely to be the hottest year on record, with ocean surface temperatures at the highest level since measurements began," said Michel Jarraud, head of the World Meteorological Organisation.
"This is all bad news for the planet," he added in a statement.
The WMO said data from the first 10 months of the year suggested temperatures over land and sea would tick in at their highest level ever measured this year, after already reaching record highs in 2014.
Rise in surface temperatures
The UN agency said the preliminary data showed the global average surface temperature has reached "the symbolic and significant milestone" of 1.0 degree Celsius above mid-19th century levels.
Global surface temperatures this year are also about 0.73 degrees Celsius above the 1961-1990 average of 14 degrees Celsius, WMO said.
The UN agency usually waits to have data stretching over a full year before drawing any conclusions, but said it wanted to release its preliminary findings "to inform negotiators at the UN Climate Change Conference in Paris."
More than 145 world leaders are set to gather in the French capital Monday to launch the 12-day conference aimed at securing a rescue pact for the global climate aimed at capping global warming at two degrees Celsius above the pre-industrial era.
"Greenhouse gas emissions, which are causing climate change, can be controlled," Jarraud said.
"We have the knowledge and the tools to act. We have a choice," he said. "Future generations will not."
Sea-surface temperatures hit new records last year, and WMO said today they were "likely to equal or surpass that record in 2015."
Since oceans have been absorbing more than 90 per cent of the energy accumulated in the climate system from human emissions of greenhouse gases, temperatures at greater depths are also rising, as are sea levels, the agency said
In the first nine months of 2015, global ocean heat content through both the upper 700 metres and 2,000 metres of the oceans hit record highs, it said.
Sea levels in the first half of the year meanwhile appeared to be "the highest since satellite observations became available in 1993."
China had its warmest January-to-October period on record, Africa is experiencing its second warmest year on record.
Severe heatwaves have hit India and Pakistan, as well as Europe, North Africa and the Middle East.