London (AFP) - Global mean surface temperatures this year are set to reach one degree Celsius above pre-industrial levels for the first time, Britain's Met Office said Monday.
Data from January to September showed global mean temperature at 1.02 C above 1850-1900 levels," the national weather service said.
The data has a 0.11 C margin of error.
"This represents an important marker as the world continues to warm due to human influence," the Met Office said.
Stephen Belcher, director of the Met Office Hadley Centre, said: "We have seen a strong El Nino develop in the tropical Pacific this year and that will have had some impact on this year's global temperature.
"We've had similar natural events in the past, yet this is the first time we're set to reach the 1C marker and it's clear that it is human influence driving our modern climate into uncharted territory."
The Met Office said early indications suggested 2016 would be similarly warm.
"While it's more difficult to say exactly what will happen in the years immediately after that, we expect warming to continue in the longer term," it said.
Peter Stott, head of climate monitoring and attribution, explained: "This year marks an important first but that doesn't necessarily mean every year from now on will be a degree or more above pre-industrial levels, as natural variability will still play a role in determining the temperature in any given year.
"As the world continues to warm in the coming decades, however, we will see more and more years passing the one degree marker -- eventually it will become the norm."
The Met Office study came as ministers met in Paris searching common ground ahead of a crunch climate summit.
Environment and energy ministers are seeking convergence on issues still dividing nations negotiating for a climate rescue pact to be inked at a November 30-December 11 United Nations summit in the French capital.
Last month, scientists said the first nine months of 2015 had been the hottest on record worldwide.