NEW YORK • This year is off to a record-breaking start for global temperatures.
It has been the hottest year to date, with January, February and March each passing marks set last year, according to new data from the US National Oceanic and Atmospheric Administration (NOAA).
March was also the 11th consecutive month to set a record high for temperatures, which agencies started tracking in the 1800s.
With the release on Tuesday of its global climate report, the NOAA is the third independent agency - along with Nasa and the Japan Meteorological Association - to reach similar findings, each using slightly different methods.
The reports add a sense of urgency at the United Nations, where world diplomats are gathered this week to sign the climate accord reached late last year in Paris. Since the initial agreement was reached, other global anomalies have been reported that punctuate the threat of climate change, including troubling trends on Arctic sea ice, floods, drought and carbon dioxide levels in the atmosphere.
Some of these can be explained in part by this year's El Nino phenomenon, which scientists predicted would release large amounts of heat from the Pacific Ocean into the atmosphere, causing irregular weather patterns across the globe.
But the effects of the current El Nino have been exacerbated by global warming, a result of emissions of greenhouse gases by humans, said Dr Jessica Blunden, a climate scientist with the NOAA and lead author of the report.
El Nino is on its way out, and ocean temperatures in the tropical Pacific peaked in November, said Dr Kevin Trenberth, a senior scientist at the National Centre for Atmospheric Research.
But the heat the ocean had stored had to go somewhere: "It's come out and been distributed around the world", which helps explain record warm temperatures and wildfires in the southern hemisphere, Dr Trenberth said.
To get an idea of how much of the record heat is caused by this El Nino and how much by global warming, Dr Blunden said that scientists at the NOAA compared this El Nino to the last strong one in 1997-98, which was also record-setting for its warmth.
The current one has pushed past those records by raising global temperatures an additional 0.8 deg C or so, Dr Blunden said. The high temperatures last month probably signalled the last gasp of El Nino, and surface temperatures across the globe are likely to begin to fall soon.
Often, El Ninos are followed by La Nina storm systems, which can usher in cooler periods, Dr Blunden said.
But after more than two record-setting hot years - 2014 and last year and an extremely warm few months of this year - many of the devastating effects of the one-two punch of global warming and El Nino may be inescapable.
Dr Trenberth said that these conditions did not represent "a new normal" and that it was difficult to determine the long-term consequences of this El Nino on both global temperatures and Arctic sea ice cover.
He is not sure if 2016 will prove to be as warm as last year - "I'm betting it's a toss up," he said - but added that it's not just the record heat that comes as a shock.
The magnitude of the jump "is indeed surprising", Dr Trenberth said.
A central feature of the Paris climate agreement was to hold the increase in the global average temperature to less than 2 deg C warmer than pre-industrial levels, and to try to limit the increase to about 1.5 deg C. As global temperatures are already nearing the 1.5-deg C threshold, and some months have been about 1 deg C or more above average, this goal might be difficult to achieve, Dr Trenberth said."I don't see at all how we're going to not go through the 1.5 deg C number in the next decade or so," he said.