Nation/World

2016 'very likely' to be the hottest year on record, U.N. agency declares

Timed for the ongoing international climate meetings in Marrakech, Morocco, the United Nations' World Meteorological Organization has affirmed what many scientists had already considered inevitable – 2016, the agency said, will "very likely" be the hottest year on record. That would mean that the last three years – 2014, 2015 and 2016 – have set ever more impressive temperature records in quick succession.

The agency was able to say as much, despite the year not even being over yet, due to the jaw-dropping heat seen throughout much of the year. Multiple months in 2016 set new monthly temperature records, buoyed by a very strong El Niño event.

Sixteen "of the 17 hottest years on record have been this century," noted the agency.

Overall, the WMO said, 2016 was 1.2 degrees Celsius warmer on average than temperatures for the pre-industrial Earth. That's a highly significant number, in that it puts the planet quite close to the 1.5 degree Celsius temperature threshold enshrined as an aspirational goal in the Paris climate agreement. Some scientists have said we could cross 1.5 degrees for good by 2030.

The agency noted that warmth in the Arctic was particularly extreme in 2016. "In parts of Arctic Russia, temperatures were 6°C to 7°C above the long-term average. Many other Arctic and sub-Arctic regions in Russia, Alaska and northwest Canada were at least 3°C above average. We are used to measuring temperature records in fractions of a degree, and so this is different," said Petteri Taalas, the Secretary-General of the WMO, in a statement.

The warmth accompanied a host of new records, including a peaking of atmospheric carbon dioxide concentrations at 407.7 parts per million in May at the Mauna Loa Observatory in Hawaii, and astounding winter warmth, with February and March in particular blowing out past global temperature records by considerable margins.

This early move to crown 2016 – albeit only in a preliminary way — does not come as much of a surprise. The warmth was so off the charts in early 2016 that as early as May, Gavin Schmidt, who directs the NASA-Goddard Institute for Space Studies (which manages one highly influential temperature dataset), tweeted that 2016 was more than 99% likely to be a new record.

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There were also some oddities in 2016 – one patch of ocean near the Antarctic Peninsula remained surprisingly cool all year. "The most prominent area of below-normal sea surface temperatures was the Southern Ocean south of 45° South (especially around the Drake Passage between South America and Antarctica, where temperatures were more than 1°C below normal in places)," wrote the WMO.

The El Niño event also brought on a surprising surge in global sea levels, which rose 15 millimeters between late 2014 and early 2016, far outstripping the usual pace of around 3 millimeters per year, the WMO reports.

While the WMO relied on data from NASA and the National Oceanic and Atmospheric Administration in proclaiming the 2016 record, these agencies have not themselves announced a formal record yet. They will presumably do so early next year once all the data are in. The WMO itself said its statement is "provisional" and will be updated in early 2017.

At this point in time, it seems unlikely that 2017 will set yet another temperature record and exceed that of 2016, especially since the El Niño event has concluded and the world has swung back to La Niña conditions. But that hardly detracts from a record run of temperatures that have coincided with an unprecedented global policy push towards climate action.

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