If 2016 justifies its reputation in the next two months, which is "very likely" to happen, it will mean that the 21st century will see 16 of the 17 hottest years recorded.
"Another year. Another record. The high temperatures we saw in 2015 are set to be beaten in 2016," WMO secretary general Petteri Taalas said in a statement, adding that although the powerful El Nino phenomenon of 2015-16 has dispersed, the heating is not going to stop.
Arctic sea ice levels were "well below normal" throughout the year, according to the report, while ocean temperatures spiked, contributing to devastating coral bleaching and damaging marine ecosystems in tropical waters.
Concentrations of planet-warming greenhouse gases in the atmosphere increased to 400 parts per million last year and are expected to surpass that record in 2016.
The WMO also stressed that the effects of global warming are resulting in disastrous consequences, including heatwaves, flooding and storms, events that have become much more frequent, no longer ‘once in a generation' occurrences.
The WMO report was published as UN climate talks in Marrakesh entered their second week. The meeting is the first first since last year's huddle in France which resulted in the unprecedented climate-rescue Paris Agreement.
