This is the first time for 3 - 5 million years and way above the average level of 280ppm prior to 1800. Interestingly the WMO is not, by and large, a climate change champion nor a denier, it mostly puts out the numbers with possible explanations for them.
This time, however, it has gone a bit further. It explains that the El Niño factor was partly in play, probably to stall some deniers, but it also goes on to say that despite recent measures to cut HCFCs (they did not exist in 1800) the levels of methane and and nitrous oxide are both above pre-industrial levels - 2.5 and 1.5 respectively.
The study also points to the impact of these increased concentrations of warming gases on the world's climate.
Between 1990 and 2015 there was a 37% increase in radiative forcing or warming effect, caused by a build up of these substances, from industrial, agricultural and domestic activities.
and,
"It is therefore of the utmost importance that the Paris Agreement does indeed enter into force well ahead of schedule on 4 November and that we fast-track its implementation."
Fast-track, by two weeks! That will work.
It is us. Bugs and animals do not do industry and agriculture. We are the ones needing fixing. Got it?