JMA is only the first in line to make their announcement. NASA, NOAA, and the Climatic Research Center in the UK are expected to confirm that 2014 was the hottest year on record. Each of these scientific research organizations tasked with studying climate uses a slightly different data set, so if all four reach the same conclusion it is safe to say the conclusion is definitive. The World Meteorological Organization (WMO), the United Nations complement to the national agencies, had already announced in December that it expected 2014 to be the hottest year ever.
According to the JMA, 2014 "was +0.27°C above the 1981-2010 average (+0.63°C above the 20th century average), and was the warmest since 1891. On a longer time scale, global average surface temperatures have risen at a rate of about 0.70°C per century."
While temperatures can vary regionally and the global values are the metric used, the UK Met Office also noted that 2014 was the hottest year ever in the UK. Here the increase was even more pronounced, with the average temperature in their data set at "9.9C, some 1.1C above the long term average, and making it warmer than the previous record year of 2006." Similar heat records were seen in Europe, Siberia, Australia, and California.
With 2014 setting a new record, it joins joins the previous 10 hottest years, all of which have occurred since climate deniers claimed "the planet stopped warming." Needless to say, that falsehood is shown to be even more ridiculous, and as noted by the IPCC, "warming of the climate system is unequivocal."
At this point it's important to put 2014 in context. Global average temperatures do fluctuate from year to year because of short-term phenomena like El Nino, La Nina, and various "oscillations" (circulatory systems that impact weather and short-term climatic conditions). What is more critical than 2014 setting a new heat record is that it continues a trend we've been experiencing for the last few decades. Each of the last three decades has been warmer than the decade before. It's undeniable - the climate is warming.
And it's warming despite the fact that short-term phenomena should be slowing the warming. The last really big El Nino year, which tends to help warming, was 1998. Since then we've had fewer El Nino's and more La Nina's. La Nina's tend to temporarily depress the warming caused by CO2. We've also seen an increase in aerosol emissions from the growing middle class populations in China and India. On top of that has been a rather tepid solar activity. All of these would be expected to tamp down warming.
And still is warms.
Unlike 1998, which was fed by the strongest El Nino on record, 2014 had almost no El Nino at all. But that seems to be changing - the long-awaited El Nino finally seems to be starting, which the record set in 2014 may fall in 2015.
And that may just be the beginning.
