Last week, in an announcement that not only drew massive media attention but was seized upon by President Obama in his State of the Union address, NASA and NOAA jointly declared that 2014 was the hottest year ever recorded, based on temperature records that go back to the year 1880.

The news came out on Fridaymorning. It was announced through press releases by the agencies, but also through more thorough discussions for the public and media, including this PowerPoint presentationand a media briefingdiscussing it.

Why revisit all of this? Because since the announcement there has been a strong reaction, and a lot of climate skeptics have suggested that really, 2014 might not have been the hottest year after all. Consider, for instance,this articlein the UKsDaily Mail,whosefirst sentence reads, The Nasa climate scientists who claimed 2014 set a new record for global warmth last night admitted they were only 38 per cent sure this was true.

Given the stakes here this is the biggest news story about climate change in quite some time I think it is important to examine this charge. For further discussion of the matter, by the way, you should also seethis postby Andrew Revkin at theNew York Timesandthis oneby Andrew Freedman at Mashable.

So whats up with this 38 percent figure, and does it really undermine the idea that 2014 was the hottest year on record?

The figure comes from slide 5 of the PowerPoint presentationmentioned above, where NASA scientists noted that there was a 38 percent chance that 2014 was the hottest year, but only a 23 percent chance that the honor goes to the next contender, 2010, and a 17 percent chance that it goes to 2005.

The same slide shows that NOAAs scientists were even more confident in the 2014 record, ranking it as having a 48 percent probability, compared with only an 18 percent chance for 2010 and a 13 percent chance for 2005. Here is the slide:

According to a NASA spokesman, the PowerPoint containing this slide went online at the same time that the 2014 temperature record itself was announced. So it may not have been as prominent as the press releases from the agencies, but it was available.

The slide was also discussed in the press briefingwhen the news of the new record was released. In the briefing,NOAAs Thomas Karl, director of the National Climatic Data Center, noted:

Certainly there are uncertainties in putting all this together, all these datasets. But after considering the uncertainties, we have calculated the probability that 2014, versus other years that were relatively warm, were actually the warmest year on record. And the way you can interpret these data tables is, for the NOAA data, 2014 is two and a half times more likely than the second warmest year on record, 2010, to actually be the warmest on record, after consideration of all the data uncertainties that we take into account. And for the NASA data, that number is on the order of about one and a half times more likely than the second warmest year on their records, which again, is 2010. So clearly, 2014 in both our records were the warmest, and theres a fair bit of confidence that that is indeed the case, even considering data uncertainties.

See more here:

Sorry, skeptics: NASA and NOAA were right about the 2014 temperature record