All their slides and graphs can be found here.
It's only the warmest year in the Hadley Centre's records, which go back further. Warmest than 2015 by 0.01°C. Their error bars are ± 0.1°C, so they say 2016 was "nominally" the warmest, though the difference wasn't statistically significant.
The difference between the three datasets is mostly in how they treat the Arctic, where there are few temperature stations but which is now warming very fast. The Met Office explains here.
A few notes I took while listening:
- NOAA estimated the El Nino contributed about 1/4th to 1/3rd of their 2016-2015 difference. I didn't understand what GISS said about this, and will try to follow up.
- Journalists asked more than once what message they would send to the Trump administration, and both times Deke Arndt of NOAA cautiously said (paraphrasing), we produce our results for the American people to use as they see fit.
- Gavin Schmidt, Director of GISS, said a few interesting things in response to questions.
- 2016 is likely the warmest year for "many hundreds of years."
- However, we're still not as warm as the Eemian, the last interglacial 125,000 yrs ago.
- We've "clearly passed 1°C warming, and unlikely we'll go below that."
- His personal prediction is that 2017 will be "still a top five year, I'm pretty confident, but unlikely to be a record year." And, "possibly the second warmest."
- The Arctic is warming at 2-3 times the rate of the global mean.
- Deke Arndt of NOAA gave a graph of their data with and without corrections ("adjustments," a word he didn't use). He stressed that the biggest difference between raw and corrected data is in sea surface temperatures, with a change in ship data collection from buckets thrown overboard to the engine intake method. And he and again reiterated that corrections reduce the long-term warming trend: