'The globally averaged temperature over land and ocean surfaces for May 2015 was the highest for the month of May since record keeping began in 1880. March–May and the year-to-date (January–May) globally averaged temperature were also record high.'
https://www.ncdc.noaa.gov/sotc/The new version is based on 'ocean (ERSST version 4.0.0) dataset'
'Q. What are the corrections to the ERSST dataset?
A. Version 4 of the ERSST dataset improves or corrects for several factors related to sea-surface temperature (SST) measurements. These include: updated and substantially more complete input data from ships and buoys, improved metadata associated with these observations, updated SST quality control procedures, revised SST anomaly evaluation methods, updated corrections to ship SSTs using nighttime marine air temperature, accounting for differences inherent in buoy (relative to ship-borne) observations, and improved methods of identifying and using persistent statistical relationships between neighboring regions to help validate observations and address missing data. Complete information on these changes is available in Huang et al. (2015).'
https://www.ncdc.noaa.gov/sotc/global/2015/5/supplemental/page-1/That is the Karl et al (2015) paper.
remember this?
' Re: 71 new papers 2013, Sun controls climate not CO2
Reply #43 - Jun 2nd, 2015 at 4:38pm Quote
I see NOAA, fresh from a "new version of the dataset" in 2014, which somehow, unrelated, gave us "the hottest year evah", is going to update the dataset again, next week. Any bets on a new "hottest year evah"? '