The NOAA reports:
The globally averaged temperature over land and ocean surfaces for 2015 was the highest among all years since record keeping began in 1880. During the final month, the December combined global land and ocean average surface temperature was the highest on record for any month in the 136-year record.
- During 2015, the average temperature across global land and ocean surfaces was 1.62°F (0.90°C) above the 20th century average.
- This was the highest among all 136 years in the 1880–2015 record, surpassing the previous record set last year by 0.29°F (0.16°C) and marking the fourth time a global temperature record has been set this century.
- This is also the largest margin by which the annual global temperature record has been broken.
- Ten months had record high temperatures for their respective months during the year.
- The five highest monthly departures from average for any month on record all occurred during 2015.
However what matters more is not the temperature for one year (as they get affected by many variables). In the last 40 years or so the average temperature (sea and land) has risen around 0.7 degrees. The graph above shows the average by decade.