NOAA, NASA: 2015 was Earth's hottest by a wide margin

NOAA said 2015's temperature was 58.62 degrees Fahrenheit (14.79 degrees Celsius), passing 2014 by a record margin of 0.29 degrees.

NASA, which measures differently, said 2015 was 0.23 degrees warmer than the record set in 2014 and 1.6 degrees above 20th century average.

Because of the wide margin over 2014, NASA calculated that 2015 was a record with 94 percent certainty, more than double the certainty it had last year when announcing 2014 as a record.

Because of the pace of rising temperatures, "we don't have very far to go to reach 1.5," Karl said.

[...] 1.5 or 2 degrees are not "magic numbers" and "we're already seeing the impacts of global warming," said NASA Goddard Institute of Space Studies director Gavin Schmidt.

Non-scientists who reject mainstream climate science often criticize NOAA for adjustments to past temperature records to reconcile the measurement devices with modern techniques, but even without any adjustments NOAA data shows 2015 as the hottest year on record, Karl said.