A Major Milestone: 1°C

The planet reached two important climate milestones this year. The globally averaged concentration of CO2 reached 400 parts per million, and the global average temperature climbed to more than 1°C (1.8°F) above pre-industrial levels for the first time since recordkeeping began.

The latter is a milestone noted by the U.K. Met Office and is halfway to the 2°C threshold widely discussed at the Paris Climate Conference. Most of this warming has occurred since the 1950s, and if our current rate of greenhouse gas emissions continues, it will likely take less time to climb from 1°C to 2°C than from 0°C to 1°C.

NOAA uses a slightly different baseline when reporting the global average temperature change. Through the first 10 months of this year, the temperature of combined land and ocean surfaces is 0.86°C (1.55°F) above the 20th century average. And just like the U.K. Met Office, the NOAA data indicate that the warming shows no sign of changing direction.