From The New York Times:
Even as much of the United States shivered under frigid conditions last month, the planet as a whole had its warmest January on record, scientists said on Thursday.
The warmth came as something of a surprise to climate researchers. It occurred during La Niña conditions in the Pacific Ocean, which tend to lower the globe’s average temperature, at least temporarily. Earth’s surface has now been so warm for so much of the past two years that scientists are examining whether something else in the planet’s chemistry might have changed, something that is boosting temperatures beyond what carbon emissions alone can explain.