La Niña is a part of the El Niño southern oscillation, a climate fluctuation that slowly sloshes vast bodies of water and heat between different ocean basins and disrupts weather patterns around the world.

The past two years have seen month after month become the planet's hottest recorded. Climate scientists say human-produced greenhouse gases account for the majority of the warming.

For Americans, news of a record warm January might seem odd given how cold it was. But the U.S. is just a tiny fraction of the planet's surface, and "a much larger area of the planet’s surface was much, much warmer than average,” Burgess said.

Despite an emerging La Nina bringing cooler conditions to the tropical Pacific, last month has been deemed the warmest January on record.