Despite the “polar vortex” that made news across much of the United States in 2014, last year was the warmest on Earth since record-keeping began in 1880, according to two reports released Friday.
The globe's average temperature of about 58 degrees was 1.24 degrees above the 20th century average in 2014, according to the National Oceanic and Atmospheric Administration. NASA meanwhile calculated the average to be 1.22 degrees above-average, using similar data but different methods.
The scientists said the trend is “largely driven by the increase in carbon dioxide and other human emissions into the planet’s atmosphere.”
The estimates broke a record set in 2010, and in 2005 before that. Nine of the 10 warmest years on record have now occurred since 2000, according to NASA. And it was the 38th year in a row that the world was warmer than the 20th century average, according to NOAA data, meaning that most people in the United States have never experienced a cooler-than-normal year.
“The globe is warmer now than it has been in the last 100 years and more likely in at least 5,000 years,” said climate scientist Jennifer Francis of Rutgers University, who wasn't part of either research team. “Any wisps of doubt that human activities are at fault are now gone with the wind.”
Temperature anomalies were record-shattering in the world’s oceans, which will have lingering effects this year and beyond, the scientists said. Water is slower to change temperature than air and land and its warmth can have larger climate effects.
“Even if conditions were to change this year with a significant event, like a volcano or something, it will take a while for the oceans to cool down,” Thomas Karl, director of NOAA's National Climatic Data Center, said on a conference call with reporters. “That gives some added energy for 2015.”
Climate scientists say another significant takeaway from 2014's record is that it happened during a year where there was no El Nino weather oscillation. During an El Nino, when a specific area of the central Pacific warms unusually and influences weather worldwide, global temperatures tend to spike. Previous records, especially in 1998, happened during El Nino years.
Of course, there were some relatively cool pockets around the globe -- the eastern half of North America, in particular. In Maryland, 2014 was the 47th-coldest on record, while it was Baltimore's 13th-coldest year. The year was among the coldest on record for states around the Great Lakes and down the Mississippi River Valley.
But the scientists said the chill of last winter's polar vortex and a jet stream pattern bringing cooler-than-normal temperatures to much of the United States through the summer is not all that uncommon. And it was counterbalanced by record warmth across far eastern Russia, the western part of the United States, interior South America, much of Europe, northern Africa and parts of Australia, Karl said.
A New York-based unit of NASA's Goddard Space Flight Center in Greenbelt gathered its data using a network of 6,300 weather stations and ocean measurements taken from ships and buoys. After taking into account differences in spacing between weather stations and the effects of urban heat islands that could skew readings, an average temperature was calculated and compared to a baseline period of 1951 to 1980.
NOAA scientists used much of the same raw data but compared it to a different baseline period and used different methods to calculate the average.
The Associated Press contributed to this report.