Globally, 2012 was one of the warmest years on record, according to separate reports from NOAA and NASA.
NOAA's 2012 State of the Climate report, released Tuesday, concluded that last year was the 10th warmest since record keeping began in 1880.
According to NOAA, 2012 marked the 36th consecutive year with global average temperatures above last century's average. Every year of the 21st century thus far has been one of the top 14 warmest years in 133 years of recordkeeping.
James E. Hansen, the director of NASA's Goddard Institute for Space Studies in New York, said during a Tuesday press call, "Each decade has been significantly warmer than the prior decade since the mid-1970s." He added, "We can predict with confidence that the next decade will be warmer than the last."
NOAA confirmed last week that 2012 was the warmest year on record for the contiguous U.S., based on records dating back to 1895. The year was one degree Fahrenheit warmer than the previous record holder, 1998. According to Climate Central, Jake Crouch, a climate scientist at NOAA's National Climatic Data Center in Asheville, N.C., said, "Climate change has had a role in this [record]."
Using NOAA's U.S. Climate Extremes Index, 2012 also ranked as the second-most extreme year on record. The U.S. saw Hurricane Sandy, a record-breaking wildfire season and an ongoing and severe drought which continues to plague large swathes of the Midwest.
A draft of the U.S.' third National Climate Assessment was released last week, reinforcing, among other things, that Earth's climate is quickly changing as a result of human activities. The Huffington Post's Tom Zeller Jr. reported, "Observed weather extremes are on the rise, and the possible connection between at least some of these events and human-induced climate change is also more strongly supported by the science."
NASA's analysis of 2012 temperatures found the year to be the ninth warmest on record.
From NASA: NASA's analysis of Earth's surface temperature found that 2012 ranked as the ninth-warmest year since 1880. NASA scientists at the Goddard Institute for Space Studies (GISS) compare the average global temperature each year to the average from 1951 to 1980.
Thomas Karl, the director of NOAA's National Climatic Data Center said during the Tuesday call that there are "minor differences" between NOAA and NASA's data sets. Yet these independent analyses confirm that global temperature anomalies are occurring more frequently.
NASA explains, "Consistency between the two analyses, together with those produced by other countries, increases confidence in their accuracy."
Atmospheric carbon dioxide concentrations were at about 285 parts per million (ppm) in 1880, NASA noted, and rose to around 315 ppm by 1960. Today, the concentration is above 390 ppm.
Karl said that increasing atmospheric greenhouse gases are the primary reason "We are seeing an increase in the rate of temperature warming."
Increased global temperatures have also meant increased melting of Arctic sea ice. Karl said the decrease in Arctic sea ice area is "remarkable."
Lou Leonard, Managing Director of Climate Change for the World Wildlife Fund, said in a statement, "It should be seen as a dire warning that we are destroying one of our most important natural places and threatening the rest of the planet in the process."