2013 was the fourth, sixth or seventh hottest year on record, say scientists

2013 was one of the hottest years on record.

But just how hot was it, and how does it compare to other years? Organizations that monitor global temperatures disagree.

According to a report published by World Meteorological Organization (WMO) today, a specialized agency of the United Nations, 2013 tied with 2007 as the sixth warmest on record.

But a recent report by NASA earlier this year ranked 2013 (tied with 2009 and 2006) as the seventh warmest year since 1880.

The discrepancies do not end here. In a global analysis, the National Oceanic and Atmospheric Administration (NOAA) ranked 2013 (along with 2003) as the fourth warmest year globally since records began in 1880.

The difference in rankings can be mindboggling, but apparently, the differences in temperature recordings is tiny, say experts.

"The difference between the joint fourth place and the joint seventh place is within 0.02 C of a degree," Gavin Schmidt, deputy director of NASA's Goddard Institute for Space Studies told CBCnews in January. He also added that NASA and NOAA process their data differently.

"Different data and averaging methods lead to slightly different global temperature estimates that can lead to small switches in the ranking of years," Harvard University climate expert Peter Huybers told the Monitor. 

But "the key point here is that, no matter how you slice it, 2013 was among the top 10 warmest years, as have been most recent years," Michael Mann, a climatologist at Penn State University told Climate Central.

“Naturally occurring phenomena such as volcanic eruptions or El Niño and La Niña events have always contributed to frame our climate, influenced temperatures or caused disasters like droughts and floods," said WMO Secretary-General Michel Jarraud in a press release.

2013 saw two major cyclones – Super Typhoon Haiyan, known as Yolanda in the Philippines and cyclone Phailin in India. In addition to extreme weather conditions, Mr. Jarraud points to danger posed by "human-induced climate change."

"We saw heavier precipitation, more intense heat, and more damage from storm surges and coastal flooding as a result of sea level rise – as Typhoon Haiyan so tragically demonstrated in the Philippines," he said.

All these factors caused temperatures to in 2013 endangering those in vulnerable areas.

“Comparing climate model simulations with and without human factors shows that the record hot Australian summer of 2012/13 was about five times as likely as a result of human-induced influence on climate and that the record hot calendar year of 2013 would have been virtually impossible without human contributions of heat-trapping gases, illustrating that some extreme events are becoming much more likely due to climate change,” the study concluded.