Last year was the hottest on record, analyses by two major US agencies. Both Nasa and the National Oceanic and Atmospheric Administration said the global average temperature in 2014 was more than 1.2 degrees Fahrenheit above normal.

Scientists said the record temperatures were spread around the globe, including most of Europe stretching into northern Africa, the western United States, far eastern Russia into western Alaska, parts of interior South America, parts of eastern and western coastal Australia and elsewhere.

With the exception of 1998, 10 of the warmest years on record have occurred since 2000.

Since 1880, when record-keeping began, Earth's average surface temperature has warmed by about 1.4 degrees Fahrenheit (0.8 degrees Celsius), a trend that is largely driven by the increase in carbon dioxide and other human emissions into the planet's atmosphere, Nasa said.

The global heat streak of the 21st century results in some mind-boggling statistics.

First, the NOAA calculates global average temperature going back to 1880. That's 135 years. So if no other forces were in play and temperatures last year were totally at random, then the odds of 2014 being the warmest on record are 1 in 135. Not too high.

But record and near record heat keep happening. The three hottest years on record – 2014, 2010 and 2005 – have occurred in the last 10 years. The odds of that happening randomly are 3,341 to one, calculated John Grego of the University of South Carolina.

Nine of the 10 hottest years on record have occurred in the 21st century. The odds of that being random are 650 million to one, statisticians said.

Thirteen of the 15 the hottest years on record have occurred in the last 15 years. The odds of that being random are more than 41 trillion to one.

All 15 years from 2000 on have been among the top 20 warmest years on record. The odds of that are 1.5 quadrillion to one. A quadrillion is a million billion.

And then there's the fact that the last 358 months in a row have been warmer than the 20th-century average, according to NOAA. The odds of that being random are incredibly high – a number with more than 100 zeroes behind it, Grego said.