Was 2014 really the hottest year on record?

Is climate change real, has the Earth got warmer, and was 2014 truly the hottest year on record? NASA waded into the heated argument over heat with unequivocal claims that we can't ignore rising temperatures, citing not only its own numbers but those of the National Oceanic and Atmospheric Administration (NOAA) and concluding the environment is getting hammered by greenhouse gases like carbon dioxide. However, while the claims may be bold, other researchers are less convinced that the results are so clean-cut, arguing that the sheer complexity of taking an average of the world's temperature leaves certainties far from reach.

According to NASA and NOAA, nine of the ten warmest years since figures were recorded have been since the year 2000, only 1998 spoiling the clean sweep.

More worryingly, according to the two agencies, 2014 was "the warmest year on record" and there has been an continuing acceleration of temperature rises. Although average temperatures have gone up by around 1.4 degrees Fahrenheit (or around 0.8 degrees Celsius) since 1880, numbers crunched by the Goddard Institute of Space Studies (GISS) in New York suggests it's within the past thirty years that the major damage has been done.

Scientists from both teams are under no illusions about what is causing the change, blaming emissions of carbon dioxide and other gases for the gradual increase.

"This is the latest in a series of warm years, in a series of warm decades. While the ranking of individual years can be affected by chaotic weather patterns, the long-term trends are attributable to drivers of climate change that right now are dominated by human emissions of greenhouse gases" Gavin Schmidt, Director, GISS

However, their certainty isn't shared throughout the climate change community. According to parallel research by Berkeley Earth, the situation is simply too complex – and the differences in the numbers too small – to draw such clean-cut conclusions.

"The global surface temperature average (land and sea) for 2014 was nominally the warmest since the global instrumental record began in 1850," the California team concurs, but goes on to caution that "however, within the margin of effort, it is tied with 2005 and 2010 and so we can't be certain it set a new record."

As Berkeley Earth flags, warmth is not ubiquitously raised across the planet. For instance, Michigan experienced its 14th coldest year, it's pointed out.

The final conclusion from Berkeley is that, while the highest temperature year can't necessarily be figured out, the Earth's average temperature for the last decade is still high and has been consistently so for the past decade.

It's not the first time NASA has issued ominous warnings about climate change, insisting last year that it was probably too late to reverse melting glaciers. Still, even with the numbers collected from tens of thousands of stations around the globe, arguments over whether temperature changes are man-made or natural continue to rage, and differences in opinion among researchers are unlikely to settle them any time soon.

VIA NASA; Berkeley Earth