Atmospheric scientists from two major US agencies and one UK agency have declared 2016 as the hottest year on record, surpassing the ones made in 2015 and 2014, 

According to The Guardian, scientists from NASA's Goddard Institute for Space Studies, the National Oceanic and Atmospheric Administration (NOAA) and the UK Met Office showed very similar results when it comes to the record rise of world temperatures last year. NOAA reported that average surface temperatures in 2016 were 0.07 degrees Fahrenheit higher than 2015.

Moreover, NOAA said global temperatures in the first 8 months of the year (January - August 2016) were the highest in their records since the 1880s, reported  The Washington Post.

So how did the scientists, particularly NASA, estimate that 2016 was the hottest year to date?

NASA's data came from three specific sources:  6,300 weather stations; Antarctic research stations; and buoys and ships that measure surface temperature. On the other hand, NOAA also uses similar data but analyzes it differently and independently, particularly Arctic temperature change.

The researcher's data indicates also that despite differences in the rise of both land and sea temperatures (land temperatures were going up faster than sea temperatures), it is the Arctic area which has recorded a temperature change of at least 2 to 3 times higher than the global mean temperature rise.

To determine the cause of the rising temperatures and climate changes, the researchers studied satellite records of different parts of the Earth's atmosphere, as well as releasing balloons up in the air as part of radiosonde data. With these methods, they found out that temperatures 12,000 meters up have increased compared to previous years but temperatures at ground level were cooling, they inferred, to the increase in carbon dioxide gases, and ozone depletion.

Thereby, scientists concluded that the main cause for warming temperatures are manmade greenhouse gases, and not external factors such as heat changes from the sun.