Every area of the globe has warmed since instrument records began in 1880, NASA data shows. The planet isn't warming equally, however — the fastest temperature increases are taking place at the poles. The Arctic, for example, is warming at more than twice the rate of the rest of the globe, melting sea ice, glaciers and permafrost.
The bottom line: Due largely to human emissions of greenhouse gases, there is virtually no such thing as a cooler than average year on Earth anymore. (The last cooler-than-average month was 30 years ago, in December 1984).
"The globe is warming. There’s noise in each month or year but by the time you are looking at decadal means that part is small and the trends undeniable," said Gavin Schmidt, the director of NASA's Goddard Institute for Space Studies.
What to watch: This year is expected to be among the top five warmest years.
How to read this map: It shows how much global temperatures have varied from the 1951-1980 average for each decade since 1880. NASA uses the 1951-80 period as a temperature baseline, or reference period.