It’s official — 2014 is the hottest year on record. The global ocean temperature was also the highest on record while many land areas were also warmer than normal or set records such as many countries in Europe and the western U.S. The only major blue spot for 2014 was the eastern half of the U.S.

Since the advent of modern recordkeeping in 1880, the global average temperature has risen 1.6°F. The trend is one of the hallmarks of global warming and tightly tied with the rise in human CO2 emissions. Warming has accelerated since the first Earth Day in 1970. The global average temperature has risen by about 0.3°F per decade since then.

The average global temperature fluctuates every year. However, when you look at a snapshot of the global temperature trend, it's on the rise - particularly since 1970. The main cause? Carbon dioxide and other greenhouse gas emissions from human activities. There are plenty of factors that influence temperatures in different regions across the