Different colours are used to illustrate the passage of time. The spiral begins with purple for early years, then changes to blue, green and finally to yellow for the most recent years.
The animation clearly shows that warming has accelerated in recent years. If this continues, it won't be long before average temperatures on Earth will be 1.5 degrees Celsius higher than they were in pre-industrial times.
It is unclear what will happen if temperatures continue to climb. At 2°C, scientists say sea levels will likely rise rapidly and extreme heat could kill off the crops we depend on for food.
NASA has its own animation (30 seconds) showing the warming trend from 1880-2015. It is even scarier.