Scientists first noticed the dangerous effects of carbon dioxide emissions back in 1896; the press started reporting on rising temperatures in 1930. And yet, more than 80 years later, the nations of the world still haven't passed sufficient legislature to curtail the disastrous effects humans have on the planet.

Recent studies show that the next 15 years of climate-related decisions, says Felipe Calderón, the former president of Mexico, will "determine the future of the world." The message is clear: If we don’t implement the difficult but necessary changes to reduce the effects of climate change, it will be all but impossible to turn back.

Because climate change is on everyone's lips and top of mind during UN Week, we created the timeline below to provide some background on climate change and the policies and movements that have attempted to keep it in check. From first recognized Earth Day and rising carbon dioxide levels to legislation like the Montreal Protocol, a flip through the timeline below will help you wrap your head around the importance of this week's summit — and its impact on the future of our planet.

Andrew Freedman and Lauren Drell contributed to the reporting of this piece