Carl Sagan is one of my heroes. Undoubtedly, he is one of the best science communicators who has ever walked our beautiful Pale Blue Dot.

In this video, he holds a speech on climate change at the Emerging Issues Forum at Cornell University in 1990.

As always, his rhetoric eloquence is striking and makes listening to him a pure joy. However, listening to his speech also brought a deep sadness over me. Here, Sagan explains why global warming is bad, why we need to take it seriously and what we can do to mitigate the risks.

It made me sad because Sagan mentions 32 years ago the same exact issues and reasons that we know of today. Humanity knew decades ago, but only recently did we start doing something about it. This will not come as news to most of you, but it’s still important to face this reality over and over again.

I recommend that you take an hour of your day and listen to Dr Sagan. He will tell you nothing new, but the way he will tell you will make you feel excited, hopefully, sad, and angry.