The effect of these greenhouse gases is that the planet has gotten hotter. Since the dawn of the Industrial Age, the average global temperature has risen one degree Celsius; some areas have even experienced a rise of over two degrees. That may not sound like much, but, on a global scale, it is. And there are many far-reaching consequences.
In practice, most people find that recommender systems do an OK job of finding things that are OK, but that they rarely help us discover things we truly love.