What is consumerism and what does the Pope see wrong with it?

In the most recent encyclical Laudato si' , Pope Francis condemns consumerism. What does he mean by the word consumerism? And what does he see wrong with it? > To blame population growth instead of extreme and selective consumerism on the part of some, is one way of refusing to face the issues When someone consumes something, it means that the consumer enjoys and benefits from it. Why is it wrong?