To judge from some of the headlines, you would have thought he claimed that extirpating homosexuality was as urgent as protecting the rainforest. His actual words were much more rambling and even progressive: that "[the earth] is not simply our property to be exploited according to our interests and desires" and the same is true of our gendered nature. This is why
he attacked "gender studies" in particular, because they seem to make human sexuality something infinitely malleable and subject to our will.
He sees human nature, and the nature all around us both as gifts of God, with their own intrinsic values independent of our purposes. Self-fulfilment, in this view, is not doing what we want, but what God – or our true nature – wants. The real target of his attack is not the condition of homosexuality, but the more general attitude which says that sex is solely a matter of pleasure between autonomous individuals.
You may disagree with him. But given the consistent Catholic view that a stable, heterosexual family is the foundation of society and the place where all morals and virtues are best nurtured, his remarks are not egregious bigotry. Without – he would argue – families in which children may grow up with a sense of responsibility for others, and for the earth, there will be no effective action to save the planet.
The Catholic church is a conservative organisation. It believes that homosexuality is unnatural in the sense that it is not what God had in mind. That isn't going to change in a hurry. But it is not homophobic in the way that evangelical protestantism can be. I really don't think that its official line on gays suggests that they are greater sinners, or a greater threat to marriage, than adulterers. The defence of the family is not always in Roman Catholic usage a code for scapegoating gay people.