The predecessors of Pope Francis had concerns about the ecology too.
Pope Benedict had much to say - but never dedicated an encyclical to the issue - he left that up to his successor. Pope Francis' encyclical hasn't even been released yet - nor has it been leaked, as far as I know. But some Catholics are already attacking the Holy Father, going so far as to dismiss the Holy Father as "an ideologue and a meddlesome egoist." Wow!
What would Benedict say?
In fact, what did he say?
Peace“If you want to cultivate peace, protect creation.” — Message for World Day of Peace, (par. 14), 2010.
'fruit of the earth,' 'fruit of the vine,' and 'work of human hands.'
"The Eucharistic form of life can thus help foster a real change in the way we approach history and the world. The liturgy itself teaches us this, when, during the presentation of the gifts, the priest raises to God a prayer of blessing and petition over the bread and wine, 'fruit of the earth,' 'fruit of the vine,' and 'work of human hands.' With these words, the rite not only includes in our offering to God all human efforts and activity, but also leads us to see the world as God's creation, which brings forth everything we need for our sustenance. The world is not something indifferent, raw material to be utilized simply as we see fit. Rather, it is part of God's good plan, in which all of us are called to be sons and daughters in the one Son of God, Jesus Christ (cf.Eph 1:4-12)." — Sacramentum Caritatis (par. 92), 2007.
Linking ecology and human life
"Our duties towards the environment are linked to our duties towards the human person, considered in himself and in relation to others. It would be wrong to uphold one set of duties while trampling on the other. Herein lies a grave contradiction in our mentality and practice today: one which demeans the person, disrupts the environment, and damages society." — Caritas in Veritate, (par. 51).
“The deterioration of nature is in fact closely connected to the culture that shapes human coexistence: when ‘human ecology’ is respected within society, environmental ecology also benefits." — Caritas in Veritate, (par. 51; emphasis in original).
Catholics have to have confidence that the Holy Father (Pope Francis) will not step beyond Catholic doctrine and teaching in the new encyclical.
Again, from Pope Benedict XVI:
Confronting relativism“Yet freedom cannot be absolute, since man is not himself God, but the image of God, God’s creation. For man, the path to be taken cannot be determined by caprice or willfulness, but must rather correspond to the structure willed by the Creator.” — New Year’s Address to the Diplomatic Corps, January 11, 2010.
Read everything in context here.