It is pretty simple, really. Our mother’s womb nourished us, and provided us a place to develop. Likewise, the planet earth, through God’s creation, provides us food, water, and a place to live. It does the same for all of God’s creatures.
As stewards of all of God’s creation (Gen 1:26), we are called to maintain it thoughtfully, and in ways that will provide for generations to come. In other words, exercise a conservative philosophy regarding ecology, as well as resource exploitation and allocation.
Several previous Popes, including St. John Paul II, spoke against unrestrained capitalism (as well as socialism), which doesn’t include concern for others, but for profit only. Pope Francis continues this discussion, reiterating the need to think about and treat all people with the dignity God has given them.
Regarding financial speculation, I have no idea what he is talking about. Speculation is a way to provide future market stability, as well as accurate forecasting; think airlines purchasing fuel futures.
One last thing, since he was speaking to a group working on agricultural issues, it does make sense that he put emphasis not just on people, but also on land use and the environment in general. This was not an address in a vacuum, nor was it specifically a papal pronouncement on environmental issues in general.
So Christians call it 'mother' and really mean it? I don't think that is a Christian idea. Sorry. As for the Pope's statement on anything economic, lefties need not apply. The US is suffering under them now, they have no economic ideas worth anything, for them it is about power.