And, indeed, if one reads the Core Values presented on the Green Party website that appears a quite justified claim (though, if a claim of affinity to Catholic social teaching is being made, one might want to differ with the equivalence of "other species" to the human species indicated at point 5). However, if one digs more deeply, Green Party policy is in favour of legal access to abortion and of a legalisation of assisted euthanasia which has provisions somewhat akin to those of the original 1967 Abortion Act (see points HE 516/517 and HE526 at this page on their website - both of which are preceded by points that make for an attractive rhetoric which is then in a certain opposition to the concrete proposals).
And in the last 24 hours, the Green Party launched their LGBTIQ Manifesto for the 2015 General Election. The coverage at the ITV news website includes a video clip which suggests that there was little interest in the launch itself. However, a Q+A with Pink News readers opened up a more significant aspect of future Green Party thinking on LGBTIQ issues. The manifesto itself is reported here; but Natalie Bennett's "openness" to polyamorous marriages is reported here:
We have led the way on many issues related to the liberalisation of legal status in adult consenting relationships, and we are open to further conversation and consultation.”That this represents a significant misappropriation of the idea of "the common good" as articulated by Catholic social teaching can be readily be seen by referring to Pope Francis' recent General Audience addresses on male-female complementarity and marriage: 15th April 2015, 22nd April 2015 (with implications for the relative standing of the human person vis a vis other creatures), 29th April 2015 (the first audience on marriage, with at least one more to follow that will in due course be linked from this page). It is also worth recalling the almost unprecedented manner of Pope Francis' endorsement of Pope Paul VI's encyclical Humanae Vitae during his visit to the Far East in Autumn 2014.
I think we should not be under any illusions about what we should expect in Pope Francis forthcoming encyclical on environmental matters, or in the engagement of the Holy See as far as Sustainable Development Goals at the United Nations are concerned. The markers are clear in Pope Francis' public statements. The endorsement of a principle that action in favour of environmental sustainability is a moral imperative (and some application of that principle to particular situations) is not going to embrace the "progressive" agenda of such as the UK Green Party, though it may have some comparability of language.
Just as the Green Party use of "the common good" as a campaign strapline is a significant misappropriation of a principle of Catholic social teaching, so will any attempt to represent Pope Francis' encyclical as support for their position also be a gross misrepresentation of that encyclical.