Others have noted the gruesome video posted by the British wing of the environmental group 10:10. I won't link to it here, because it really is disgusting; but here's a good summary of the controversy. In short, it's a series of scenes in which a teacher, a boss, a football team, and so on "suggest" that people reduce their carbon emissions by 10%. They ask who is on board, and who isn't. "No pressure." Then they push a little red button and those not on board explode, covering everyone else, and the camera lens, with blood and guts.
Now, environmental stewardship is one of the important features of Catholic morality: we are here to keep and tend the garden, after all. But ads like this betray a bizarre and anti-human attitude among some environmental activists. It's vital to realize that humanity is itself part of the environment, and the part for which we have the greatest responsibility to protect and respect.
In other words, environmental protection only makes sense as a life issue, and when you throw out the connection to human dignity you end up in the culture of death.
Other Catholic responses: