Two things.
First, climate change is real. Geologists (not leftist ones) have climate records that go back hundreds of thousands of years. The climate is definitely warming up past normal variation, and that is highly likely to be very bad for the entire planet. Also, humans are the definitely the cause of this change, because the other major climate changes in the past were all caused by an abnormal/outside factor (a massive, multi-thousand-year volcanic eruption or a meteor hitting Earth). So we should be more careful.
Second, while practicing some environmental awareness is likely a good thing, I do not think it qualifies as sinful. It is negligence or thoughtlessness, at most. Additionally, I do believe that it should be taken too far or it will cross into idolatry (earth worship). Be careful there, too.
Thirdly, while recycling and such is good for the environment, the best thing is to just use less stuff. Don’t eat out all the time, get local food products, be thrifty with what you do buy. Basically, just be conscientious about what you are getting. We don’t need a lot of what we buy, so buy less. This can also tie into rejecting materialism.
Finally, I swear by the Bible that I am not a liar or even particularly leftist. In fact, I take most of my political cues from the Catechism, with a tendency towards the conservative side.
