It is hard to think that the skeptics of global warming would aim for a low-carbon lifestyle.
One is free to think and say what one wants, but that doesn't mean that one can do anything.
ご質問ありがとうございます。
"It is hard to think that"＝「～は考えにくい」
"the skeptics of global warming"＝「温暖化の懐疑論者が」
"would aim for a low-carbon lifestyle."＝「脱炭素化の生活を心掛けるとは。」
"One is free to think and say what one wants"＝「思想や行動は自由だ」
"but that doesn't mean that one can do anything."＝「しかし、それは何をやっても良いということではない。」
ご参考に。
The problem is that it is hard to think that climate change skeptics care about reducing carbon emissions
The problem is that~
問題は
it is hard to think that~
とは考えにくい事だ
climate change skeptics care about reducing carbon emissions
温暖化懐疑論者が脱炭素を心がける
「脱炭素を心がける」をreducing carbon emissionsにしましたが、普段の生活の温暖化にの影響について話すときにreducing one's carbon footprint (直訳：自分の炭素足跡を小さくする）という表現がよく使われていますので、この場合でも使っていいですね。
ご参考になれば幸いです。
アメリカ合衆国 
