1. There is no halachic issue. If you accept their theory about carbon emissions causing devastating global warming that will put everyone’s life in danger, we would have no halachic objections to their demands. If as they believe with a religious fervor, that the world is ending, halacha would support measures to prevent it. It is their underlying theory that is questionable.
2. We have a longer perspective on history; our “memories” go back millenia, whereas most Americans go back decades, at most. Based on accounts of what crops grew where, it is clear that it was warmer in the past than it is today, particularly during the period of Bayis Sheini (the “classical period”) and the period of the Rishonim (the “high Middle Ages”). The goyim seem to be confusing routine climate and weather variations with a disastrous change in climate. When the environmentalists claim that their “science” asserts that there has been horrific warming since the late 18th century, they are choosing one of the coldest periods in human history as their “base”. They also ignore that the historic cold periods led to mass famines and migration of climate refugees is large numbers, often leading to acts of genocide, whereas the warm periods in the past were actually quite pleasant leading to higher food production and a flowering of civilizations. Note that even today, those with money go to Florida for the winter, rather than Alberta or Montana for the summer.
3. There is a halachic dimension to be considered, in that the secular environmentalists seem prone to perceive whatever data they encounter as “proving” a pending “apocalypse” (note their similar response to Covid19), and this penchant for seeing a disaster behind every every data set is probably based on the Christian “bible”, leading to the idea that perhaps it is Avodah Zarah for Yidden to take such “apocalyptic” thinking seriously. We have been around a very long term, and by now we should trust Ha-Shem not to shmush us.