Warning of the problem, recognizing the problem, putting real measures in place to correct the problem is exactly what LA did to reduce smog [1]. In 1952, London had a smog event so bad that it literally killed 12,000 people [2]. That is pretty alarming, and the UK enacted clean air laws. Meanwhile, in 2013 over a third of all deaths in and around Bejing were linked to pollution (unbreathable air due to smog). Alarmists warned of the destruction of the ozone layer, but where are they now? Nowhere, because significant action was taken, and the damage was reversed. Panic over acid rain? Cap and trade restrictions on SO2 and NOx in the US and EU reduced acid rain causing emissions faster and cheaper than predicted [3]. In every single case, big business fought and complained and were forced to comply.
Being alarmist about real issues is like being a fire alarm for a real fire.
[1] https://www.aqmd.gov/home/research/publications/50-years-of-...
[2] https://en.wikipedia.org/wiki/Great_Smog_of_London
[3] https://en.wikipedia.org/wiki/Acid_rain